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ART001882829
|
oai_dc
|
Integration of in-situ load experiments and numerical modeling in a long-term bridge monitoring system on a newly-constructed widened section of freeway in Taiwan
|
Integration of in-situ load experiments and numerical modeling in a long-term bridge monitoring system on a newly-constructed widened section of freeway in Taiwan
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Yi-Tsung Chiu(National Taipei University of Technology); Tzu-Kang Lin(National Chiao Tung University); Hsiao-Hui Hung(National Center Research on Earthquake Engineering); Kuo-Chun Chang(National Taiwan University); Yu-Chi Sung(National Taipei University of Technology)"
] |
The widening project on Freeway No.1 in Taiwan has a total length of roughly 14 kilometers,and includes three special bridges, namely a 216 m long-span bridge crossing the original freeway, an F-bentdouble decked bridge in a co-constructed section, and a steel and prestressed concrete composite bridge.
This study employed in-situ monitoring in conjunction with numerical modeling to establish a real-timemonitoring system for the three bridges. In order to determine the initial static and dynamic behavior of thereal bridges, forced vibration experiments, in-situ static load experiments, and dynamic load experimentswere first carried out on the newly-constructed bridges before they went into use. Structural models of thebridges were then established using the finite element method, and in-situ vehicle load weight, arrangement,and speed were taken into consideration when performing comparisons employing data obtained fromexperimental measurements. The results showed consistency between the analytical simulations andexperimental data. After determining a bridge's initial state, the proposed in-situ monitoring system, which isemployed in conjunction with the established finite element model, can be utilized to assess the safety of abridge's members, providing useful reference information to bridge management agencies.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001882805
|
oai_dc
|
Vision-based remote 6-DOF structural displacement monitoring system using a unique marker
|
Vision-based remote 6-DOF structural displacement monitoring system using a unique marker
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"전해민(한국과학기술원); Youngjae Kim(KAIST); 이동화(한국과학기술원); 명현(한국과학기술원)"
] |
Structural displacement is and important indicator for assessing structural safety. For structural displacement monitoring, vision-based displacement measurement systems have been widely developed; however, most systems estimate only 1 or 2-DOF translational displacement. To monitor the 6-DOF structural displacement with high accuracy, a vision-based dispalcement measurement system with a uniquely desinged marker is proposed in this paper. The system is composed of a uniquely disigned marker and a camera with a zooming capability, and relative translational and rotational displacement between the marker and the camera is estimated by finding a homography transformation. The novel marker is designed to make the system robust to measurement noise based on a sensitivity analysis of the conventional marker and it has been verified through Monte Carlo simulation results. The performance of the displacement estimation has been verified through two kinds of experimental tests; using a shaking table and a motorized stage. The results show that the system estimates the structural 6-DOF displacement, especially the translational displacement in Z-axis, with high accuracy in real time and is robust to measurement noise.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001882810
|
oai_dc
|
Crack location in beams by data fusion of fractal dimension features of laser-measured operating deflection shapes
|
Crack location in beams by data fusion of fractal dimension features of laser-measured operating deflection shapes
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"R.B. Bai(Hohai University); X.G. Song(Newcastle University); M. Radzieński(Polish Academy of Sciences); W. Ostachowicz(Warsaw University of Technology); S.S. Wang(Hohai University); M.S. Cao(Hohai University)"
] |
The objective of this study is to develop a reliable method for locating cracks in a beam usingdata fusion of fractal dimension features of operating deflection shapes. The Katz’s fractal dimension curveof an operating deflection shape is used as a basic feature of damage. Like most available damage features,the Katz’s fractal dimension curve has a notable limitation in characterizing damage: it is unresponsive todamage near the nodes of structural deformation responses, e.g., operating deflection shapes. To address thislimitation, data fusion of Katz’s fractal dimension curves of various operating deflection shapes is used tocreate a sophisticated fractal damage feature, the ‘overall Katz’s fractal dimension curve’. This overallKatz’s fractal dimension curve has the distinctive capability of overcoming the nodal effect of operatingdeflection shapes so that it maximizes responsiveness to damage and reliability of damage localization. Themethod is applied to the detection of damage in numerical and experimental cases of cantilever beams withsingle/multiple cracks, with high-resolution operating deflection shapes acquired by a scanning laservibrometer. Results show that the overall Katz’s fractal dimension curve can locate single/multiple cracks inbeams with significantly improved accuracy and reliability in comparison to the existing method. Datafusion of fractal dimension features of operating deflection shapes provides a viable strategy for identifyingdamage in beam-type structures, with robustness against node effects.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001882809
|
oai_dc
|
Hand arm vibration measurement using micro-accelerometer in different brick structures
|
Hand arm vibration measurement using micro-accelerometer in different brick structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"K. Gomathi(Kongu Engineering College); A. Senthikumar(Dr.MCET); S. Shankar(Kongu Engineering College); S. Thangavel(Kongu Engineering College); R. Mohana priya(Dr.MCET)"
] |
Hand-Arm Vibration Syndrome (HAVS) is a group of diseases caused by exposure of the hands to vibration while operating the hand held power tools such as road breaker, drilling machine, demolition hammer in construction works. In this paper, area-changed capacitive micro-accelerometer is designed to measure the vibration exposure on worker's hand when operating a drilling machine on various blocks such as clay block, paver block and solid cement block. The design process includes mathematical modelling of micro-accelerometer and simulations are done using INTELLISUTTE 8.6. Experimental results are taken for various blocks surfaces using conventional and micro-accelerometer. Comparisons show that usage of are-changed micro-accelerometer for Hand-arm vibration monitoring provides better sensitivity, which in turn reduces the risk of HAVS in workers.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001882807
|
oai_dc
|
Fatigue performance monitoring of full-scale PPC beams by using the FBG sensors
|
Fatigue performance monitoring of full-scale PPC beams by using the FBG sensors
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Licheng Wang(Dalian University of Technology); Jigang Han(Liaoning Provincial Design Institute); Yupu Song(Dalian University of Technology)"
] |
When subjected to fatigue loading, the main failure mode of partially prestressed concrete (PPC)structure is the fatigue fracture of tensile reinforcement. Therefore, monitoring and evaluation of the steelstresses/strains in the structure are essential issues for structural design and healthy assessment. The currentstudy experimentally investigates the possibility of using fiber Bragg grating (FBG) sensors to measure thesteel strains in PPC beams in the process of fatigue loading. Six full-scale post-tensioned PPC beams wereexposed to fatigue loading. Within the beams, the FBG and resistance strain gauge (RSG) sensors wereindependently bonded onto the surface of tensile reinforcements. A good agreement was found between therecorded results from the two different sensors. Moreover, FBG sensors show relatively good resistance tofatigue loading compared with RSG sensors, indicating that FBG sensors possess the capability forlong-term health monitoring of the tensile reinforcement in PPC structures. Apart from the above findings, itcan also be found that during the fatigue loading, there is stress redistribution between prestressed andnon-prestressed reinforcements, and the residual strain emerges in the non-prestressed reinforcement. Thisphenomenon can bring about an increase of the steel stress in the non-prestressed reinforcement.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001882828
|
oai_dc
|
Development of a dynamic sensing system for civil revolving structures and its field tests in a large revolving auditorium
|
Development of a dynamic sensing system for civil revolving structures and its field tests in a large revolving auditorium
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Yaozhi Luo(Zhejiang University); Yanbin Shen(Zhejiang University); Pengcheng Yang(Zhejiang University); Feng Yu(Zhejiang University); Zhouneng Zhong(Zhejiang Greenton Architectural Design Co., Ltd); Jiangbo Hong(Hanjia Design Group Co., Ltd)"
] |
In civil engineering, revolving structures (RS) are a unique structural form applied in innovative architecture design. Such structures are able to revolve around themselves or along a certain track. However, few studies are dedicated to safety design or health monitoring of RS. In this paper, a wireless dynamic sensing system is developed for RS, and field tests toward a large revolving auditorium are conducted accordingly. At first, a wheel-rail problem is proposed: The internal force redistributes in RS, which is due to wheel-rail irregularity. Then the development of the sensing system for RS is presented. It includes system architecture, network organization, vibrating wire sensor (VWS) nodes and online remote control. To keep the sensor network identifiable during revolving, the addresses of sensor nodes are reassigned dynamically when RS position changes. At last, the system is mounted on a huge outdoor revolving auditorium. Considering the influence of the proposed problem, the RS of the auditorium has been designed conservatively. Two field tests are conducted via the sensing system. In the first test, 2000 people are invited to act as the live load. During the revolving process, data is collected from RS in three different load cases. The other test is the online monitoring for the auditorium during the official performances. In the end, the field-testing result verifies the existence of the wheel-rail problem. The result also indicates the dynamic sensing system is applicable and durable even while RS is rotating.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001882830
|
oai_dc
|
Two-module robotic pipe inspection system with EMATs
|
Two-module robotic pipe inspection system with EMATs
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"이진혁(서울과학기술대학교); 김대현(서울과학기술대학교); 문형필(성균관대학교); Sangchul Han(Sungkyunkwan University); Jaekyu Ahn(Sungkyunkwan University)"
] |
This work introduces a two-module robotic pipe inspection system with ultrasonic NDE device to evaluate the integrity of pipe structures. The proposed robotic platform has high mobility. The two module mobile robot platform overcomes pipe obstacle structures such as elbow, or T-branch joints by cooperative maneuvers. Also, it can climb up the straight pipeline at a fast speed due to the wheel driven mechanism. For inspection of pipe structure, SH-waves generated by EMAT are applied with additional signal processing methods. A wavelet transform is implemented to extract a meaningful and specific signal from the superposed SH-wave signals. Intensity ratio which is normalized the defect signals intensity by the maximum intensity of directly transmitted signals in the wavelet transforms spectrum is applied to evaluate defects quantitatively. It is experimentally verified that the robotic ultrasonic inspection system with EMAT is capable of non-destructive inspection and evaluation of defects in pipe structure successfully by applying signal processing method based on wavelet transform.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001882800
|
oai_dc
|
Automated condition assessment of concrete bridges with digital imaging
|
Automated condition assessment of concrete bridges with digital imaging
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ram S. Adhikari(Concordia University); Ashutosh Bagchi(Concordia University); Osama Moselhi(Concordia University)"
] |
The reliability of a Bridge management System depends on the quality of visual inspection and the reliable estimation of bridge condition rating. However, the current practices of visual inspection have been identified with several limitations, such as: they are time-consuming, provied incomplete information, and their reliance on inspectors' experience. To overcome such limitations, this paper presents an approach of automating the prediction of condition rating for bridges based on digital image analysis. The proposed methodology encompasses image acquisition, development of 3D visualization model, image processing, and condition rating model. Under this method, scaling defect inconcrete bridge components is considered as a candidate defect and the guidelinges in the Ontario Structure Inspection Manual (OSIM) have been adopted for developing and testing the proposed method. The automated algorighms for scaling depth prediction and mapping of condition ratings are based on training of back propagation neural networks. The result of developed models showed better prediction capability of condition rating over the existing methods such as, Naive Bayes Classifiers and Bagged Decision Tree.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001882833
|
oai_dc
|
A review of rotorcraft Unmanned Aerial Vehicle (UAV) developments and applications in civil engineering
|
A review of rotorcraft Unmanned Aerial Vehicle (UAV) developments and applications in civil engineering
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Peter Liu(Tamkang University); Albert Y. Chen(National Taiwan University); Yin-Nan Huang(National Taiwan University); Jen-Yu Han(National Taiwan University); Jihn-Sung Lai(National Taiwan University); Tzong-Hann Wu(National Taiwan University); Ming-Chang Wen(National Taiwan University); Meng-Han Tsai(National Taiwan University); Shih-Chung Kang(National Taiwan University)"
] |
Civil engineers always face the challenge of uncertainty in planning, building, and maintaininginfrastructure. These works rely heavily on a variety of surveying and monitoring techniques. Unmannedaerial vehicles (UAVs) are an effective approach to obtain information from an additional view, andpotentially bring significant benefits to civil engineering. This paper gives an overview of the state of UAVdevelopments and their possible applications in civil engineering. The paper begins with an introduction toUAV hardware, software, and control methodologies. It also reviews the latest developments in technologiesrelated to UAVs, such as control theories, navigation methods, and image processing. Finally, the paperconcludes with a summary of the potential applications of UAV to seismic risk assessment, transportation,disaster response, construction management, surveying and mapping, and flood monitoring and assessment.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001882794
|
oai_dc
|
Survey on robotics and automation technologies for civil infrastructure
|
Survey on robotics and automation technologies for civil infrastructure
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"명현(한국과학기술원); Yang Wang(Georgia Institute of Technology); Shih-Chung Jessy Kang(National Taiwan University); XiaoQi Chen(University of Canterbury)"
] |
Over the past several decades, substantial amounts of sensors and sensing systems have beendeveloped for civil infrastructure systems. This special issue focuses on state-of-the-art robotics andautomation technologies, including construction automation, robotics, instrumentation, monitoring,inspection, control, and rehabilitation for civil infrastructure. The issue also covers construction informaticssupporting sensing, analysis and design activities needed to operate smart and sustainable civil infrastructure.
Examples include robotic systems applied to civil infrastructure and equipped with various sensingtechnologies, such as optical sensors, laser sensors, wireless sensors, multi-sensor fusion, etc. This specialissue is published in an effort to disseminate current advances of various robotics and automationtechnologies for civil infrastructure and built environment.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001859421
|
oai_dc
|
Effective vibration control of multimodal structures with low power requirement
|
Effective vibration control of multimodal structures with low power requirement
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Thamina Loukil(Ecole Centrale de Lyon); Mohamed Ichchou(Ecole Centrale de Lyon); Olivier Bareille(Ecole Centrale de Lyon); Mohamed Haddar(Ecole Nationale d’Ingenieurs de Sfax)"
] |
In this paper, we investigate the vibration control of multimodal structures and present anefficient control law that requires less energy supply than active strategies. This strategy is called modal global semi-active control and is designed to work as effectively as the active control and consume less power which represents its major limitation. The proposed law is based on an energetic management of theoptimal law such that the controller follows this latter only if there is sufficient energy which will beextracted directly from the system vibrations itself. The control algorithm is presented and validated for acantilever beam structure subjected to external perturbations. Comparisons between the proposed lawperformances and those obtained by independent modal space control (IMSC) and semi-active controlschemes are offered.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001859424
|
oai_dc
|
Vibration control of high-rise buildings for wind: a robust passive and active tuned mass damper
|
Vibration control of high-rise buildings for wind: a robust passive and active tuned mass damper
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Aly Mousaad Aly(Louisiana State University)"
] |
Tuned mass dampers (TMDs) have been installed in many high-rise buildings, to improve their resiliency under dynamic loads. However, high-rise buildings may experience natural frequency changes under ambient temperature fluctuations, extreme wind loads and relative humidity variations. This makes the design of a TMD challenging and may lead to a detuned scenario, which can reduce significantly the performance. To alleviate this problem, the current paper presents a proposed approach for the design of a robust and efficient TMD. The approach accounts for the uncertain natural frequency, the optimization objective and the input excitation. The study shows that robust design parameters can be different from the optimal parameters. Nevertheless, predetermined optimal parameters are useful to attain design robustness. A case study of a high-rise building is executed. The TMD designed with the proposed approach showed its robustness and effectiveness in reducing the responses of high-rise buildings under multidirectional wind. The case study represents an engineered design that is instructive. The results show that shear buildings may be controlled with less effort than cantilever buildings. Structural control performance in high-rise buildings may depend on the shape of the building, hence the flow patterns, as well as the wind direction angle. To further increase the performance of the robust TMD in one lateral direction, active control using LQG and fuzzy logic controllers was carried out. The performance of the controllers is remarkable in enhancing the response reduction. In addition, the fuzzy logic controller may be more robust than the LQG controller.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001859416
|
oai_dc
|
On the NiTi wires in dampers for stayed cables
|
On the NiTi wires in dampers for stayed cables
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Vicenç Torra(UPC (retired) PRG); Guillem Carreras(UPC (retired) PRG); Sara Casciati(University of Catania); Patrick Terriault(Quebec University)"
] |
Recent studies were dedicated to the realization of measurements on stay-cable samples of different geometry and static conditions as available at several facilities. The elaboration of the acquired data showed a a satisfactory efficacy of the dampers made of NiTi wires in smoothing the cable oscillations. A further attempt to investigate the applicability of the achieved results beyond the specific case-studies represented by the tested cable-stayed samples is herein pursued. Comparative studies are carried out by varying the diameter of the NiTi wire so that similar measurements can be taken also from laboratory steel cables of reduced size. Details of the preparation of the Ni-Ti wires are discussed with particular attention being paid to the suppression of the creep phenomenon. The resulting shape of the hysteretic cycle differs according to the wire diameter, which affects the order of the fitting polynomial to be used when trying toretrieve the experimental results by numerical analyses. For a NiTi wire of given diameter, an estimate of theamount of dissipated energy per cycle is given at low levels of maximum strain, which correspond to afatigue fracture life of the order of millions of cycles. The dissipative capability is affected by both thetemperature and the cycling frequency at which the tests are performed. Such effects are quantified and anageing process is proposed in order to extend the working temperature range of the damper to cold weatherstypical of the winter season in Northern Europe and Canada. A procedure for the simulation of the shapememory alloy behavior in lengthy cables by finite element analysis is eventually outlined.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001859418
|
oai_dc
|
Optimal sensor placement for mode shapes using improved simulated annealing
|
Optimal sensor placement for mode shapes using improved simulated annealing
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"K.H. Tong(Universiti Teknologi); Norhisham Bakhary(Universiti Teknologi); A.B.H. Kueh(Universiti Teknologi); A.Y. Mohd Yassin(Universiti Teknologi)"
] |
Optimal sensor placement techniques play a significant role in enhancing the quality of modal data during the vibration based health monitoring of civil structures, where many degrees of freedom are available despite a limited number of sensors. The literature has shown a shift in the trends for solving such problems, from expansion or elimination approach to the employment of heuristic algorithms. Although these heuristic algorithms are capable of providing a global optimal solution, their greatest drawback is the requirement of high computational effort. Because a highly efficient optimisation method is crucial for better accuracy and wider use, this paper presents an improved simulated annealing (SA) algorithm to solve the sensor placement problem. The algorithm is developed based on the sensor locations‟ coordinate system to allow for the searching in additional dimensions and to increase SA‟s random search performance while minimising the computation efforts. The proposed method is tested on a numerical slab model that consists of two hundred sensor location candidates using three types of objective functions; the determinant of the Fisher information matrix (FIM), modal assurance criterion (MAC), and mean square error (MSE) of mode shapes. Detailed study on the effects of the sensor numbers and cooling factors on the performance of the algorithm are also investigated. The results indicate that the proposed method outperforms conventional SA and Genetic Algorithm (GA) in the search for optimal sensor placement.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001859422
|
oai_dc
|
Recognition of rolling bearing fault patterns and sizes based on two-layer support vector regression machines
|
Recognition of rolling bearing fault patterns and sizes based on two-layer support vector regression machines
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Changqing Shen(City University of Hong Kong); Dong Wang(City University of Hong Kong); Yongbin Liu(University of Science and Technology of China); Peter W. Tse(City University of Hong Kong); Fanrang Kong(University of Science and Technology of China)"
] |
The fault diagnosis of rolling element bearings has drawn considerable research attention in recent years because these fundamental elements frequently suffer failures that could result in unexpected machine breakdowns. Artificial intelligence algorithms such as artificial neural networks (ANNs) and support vector machines (SVMs) have been widely investigated to identify various faults. However, as the useful life of a bearing deteriorates, identifying early bearing faults and evaluating their sizes of development are necessary for timely maintenance actions to prevent accidents. This study proposes a new two-layerstructure consisting of support vector regression machines (SVRMs) to recognize bearing fault patterns and track the fault sizes. The statistical parameters used to track the fault evolutions are first extracted to condense original vibration signals into a few compact features. The extracted features are then used to train the proposed two-layer SVRMs structure. Once these parameters of the proposed two-layer SVRMs structure are determined, the features extracted from other vibration signals can be used to predict theunknown bearing health conditions. The effectiveness of the proposed method is validated by experimental datasets collected from a test rig. The results demonstrate that the proposed method is highly accurate in differentiating between fault patterns and determining their fault severities. Further, comparisons are performed to show that the proposed method is better than some existing methods.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001859419
|
oai_dc
|
Applications of bridge information modeling in bridges life cycle
|
Applications of bridge information modeling in bridges life cycle
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Mohamed M. Marzouk(Cairo University); Mohamed Hisham(Cairo University); Khalid Al-Gahtani(King Saud University)"
] |
The purpose of this paper is to present an Integrated Life Cycle Bridge Information Modeling that can be used throughout different phases of the bridge life cycle including: design, construction, and operation and maintenance phases. Bridge Information Modeling (BrIM) has become an effective tool in bridge engineering and construction. It has been used in obtaining accurate shop drawings, cost estimation, and visualization. In this paper, BrIM is used as an integrated tool for bridges life cycle information modeling. In the design phase, BrIM model can be used in obtaining optimum construction methods andperforming structural advanced analysis. During construction phase, the model selects the appropriate locations for mobile cranes, monitors the status of precast components, and controls documents. Whereas, it acts as a tool for bridge management system in operation and maintenance phase. The paper provides a detailed description for each use of BrIM model in design, construction, and operation and maintenance phases of bridges. It is proven that BrIM is an effective tool for bridge management systems throughout theirlife phases.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001859420
|
oai_dc
|
Investigation of the semi-active electromagnetic damper
|
Investigation of the semi-active electromagnetic damper
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Morteza Montazeri-Gh(IUST); Omid Kavianipour(IUST)"
] |
In this paper, the electromagnetic damper (EMD), which is composed of a permanent-magnet rotary DC motor, a ball screw and a nut, is considered to be analyzed as a semi-active damper. The main objective pursued in the paper is to study the two degrees of freedom (DOF) model of the semi-active electromagnetic suspension system (SAEMSS) performance and energy regeneration controlled by on-off and continuous damping control strategies. The nonlinear equations of the SAEMSS must therefore be extracted. The effects of the EMD characteristics on ride comfort, handling performance and road holdingfor the passive electromagnetic suspension system (PEMSS) are first analyzed and damping control strategies effects on the SAEMSS performance and energy regeneration are investigated next. The results obtained from the simulation show that the SAEMSS provides better performance and more energy regeneration than the PEMSS. Moreover, the results reveal that the on-off hybrid control strategy leads to better performance in comparison with the continuous skyhook control strategy, however, the energy regeneration of the continuous skyhook control strategy is more than that of the on-off hybrid controlstrategy (except for on-off skyhook control strategy).
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001859415
|
oai_dc
|
Sensor placement driven by a model order reduction (MOR) reasoning
|
Sensor placement driven by a model order reduction (MOR) reasoning
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Fabio Casciati(University of Pavia); Lucia Faravelli(University of Pavia)"
] |
Given a body undergoing a stress-strain status as consequence of external excitations, sensors can be deployed on the accessible lateral surface of the body. The sensor readings are regarded as input of a numerical model of reduced order (i.e., the number of sensors is lower than the number of the state variables the full model would require). The goal is to locate the sensors in such a way to minimize the deviations from the response of the true (full) model. One adopts either accelerometers as sensors or devices reading relative displacements. Two applications are studied: a plane frame is first investigated; the focus is eventually on a 3D body.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001859417
|
oai_dc
|
Dynamic analysis of a historical monument: retrofit using shape memory alloy wires
|
Dynamic analysis of a historical monument: retrofit using shape memory alloy wires
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Karim Hamdaoui(University of Tlemcen); Zahira Benadla(University of Tlemcen)"
] |
The effectiveness of using the advanced seismic protection technology based on shape memoryalloy (SMA) dampers to preserve a historical minaret is investigated. The proposed studied case, the minaretof Mansourah, is a seven century old minaret located in Tlemcen, Algeria. Its original height was of 47m,while nowadays, the monument is half destructed and its current height reaches the 40m. The proposedseismic retrofit is based on the technique that utilizes SMA wires as dampers for the upper flexible part ofthe minaret. The effectiveness of the proposed technique is numerically evaluated via non-linear finiteelement analysis using the structural software ANSYS. The effectiveness of the proposed device inmitigating the seismic hazard is demonstrated by the effective reduction in its dynamic response.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002100735
|
oai_dc
|
Seismic performance of prefabricated bridge columns with combination of continuous mild reinforcements and partially unbonded tendons
|
Seismic performance of prefabricated bridge columns with combination of continuous mild reinforcements and partially unbonded tendons
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Koem Chandara(Chung-Ang University); Shim Chang-Su(Chung-Ang University); Park Sung-Jun(Chung-Ang University)"
] |
Prefabricated bridge substructures provide new possibility for designers in terms of efficiency of creativity, fast construction, geometry control and cost. Even though prefabricated bridge columns are widely adopted as a substructure system in the bridge construction project recently, lack of deeper understanding of the seismic behavior of prefabricated bridge substructures cause much concern on their performance in high seismic zones. In this paper, experimental research works are presented to verify enhanced design concepts of prefabricated bridge piers. Integration of precast segments was done with continuity of axial prestressing tendons and mild reinforcing bars throughout the construction joints. Cyclic tests were conducted to investigate the effects of the design parameters on seismic performance. An analytical method for moment-curvature analysis of prefabricated bridge columns is conducted in this study. The method is validated through comparison with experimental results and the fiber model analysis. A parametric study is conducted to observe the seismic behavior of prefabricated bridge columns using the analytical study based on strain compatibility method. The effects of continuity of axial steel and tendon, and initial prestressing level on the load-displacement response characteristics, i.e., the strain of axial mild steels and posttensioned tendon at fracture and concrete crushing strain at the extreme compression fiber are investigated. The analytical study shows the layout of axial mild steels and posttensioned tendons in this experiment is the optimized arrangement for seismic performance.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002100738
|
oai_dc
|
New emerging surface treatment of hybrid GFRP bar for stronger durability of concrete structures
|
New emerging surface treatment of hybrid GFRP bar for stronger durability of concrete structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"박철우(강원대학교); Young-Hwan Park(Korea Institute of Construction Technology); Seungwon Kim(Kangwon National University); Minkwan Ju(Kangwon National University)"
] |
In this study, an innovative and smart glass fiber-reinforced polymer (GFRP) hybrid bar was developed for stronger durability of concrete structures. As comparing with the conventional GFRP bar, the smart GFRP Hybrid bar can promise to enhance the modulus of elasticity so that it makes the cracking reduced than the case when the conventional GFRP bar is used. Besides, the GFRP Hybrid bar can effectively resist the corrosion of conventional steel bar by the GFRP outer surface on the steel bar. In order to verify the bond performance of the GFRP hybrid bar for structural reinforcement, uniaxial pull-out test was conducted. The variables were the bar diameter and the number of strands and pitch of the fiber ribs. Tensile tests showed a excellent increase in the modulus of elasticity, 152.1 GPa, as compared to that of the pure GFRP bar (50 GPa). The stress–strain curve was bi-linear, so that the ductile performance could be obtained. For the bond test, the entire GFRP hybrid bar test specimens failed in concrete splitting due to higher shear strength resulting in concrete crushing as a function of bar deformation. Investigation revealed that an increase in the number of strands of fiber ribs enhanced the bond strength, and the pitch guaranteed the bond strength of D19 (D16) bar specimens may be around 13.4 mm. For a comparative study using two representative code equations, the ACI 440 1R-15 equation is regarded as more suitable for predicting the bond strength of GFRP hybrid bars, whereas the CSA S806-12 prediction is considered too conservative and is largely influenced by the bar diameter. For further study, various geometrical and material properties such as concrete cover, cross-sectional ratio, and surface treatment should be considered.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002100739
|
oai_dc
|
Self-adaptive sampling for sequential surrogate modeling of time-consuming finite element analysis
|
Self-adaptive sampling for sequential surrogate modeling of time-consuming finite element analysis
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Hyung-Jo Jung(Korea Advanced Institute of Science and Technolog); Seung-Seop Jin(Korea Advanced Institute of Science and)"
] |
This study presents a new approach of surrogate modeling for time-consuming finite element analysis. A surrogate model is widely used to reduce the computational cost under an iterative computational analysis. Although a variety of the methods have been widely investigated, there are still difficulties in surrogate modeling from a practical point of view: (1) How to derive optimal design of experiments (i.e., the number of training samples and their locations); and (2) diagnostics of the surrogate model. To overcome these difficulties, we propose a sequential surrogate modeling based on Gaussian process model (GPM) with self-adaptive sampling. The proposed approach not only enables further sampling to make GPM more accurate, but also evaluates the model adequacy within a sequential framework. The applicability of the proposed approach is first demonstrated by using mathematical test functions. Then, it is applied as a substitute of the iterative finite element analysis to Monte Carlo simulation for a response uncertainty analysis under correlated input uncertainties. In all numerical studies, it is successful to build GPM automatically with the minimal user intervention. The proposed approach can be customized for the various response surfaces and help a less experienced user save his/her efforts.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002100765
|
oai_dc
|
Operation of battery-less and wireless sensor using magnetic resonance based wireless power transfer through concrete
|
Operation of battery-less and wireless sensor using magnetic resonance based wireless power transfer through concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Hoon Sohn(Korean Advanced Institute for Science an); Ji-Min Kim(Korean Advanced Institute for Science an); Minseok Han(Osan University); Hyung Jin Lim(Korean Advanced Institute for Science an); Suyoung Yang(Korean Advanced Institute for Science an)"
] |
Although the deployment of wireless sensors for structural sensing and monitoring is becoming popular, supplying power to these sensors remains as a daunting task. To address this issue, there have been large volume of ongoing energy harvesting studies that aimed to find a way to scavenge energy from surrounding ambient energy sources such as vibration, light and heat. In this study, a magnetic resonance based wireless power transfer (MR-WPT) system is proposed so that sensors inside a concrete structure can be wirelessly powered by an external power source. MR-WPT system offers need-based active power transfer using an external power source, and allows wireless power transfer through 300-mm thick reinforced concrete with 21.34% and 17.29% transfer efficiency at distances of 450 mm and 500 mm, respectively. Because enough power to operate a typical wireless sensor can be instantaneously transferred using the proposed MR-WPT system, no additional energy storage devices such as rechargeable batteries or supercapacitors are required inside the wireless sensor, extending the expected life-span of the sensor.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002100737
|
oai_dc
|
Transfer length of 2400 MPa seven-wire 15.2 mm steel strands in high-strength pretensioned prestressed concrete beam
|
Transfer length of 2400 MPa seven-wire 15.2 mm steel strands in high-strength pretensioned prestressed concrete beam
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jin Kook Kim(POSCO Global R&D Center); Hong Jae Yim(Kyungpook National University); Jun-Mo Yang(POSCO)"
] |
In this study, the transfer length of 2400 MPa, seven-wire high-strength steel strands with a 15.2 mm diameter in pretensioned prestressed concrete (PSC) beams utilizing high strength concrete over 58 MPa at prestress release was evaluated experimentally. 32 specimens, which have the variables of concrete compressive strength, concrete cover depth, and the number of PS strands, were fabricated and corresponding transfer lengths were measured. The strands were released gradually by slowly reducing the pressure in the hydraulic stressing rams. The measured results of transfer length showed that the transfer length decreased as the concrete compressive strength and concrete cover depth increased. The number of strands had a very small effect, and the effect varied with both the concrete cover depth and concrete strength. The results were compared to current design codes and transfer lengths predicted by other researchers. The comparison results showed that the current transfer length prediction models in design codes may be conservatively used for 2400 MPa high-strength strands in high-strength concrete beams exceeding 58 MPa at prestress release.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002100766
|
oai_dc
|
Dynamic displacement estimation by fusing biased high-sampling rate acceleration and low-sampling rate displacement measurements using two-stage Kalman estimator
|
Dynamic displacement estimation by fusing biased high-sampling rate acceleration and low-sampling rate displacement measurements using two-stage Kalman estimator
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Hoon Sohn(Korea Advanced Institute of Science and); 김기영(한국과학기술원); Jaemook Choi(Korea Advanced Institute of Science and); Gunhee Koo(Korea Advanced Institute of Science and)"
] |
In this paper, dynamic displacement is estimated with high accuracy by blending high-sampling rate acceleration data with low-sampling rate displacement measurement using a two-stage Kalman estimator. In Stage 1, the two-stage Kalman estimator first approximates dynamic displacement. Then, the estimator in Stage 2 estimates a bias with high accuracy and refines the displacement estimate from Stage 1. In the previous Kalman filter based displacement techniques, the estimation accuracy can deteriorate due to (1) the discontinuities produced when the estimate is adjusted by displacement measurement and (2) slow convergence at the beginning of estimation. To resolve these drawbacks, the previous techniques adopt smoothing techniques, which involve additional future measurements in the estimation. However, the smoothing techniques require more computational time and resources and hamper real-time estimation. The proposed technique addresses the drawbacks of the previous techniques without smoothing. The performance of the proposed technique is verified under various dynamic loading, sampling rate and noise level conditions via a series of numerical simulations and experiments. Its performance is also compared with those of the existing Kalman filter based techniques.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002100767
|
oai_dc
|
A NoSQL data management infrastructure for bridge monitoring
|
A NoSQL data management infrastructure for bridge monitoring
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Seongwoon Jeong(Stanford University); Yilan Zhang(University of Michigan); Jaemook Choi(University of Michigan); Jerome P. Lynch(University of Michigan); Hoon Sohn(Korea Advanced Institute of Science and); Kincho H. Law(Stanford University)"
] |
Advances in sensor technologies have led to the instrumentation of sensor networks for bridge monitoring and management. For a dense sensor network, enormous amount of sensor data are collected. The data need to be managed, processed, and interpreted. Data management issues are of prime importance for a bridge management system. This paper describes a data management infrastructure for bridge monitoring applications. Specifically, NoSQL database systems such as MongoDB and Apache Cassandra are employed to handle time-series data as well the unstructured bridge information model data. Standard XML-based modeling languages such as OpenBrIM and SensorML are adopted to manage semantically meaningful data and to support interoperability. Data interoperability and integration among different components of a bridge monitoring system that includes on-site computers, a central server, local computing platforms, and mobile devices are illustrated. The data management framework is demonstrated using the data collected from the wireless sensor network installed on the Telegraph Road Bridge, Monroe, MI.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002100736
|
oai_dc
|
Structural behavior of precast concrete deck with ribbed loop joints in a composite bridge
|
Structural behavior of precast concrete deck with ribbed loop joints in a composite bridge
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Dong-Ho Shin(Daewoo Institute of Construction Techno); Chul-Hun Chung(Dankook University); Daewoo Institute of Construction Techno(Daewoo Institute of Construction Techno); Se-Jin Park(Daewoo Institute of Construction Techno); In-Gyu Kim(Daewoo Institute of Construction Techno); Young-Jin Kim(Daewoo Institute of Construction Techno); Tae-Kwan Byun(Dankook University); Myoung-Gu Kang(Dankook University)"
] |
This study is intended to propose a precast bridge deck system, which has ribbed loop joints between the decks and lacks internal tendons to improve the workability of existing precast deck system. A composite bridge deck specimen was fabricated using the proposed precast deck system, and static and fatigue load tests were conducted to evaluate the structural behavior and the crack pattern of the deck. Leakage test of the deck joints was also conducted and finite element analysis was carried out to compare with the test results.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960852
|
oai_dc
|
Application of numerical simulation of submersed rock-berm structure under anchor collision for structural health monitoring of submarine power cables
|
Application of numerical simulation of submersed rock-berm structure under anchor collision for structural health monitoring of submarine power cables
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"나원배(부경대학교); 우진호(부경대학교); 김동하(부경대학교)"
] |
Submersed rock-berm structures are frequently used for protection of underwater lifelines such as pipelines and power cables. During the service life, the rock-berm structure can experience several accidental loads such as anchor collision. The consequences can be severe with a certain level of frequency; hence, the structural responses should be carefully understood for implementing a proper structural health monitoring method. However, no study has been made to quantify the structural responses because it is hard to deal with the individual behavior of each rock. Therefore, this study presents a collision analysis of the submersed rock-berm structure using a finite element software package by facilitating the smoothed-particle hydrodynamics (SPH) method. The analysis results were compared with those obtained from the Lagrange method. Moreover, two types of anchors (stock anchor and stockless anchor), three collision points and two different drop velocities (terminal velocity of each anchor and 5 m/s) were selected to investigate the changes in the responses. Finally, the effect of these parameters (analysis method, anchor type, collision point and drop velocity) on the analysis results was studied. Accordingly, the effectiveness of the SPH method is verified, a safe rock-berm height (over 1 m) is proposed, and a gauge point (0.5 m above the seabed) is suggested for a structural health monitoring implementation.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960837
|
oai_dc
|
Electromechanical impedance-based long-term SHM for jacket-type tidal current power plant structure
|
Electromechanical impedance-based long-term SHM for jacket-type tidal current power plant structure
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"민지영(한국해양과학기술원); 이진학(한국해양과학기술원); 윤정방(울산과학기술원)"
] |
Jacket-type offshore structures are always exposed to severe environmental conditions such as salt, high speed of current, wave, and wind compared with other onshore structures. In spite of the importance of maintaining the structural integrity for an offshore structure, there are few cases to apply a structural health monitoring (SHM) system in practice. The impedance-based SHM is a kind of local SHM techniques and to date, numerous techniques and algorithms have been proposed for local SHM of real-scale structures. However, it still requires a significant challenge for practical applications to compensate unknown environmental effects and to extract only damage features from impedance signals. In this study, the impedance-based SHM was carried out on a 1/20-scaled model of an Uldolmok current power plant structure in Korea under changes in temperature and transverse loadings. Principal component analysis (PCA)-based approach was applied with a conventional damage index to eliminate environmental changes by removing principal components sensitive to them. Experimental results showed that the proposed approach is an effective tool for long-term SHM under significant environmental changes.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960861
|
oai_dc
|
Analysis of three-dimensional thermal gradients for arch bridge girders using long-term monitoring data
|
Analysis of three-dimensional thermal gradients for arch bridge girders using long-term monitoring data
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Guang-Dong Zhou(Hohai University); Huan Zhang(Hohai University); Ting-Hua Yi(Dalian University of Technology); Bin Chen(Zhejiang University of Technology)"
] |
Thermal loads, especially thermal gradients, have a considerable effect on the behaviors of large-scale bridges throughout their lifecycles. Bridge design specifications provide minimal guidance regarding thermal gradients for simple bridge girders and do not consider transversal thermal gradients in wide girder cross-sections. This paper investigates the three-dimensional thermal gradients of arch bridge girders by integrating long-term field monitoring data recorded by a structural health monitoring system, with emphasis on the vertical and transversal thermal gradients of wide concrete-steel composite girders. Based on field monitoring data for one year, the time-dependent characteristics of temperature and three-dimensional thermal gradients in girder cross-sections are explored. A statistical analysis of thermal gradients is conducted, and the probability density functions of transversal and vertical thermal gradients are estimated. The extreme thermal gradients are predicted with a specific return period by employing an extreme value analysis, and the profiles of the vertical thermal gradient are established for bridge design. The transversal and vertical thermal gradients are developed to help engineers understand the thermal behaviors of concrete-steel composite girders during their service periods.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960835
|
oai_dc
|
Experimental investigations on detecting lateral buckling for subsea pipelines with distributed fiber optic sensors
|
Experimental investigations on detecting lateral buckling for subsea pipelines with distributed fiber optic sensors
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jing Zhou(Dalian University of Technology); Xin Feng(Dalian University of Technology); Wenjing Wu(Dalian University of Technology); Xingyu Li(Dalian University of Technology); Xiaowei Zhang(Dalian University of Technology)"
] |
A methodology based on distributed fiber optic sensors is proposed to detect the lateral buckling for subsea pipelines in this study. Uncontrolled buckling may lead to serious consequences for the structural integrity of a pipeline. A simple solution to this problem is to control the formation of lateral buckles among the pipeline. This firms the importance of monitoring the occurrence and evolution of pipeline buckling during the installation stage and long-term service cycle. This study reports the experimental investigations on a method for distributed detection of lateral buckling in subsea pipelines with Brillouin fiber optic sensor. The sensing scheme possesses the capability for monitoring the pipeline over the entire structure. The longitudinal strains are monitored by mounting the Brillouin optical time domain analysis (BOTDA) distributed sensors on the outer surface of the pipeline. Then the bending-induced strain is extracted to detect the occurrence and evolution of lateral buckling. Feasibility of the method was validated by using an experimental program on a small scale model pipe. The results demonstrate that the proposed approach is able to detect, in a distributed manner, the onset and progress of lateral buckling in pipelines. The methodology developed in this study provides a promising tool for assessing the structural integrity of subsea pipelines
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960853
|
oai_dc
|
Sensitivity-based Damage detection in deep water risers using modal parameters: numerical study
|
Sensitivity-based Damage detection in deep water risers using modal parameters: numerical study
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Cheonhong Min(Korea Research Institute of Ships&Ocean Engineerin); Hyungwoo Kim(Korea Research Institute of Ships&Ocean Engineerin); Taekyeong Yeu(Korea Research Institute of Ships&Ocean Engineerin); Sup Hong(Korea Research Institute of Ships&Ocean Engineerin)"
] |
A main goal of this study is to propose a damage detection technique to detect and localize damages of a top-tensioned riser. In this paper, the top-tensioned finite element (FE) model is considered as an analytical model of the riser, and a vibration-based damage detection method is proposed. The present method consists of a FE model updating and damage index method. In order to accomplish the goal of this study, first, a sensitivity-based FE model updating method using natural frequencies and zero frequencies is introduced. Second, natural frequencies and zero frequencies of the axial mode on the top-tensioned riser are estimated by eigenvalue analysis. Finally, the locations and severities of the damages are estimated from the damage index method. Three numerical examples are considered to verify the performance of the proposed method.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960854
|
oai_dc
|
Issues in structural health monitoring for fixed-type offshore structures under harsh tidal environments
|
Issues in structural health monitoring for fixed-type offshore structures under harsh tidal environments
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"정병진(한국해양과학기술원); 박종웅(University of Illinois at Urbana); 심성한(울산과학기술원); 이진학(한국해양과학기술원)"
] |
Previous long-term measurements of the Uldolmok tidal current power plant showed that the structure\'s natural frequencies fluctuate with a constant cycle—i.e., twice a day with changes in tidal height and tidal current velocity. This study aims to improve structural health monitoring (SHM) techniques for offshore structures under a harsh tidal environment like the Uldolmok Strait. In this study, lab-scale experiments on a simplified offshore structure as a lab-scale test structure were conducted in a circulating water channel to thoroughly investigate the causes of fluctuation of the natural frequencies and to validate the displacement estimation method using multimetric data fusion. To this end, the numerical study was additionally carried out on the simplified offshore structure with damage scenarios, and the corresponding change in the natural frequency was analyzed to support the experimental results. In conclusion, (1) the damage that occurred at the foundation resulted in a more significant change in natural frequencies compared with the effect of added mass; moreover, the structural system became nonlinear when the damage was severe; (2) the proposed damage index was able to indicate an approximate level of damage and the nonlinearity of the lab-scale test structure; (3) displacement estimation using data fusion was valid compared with the reference displacement using the vision-based method
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960859
|
oai_dc
|
Parametric identification of a cable-stayed bridge using least square estimation with substructure approach
|
Parametric identification of a cable-stayed bridge using least square estimation with substructure approach
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Hongwei Huang(Tongji University); Limin Sun(Tongji University); Yaohua Yang(Tongji University)"
] |
Parametric identification of structures is one of the important aspects of structural health monitoring. Most of the techniques available in the literature have been proved to be effective for structures with small degree of freedoms. However, the problem becomes challenging when the structure system is large, such as bridge structures. Therefore, it is highly desirable to develop parametric identification methods that are applicable to complex structures. In this paper, the LSE based techniques will be combined with the substructure approach for identifying the parameters of a cable-stayed bridge with large degree of freedoms. Numerical analysis has been carried out for substructures extracted from the 2-dimentional (2D) finite element model of a cable-stayed bridge. Only vertical white noise excitations are applied to the structure, and two different cases are considered where the structural damping is not included or included. Simulation results demonstrate that the proposed approach is capable of identifying the structural parameters with high accuracy without measurement noises.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960860
|
oai_dc
|
Investigation of mode identifiability of a cable-stayed bridge: comparison from ambient vibration responses and from typhoon-induced dynamic responses
|
Investigation of mode identifiability of a cable-stayed bridge: comparison from ambient vibration responses and from typhoon-induced dynamic responses
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Y.Q. Ni(The Hong Kong Polytechnic University); Y.W. Wang(The Hong Kong Polytechnic University); Y.X. Xia(The Hong Kong Polytechnic University)"
] |
Modal identification of civil engineering structures based on ambient vibration measurement has been widely investigated in the past decades, and a variety of output-only operational modal identification methods have been proposed. However, vibration modes, even fundamental low-order modes, are not always identifiable for large-scale structures under ambient vibration excitation. The identifiability of vibration modes, deficiency in modal identification, and criteria to evaluate robustness of the identified modes when applying output-only modal identification techniques to ambient vibration responses were scarcely studied. In this study, the mode identifiability of the cable-stayed Ting Kau Bridge using ambient vibration measurements and the influence of the excitation intensity on the deficiency and robustness in modal identification are investigated with long-term monitoring data of acceleration responses acquired from the bridge under different excitation conditions. It is observed that a few low-order modes, including the second global mode, are not identifiable by common output-only modal identification algorithms under normal ambient excitations due to traffic and monsoon. The deficient modes can be activated and identified only when the excitation intensity attains a certain level (e.g., during strong typhoons). The reason why a few low-order modes fail to be reliably identified under weak ambient vibration excitations and the relation between the mode identifiability and the excitation intensity are addressed through comparing the frequency-domain responses under normal ambient vibration excitations and under typhoon excitations and analyzing the wind speeds corresponding to different response data samples used in modal identification. The threshold value of wind speed (generalized excitation intensity) that makes the deficient modes identifiable is determined.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960857
|
oai_dc
|
A Bayesian approach for vibration-based long-term bridge monitoring to consider environmental and operational changes
|
A Bayesian approach for vibration-based long-term bridge monitoring to consider environmental and operational changes
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chul-Woo Kim(Kyoto University); Tomoaki Morita(Kyoto University); Yoshinobu Oshima(Kyoto University); Kunitomo Sugiura(Kyoto University)"
] |
This study aims to propose a Bayesian approach to consider changes in temperature and vehicle weight as environmental and operational factors for vibration-based long-term bridge health monitoring. The Bayesian approach consists of three steps: step 1 is to identify damage-sensitive features from coefficients of the auto-regressive model utilizing bridge accelerations; step 2 is to perform a regression analysis of the damage-sensitive features to consider environmental and operational changes by means of the Bayesian regression; and step 3 is to make a decision on the bridge health condition based on residuals, differences between the observed and predicted damage-sensitive features, utilizing 95% confidence interval and the Bayesian hypothesis testing. Feasibility of the proposed approach is examined utilizing monitoring data on an in-service bridge recorded over a one-year period. Observations through the study demonstrated that the Bayesian regression considering environmental and operational changes led to more accurate results than that without considering environmental and operational changes. The Bayesian hypothesis testing utilizing data from the healthy bridge, the damage probability of the bridge was judged as no damage.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960855
|
oai_dc
|
Application of model reduction technique and structural subsection technique on optimal sensor placement of truss structures
|
Application of model reduction technique and structural subsection technique on optimal sensor placement of truss structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chenguang Huang(Chinese Academy of Sciences); Lingling Lu(Chinese Academy of Sciences); Lijuan Liao(Chinese Academy of Sciences); Yanpeng Wei(Chinese Academy of Sciences); Yanchi Liu(Chinese Academy of Sciences); Xi Wang(Beijing Jiaotong University)"
] |
An optimal sensor placement (OSP) method based on structural subsection technique (SST) and model reduction technique was proposed for modal identification of truss structures, which was conducted using genetic algorithm (GA). The constraints of GA variables were determined by SST in advance. Subsequently, according to model reduction technique, the optimal group of master degrees of freedom and the optimal objective function value were obtained using GA in a case of the given number of sensors. Correspondingly, the optimal number of sensors was determined according to optimal objective function values in cases of the different number of sensors. The proposed method was applied on a scaled jacket offshore platform to get its optimal number of sensors and the corresponding optimal sensor layout. Then modal kinetic energy and modal assurance criterion were adopted to evaluate vibration energy and mode independence property. The experiment was also conducted to verify the effectiveness of the selected optimal sensor layout. The results showed that experimental modes agreed reasonably well with numerical results. Moreover the influence of the proposed method using different optimal algorithms and model reduction technique on optimal results was also compared. The results showed that the influence was very little.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960856
|
oai_dc
|
Local dynamic characteristics of PZT impedance interface on tendon anchorage under prestress force variation
|
Local dynamic characteristics of PZT impedance interface on tendon anchorage under prestress force variation
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"김정태(부경대학교); Thanh-Canh Huynh(Pukyong National University); Kwang-Suk Lee(Pukyong National University)"
] |
In this study, local dynamic characteristics of mountable PZT interfaces are numerically analyzed to verify their feasibility on impedance monitoring of the prestress-loss in tendon anchorage subsystems. Firstly, a prestressed tendon-anchorage system with mountable PZT interfaces is described. Two types of mountable interfaces which are different in geometric and boundary conditions are designed for impedance monitoring in the tendon-anchorage subsystems. Secondly, laboratory experiments are performed to evaluate the impedance monitoring via the two mountable PZT interfaces placed on the tendon-anchorage under the variation of prestress forces. Impedance features such as frequency-shifts and root-mean-square-deviations are quantified for the two PZT interfaces. Finally, local dynamic characteristics of the two PZT interfaces are numerically analyzed to verify their performances on impedance monitoring at the tendon-anchorage system. For the two PZT interfaces, the relationships between structural parameters and local vibration responses are examined by modal sensitivity analyses.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960862
|
oai_dc
|
Experimental validation of Kalman filter-based strain estimation in structures subjected to non-zero mean input
|
Experimental validation of Kalman filter-based strain estimation in structures subjected to non-zero mean input
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"조수진(Ulsan National Institute of Science and Technology); Rajendra P. Palanisamy(Ulsan National Institute of Science and Technology); 김현준(울산과학기술대학교); 심성한(울산과학기술원)"
] |
Response estimation at unmeasured locations using the limited number of measurements is an attractive topic in the field of structural health monitoring (SHM). Because of increasing complexity and size of civil engineering structures, measuring all structural responses from the entire body is intractable for the SHM purpose; the response estimation can be an effective and practical alternative. This paper investigates a response estimation technique based on the Kalman state estimator to combine multi-sensor data under non-zero mean input excitations. The Kalman state estimator, constructed based on the finite element (FE) model of a structure, can efficiently fuse different types of data of acceleration, strain, and tilt responses, minimizing the intrinsic measurement noise. This study focuses on the effects of (a) FE model error and (b) combinations of multi-sensor data on the estimation accuracy in the case of non-zero mean input excitations. The FE model error is purposefully introduced for more realistic performance evaluation of the response estimation using the Kalman state estimator. In addition, four types of measurement combinations are explored in the response estimation: strain only, acceleration only, acceleration and strain, and acceleration and tilt. The performance of the response estimation approach is verified by numerical and experimental tests on a simply-supported beam, showing that it can successfully estimate strain responses at unmeasured locations with the highest performance in the combination of acceleration and tilt.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960858
|
oai_dc
|
Locating and identifying model-free structural nonlinearities and systems using incomplete measured structural responses
|
Locating and identifying model-free structural nonlinearities and systems using incomplete measured structural responses
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Lijun Liu(Xiamen University); Ying Lei(Xiamen University); Mingyu He(Xiamen University)"
] |
Structural nonlinearity is a common phenomenon encountered in engineering structures under severe dynamic loading. It is necessary to localize and identify structural nonlinearities using structural dynamic measurements for damage detection and performance evaluation of structures. However, identification of nonlinear structural systems is a difficult task, especially when proper mathematical models for structural nonlinear behaviors are not available. In prior studies on nonparametric identification of nonlinear structures, the locations of structural nonlinearities are usually assumed known and all structural responses are measured. In this paper, an identification algorithm is proposed for locating and identifying model-free structural nonlinearities and systems using incomplete measurements of structural responses. First, equivalent linear structural systems are established and identified by the extended Kalman filter (EKF). The locations of structural nonlinearities are identified. Then, the model-free structural nonlinear restoring forces are approximated by power series polynomial models. The unscented Kalman filter (UKF) is utilized to identify structural nonlinear restoring forces and structural systems. Both numerical simulation examples and experimental test of a multi-story shear building with a MR damper are used to validate the proposed algorithm.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001960836
|
oai_dc
|
Structural identification of gravity-type caisson structure via vibration feature analysis
|
Structural identification of gravity-type caisson structure via vibration feature analysis
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"김정태(부경대학교); 이소영(부경대학교); Thanh-Canh Huynh(Pukyong National University)"
] |
In this study, a structural identification method is proposed to assess the integrity of gravity-type caisson structures by analyzing vibration features. To achieve the objective, the following approaches are implemented. Firstly, a simplified structural model with a few degrees-of-freedom (DOFs) is formulated to represent the gravity-type caisson structure that corresponds to the sensors\' DOFs. Secondly, a structural identification algorithm based on the use of vibration characteristics of the limited DOFs is formulated to fine-tune stiffness and damping parameters of the structural model. Finally, experimental evaluation is performed on a lab-scaled gravity-type caisson structure in a 2-D wave flume. For three structural states including an undamaged reference, a water-level change case, and a foundation-damage case, their corresponding structural integrities are assessed by identifying structural parameters of the three states by fine-tuning frequency response functions, natural frequencies and damping factors.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002089821
|
oai_dc
|
Mode identifiability of a multi-span cable-stayed bridge utilizing stabilization diagram and singular values
|
Mode identifiability of a multi-span cable-stayed bridge utilizing stabilization diagram and singular values
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"C.W. Kim(Kyoto University); Y. Goi(Kyoto University)"
] |
This study investigates the mode identifiability of a multi-span cable-stayed bridge in terms of a benchmark study using stabilization diagrams of a system model identified using stochastic subspace identification (SSI). Cumulative contribution ratios (CCRs) estimated from singular values of system models under different wind conditions were also considered. Observations revealed that wind speed might influence the mode identifiability of a specific mode of a cable-stayed bridge. Moreover the cumulative contribution ratio showed that the time histories monitored during strong winds, such as those of a typhoon, can be modeled with less system order than under weak winds. The blind data Acc 1 and Acc 2 were categorized as data obtained under a typhoon. Blind data Acc 3 and Acc 4 were categorized as data obtained under wind conditions of critical wind speeds around 7.5 m/s. Finally, blind data Acc 5 and Acc 6 were categorized as data measured under weak wind conditions.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002089838
|
oai_dc
|
Wind and traffic-induced variation of dynamic characteristics of a cable-stayed bridge – benchmark study
|
Wind and traffic-induced variation of dynamic characteristics of a cable-stayed bridge – benchmark study
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jae-Hyung Park(Pukyong National University); Thanh-Canh Huynh(Pukyong National University); Kwang-Suk Lee(Pukyong National University); Jeong-Tae Kim(Pukyong National University)"
] |
A benchmark problem for modal identification of a cable-stayed bridge was proposed by a research team at Hong Kong Polytechnic University. By taking an instrumented cable-stayed bridge as a test bed, nineteen sets of vibration records with known/unknown excitations were provided to invited researchers. In this paper, the vibration responses of the bridge under a series of excitation conditions are examined to estimate the wind and traffic-induced variations of its dynamic characteristics. Firstly, two output-only experimental modal identification methods are selected. Secondly, the bridge and its monitoring system are described and the nineteen sets of vibration records are analyzed in time-domain and frequency-domain. Excitations sources of blind datasets are predicted based on the analysis of excitation conditions of known datasets. Thirdly, modal parameters are extracted by using the two selected output-only modal identification methods. The identified modal parameters are examined with respect to at least two different conditions such as traffic- and typhoon-induced loadings. Finally, the typhoon-induced effects on dynamic characteristics of the bridge are estimated by analyzing the relationship between the wind velocity and the modal parameters.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002089825
|
oai_dc
|
Modal identifiability of a cable-stayed bridge using proper orthogonal decomposition
|
Modal identifiability of a cable-stayed bridge using proper orthogonal decomposition
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Y.Q. Ni(The Hong Kong Polytechnic University); M. Li(The Hong Kong Polytechnic University)"
] |
The recent research on proper orthogonal decomposition (POD) has revealed the linkage between proper orthogonal modes and linear normal modes. This paper presents an investigation into the modal identifiability of an instrumented cable-stayed bridge using an adapted POD technique with a band-pass filtering scheme. The band-pass POD method is applied to the datasets available for this benchmark study, aiming to identify the vibration modes of the bridge and find out the so-called deficient modes which are unidentifiable under normal excitation conditions. It turns out that the second mode of the bridge cannot be stably identified under weak wind conditions and is therefore regarded as a deficient mode. To judge if the deficient mode is due to its low contribution to the structural response under weak wind conditions, modal coordinates are derived for different modes by the band-pass POD technique and an energy participation factor is defined to evaluate the energy participation of each vibration mode under different wind excitation conditions. From the non-blind datasets, it is found that the vibration modes can be reliably identified only when the energy participation factor exceeds a certain threshold value. With the identified threshold value, modal identifiability in use of the blind datasets from the same structure is examined.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002089828
|
oai_dc
|
Automated identification of the modal parameters of a cable-stayed bridge: Influence of the wind conditions
|
Automated identification of the modal parameters of a cable-stayed bridge: Influence of the wind conditions
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Filipe Magalhães(University of Porto (FEUP)); Álvaro Cunha(University of Porto (FEUP))"
] |
This paper was written in the context of a benchmark study promoted by The Hong Kong Polytechnic University using data samples collected in an instrumented cable-stayed bridge. The main goal of the benchmark test was to study the identification of the bridge modes of vibration under different wind conditions. In this contribution, the tools developed at ViBest/FEUP for automated data processing of setups collected by dynamic monitoring systems are presented and applied to the data made available in the context of the benchmark study. The applied tools are based on parametric output only modal identification methods combined with clustering algorithms. The obtained results demonstrate that the proposed algorithms succeeded to automatically identify the modes with relevant contribution for the bridge response under different wind conditions.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002089817
|
oai_dc
|
Mode identifiability of a cable-stayed bridge under different excitation conditions assessed with an improved algorithm based on stochastic subspace identification
|
Mode identifiability of a cable-stayed bridge under different excitation conditions assessed with an improved algorithm based on stochastic subspace identification
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Wen-Hwa Wu(National Yunlin University of Science and Technology); Sheng-Wei Wang(National Yunlin University of Science and Technology); Chien-Chou Chen(National Yunlin University of Science and Technology); Gwolong Lai(National Yunlin University of Science and Technology)"
] |
Deficient modes that cannot be always identified from different sets of measurement data may exist in the application of operational modal analysis such as the stochastic subspace identification techniques in large-scale civil structures. Based on a recent work using the long-term ambient vibration measurements from an instrumented cable-stayed bridge under different wind excitation conditions, a benchmark problem is launched by taking the same bridge as a test bed to further intensify the exploration of mode identifiability. For systematically assessing this benchmark problem, a recently developed SSI algorithm based on an alternative stabilization diagram and a hierarchical sifting process is extended and applied in this research to investigate several sets of known and blind monitoring data. The evaluation of delicately selected cases clearly distinguishes the effect of traffic excitation on the identifiability of the targeted deficient mode from the effect of wind excitation. An additional upper limit for the vertical acceleration amplitude at deck, mainly induced by the passing traffic, is subsequently suggested to supplement the previously determined lower limit for the wind speed. Careful inspection on the shape vector of the deficient mode under different excitation conditions leads to the postulation that this mode is actually induced by the motion of the central tower. The analysis incorporating the tower measurements solidly verifies this postulation by yielding the prevailing components at the tower locations in the extended mode shape vector. Moreover, it is also confirmed that this mode can be stably identified under all the circumstances with the addition of tower measurements. An important lesson learned from this discovery is that the problem of mode identifiability usually comes from the lack of proper measurements at the right locations.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002089833
|
oai_dc
|
Investigation of modal identification and modal identifiability of a cable-stayed bridge with Bayesian framework
|
Investigation of modal identification and modal identifiability of a cable-stayed bridge with Bayesian framework
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ka-Veng Yuen(University of Macau); Sin-Chi Kuok(Cornell University)"
] |
In this study, the Bayesian probabilistic framework is investigated for modal identification and modal identifiability based on the field measurements provided in the structural health monitoring benchmark problem of an instrumented cable-stayed bridge named Ting Kau Bridge (TKB). The comprehensive structural health monitoring system on the cable-stayed TKB has been operated for more than ten years and it is recognized as one of the best test-beds with readily available field measurements. The benchmark problem of the cable-stayed bridge is established to stimulate investigations on modal identifiability and the present paper addresses this benchmark problem from the Bayesian prospective. In contrast to deterministic approaches, an appealing feature of the Bayesian approach is that not only the optimal values of the modal parameters can be obtained but also the associated estimation uncertainty can be quantified in the form of probability distribution. The uncertainty quantification provides necessary information to evaluate the reliability of parametric identification results as well as modal identifiability. Herein, the Bayesian spectral density approach is conducted for output-only modal identification and the Bayesian model class selection approach is used to evaluate the significance of different modes in modal identification. Detailed analysis on the modal identification and modal identifiability based on the measurements of the bridge will be presented. Moreover, the advantages and potentials of Bayesian probabilistic framework on structural health monitoring will be discussed.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002089840
|
oai_dc
|
Optimal reduction from an initial sensor deployment along the deck of a cable-stayed bridge
|
Optimal reduction from an initial sensor deployment along the deck of a cable-stayed bridge
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"F. Casciati(University of Pavia); S. Casciati(University of Catania at Siracusa); L. Elia(University of Pavia); L. Faravelli(University of Pavia)"
] |
The ambient vibration measurement is an output-data-only dynamic testing where natural excitations are represented, for instance, by winds and typhoons. The modal identification involving output-only measurements requires the use of specific modal identification techniques. This paper presents the application of a reliable method (the Stochastic Subspace Identification – SSI) implemented in a general purpose software. As a criterion toward the robustness of identified modes, a bio-inspired optimization algorithm, with a highly nonlinear objective function, is introduced in order to find the optimal deployment of a reduced number of sensors across a large civil engineering structure for the validation of its modal identification. The Ting Kau Bridge (TKB), one of the longest cable-stayed bridges situated in Hong Kong, is chosen as a case study. The results show that the proposed method catches eigenvalues and eigenvectors even for a reduced number of sensors, without any significant loss of accuracy.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002089836
|
oai_dc
|
Mode identifiability of a cable-stayed bridge based on a Bayesian method
|
Mode identifiability of a cable-stayed bridge based on a Bayesian method
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Feng-Liang Zhang(Tongji University); Yi-Qing Ni(The Hong Kong Polytechnic University); Yan-Chun Ni(Tongji University)"
] |
Modal identification based on ambient vibration data has attracted extensive attention in the past few decades. Since the excitation for ambient vibration tests is mainly from the environmental effects such as wind and traffic loading and no artificial excitation is applied, the signal to noise (s/n) ratio of the data acquired plays an important role in mode identifiability. Under ambient vibration conditions, certain modes may not be identifiable due to a low s/n ratio. This paper presents a study on the mode identifiability of an instrumented cable-stayed bridge with the use of acceleration response data measured by a long-term structural health monitoring system. A recently developed fast Bayesian FFT method is utilized to perform output-only modal identification. In addition to identifying the most probable values (MPVs) of modal parameters, the associated posterior uncertainties can be obtained by this method. Likewise, the power spectral density of modal force can be identified, and thus it is possible to obtain the modal s/n ratio. This provides an efficient way to investigate the mode identifiability. Three groups of data are utilized in this study: the first one is 10 data sets including six collected under normal wind conditions and four collected during typhoons; the second one is three data sets with wind speeds of about 7.5 m/s; and the third one is some blind data. The first two groups of data are used to perform ambient modal identification and help to estimate a critical value of the s/n ratio above which the deficient mode is identifiable, while the third group of data is used to perform verification. A couple of fundamental modes are identified, including the ones in the vertical and transverse directions respectively and coupled in both directions. The uncertainty and s/n ratio of the deficient mode are investigated and discussed. A critical value of the modal s/n ratio is suggested to evaluate the mode identifiability of the deficient mode. The work presented in this paper could provide a base for the vibration-based condition assessment in future.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002107890
|
oai_dc
|
Application of Eringen\'s nonlocal elasticity theory for vibration analysis of rotating functionally graded nanobeams
|
Application of Eringen\'s nonlocal elasticity theory for vibration analysis of rotating functionally graded nanobeams
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Farzad Ebrahimi(Imam Khomeini International University); Navvab Shafiei(Imam Khomeini International University)"
] |
In the present study, for first time the size dependent vibration behavior of a rotating functionally graded (FG) Timoshenko nanobeam based on Eringen\'s nonlocal theory is investigated. It is assumed that the physical and mechanical properties of the FG nanobeam are varying along the thickness based on a power law equation. The governing equations are determined using Hamilton\'s principle and the generalized differential quadrature method (GDQM) is used to obtain the results for cantilever boundary conditions. The accuracy and validity of the results are shown through several numerical examples. In order to display the influence of size effect on first three natural frequencies due to change of some important nanobeam parameters such as material length scale, angular velocity and gradient index of FG material, several diagrams and tables are presented. The results of this article can be used in designing and optimizing elastic and rotary type nano-electro-mechanical systems (NEMS) like nano-motors and nano-robots including rotating parts.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002107884
|
oai_dc
|
Non-contact damage monitoring technique for FRP laminates using guided waves
|
Non-contact damage monitoring technique for FRP laminates using guided waves
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Mohit Garg(Thapar University); Shruti Sharma(Thapar University); 등록되었습니다.(Thapar University); Rajeev Mehta(Thapar University)"
] |
A non-contact, in-situ and non-invasive technique for health monitoring of submerged fiber reinforced polymers (FRP) laminates has been developed using ultrasonic guided waves. A pair of mobile transducers at specific angles of incidence to the submerged FRP specimen was used to excite Lamb wave modes. Lamb wave modes were used for comprehensive inspection of various types of manufacturing defects like air gaps and missing epoxy, introduced during manufacturing of FRP using Vacuum Assisted Resin Infusion Molding (VARIM). Further service induced damages like notches and surface defects were also studied and evaluated using guided waves. Quantitative evaluation of transmitted ultrasonic signal in defect ridden FRPs vis-à-vis healthy signal has been used to relate the extent of damage in FRPs. The developed technique has the potential to develop into a quick, real time health monitoring tool for judging the service worthiness of FRPs.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002107872
|
oai_dc
|
A novel method to specify pattern recognition of actuators for stress reduction based on Particle swarm optimization method
|
A novel method to specify pattern recognition of actuators for stress reduction based on Particle swarm optimization method
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Javad Jafari Fesharaki(Islamic Azad University); Sa'id Golabi(University of Kashan)"
] |
This paper is focused on stiffness ratio effect and a new method to specify the best pattern of piezoelectric patches placement around a hole in a plate under tension to reduce the stress concentration factor. To investigate the stiffness ratio effect, some different values greater and less than unity are considered. Then a python code is developed by using particle swarm optimization algorithm to specify the best locations of piezoelectric actuators around the hole for each stiffness ratio. The results show that, there is a line called \"reference line\" for each plate with a hole under tension, which can guide the location of actuator patches in plate to have the maximum stress concentration reduction. The reference line also specifies that actuators should be located horizontally or vertically. This reference line is located at an angle of about 65 degrees from the stress line in plate. Finally two experimental tests for two different locations of the patches with various voltages are carried out for validation of the results.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002107874
|
oai_dc
|
Synergy of monitoring and security
|
Synergy of monitoring and security
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Sara Casciati(University of Catania at Siracusa); Zhi Cong Chen(Fuzhou University); Lucia Faravelli(University of Pavia); Michele Vece(University of Pavia)"
] |
An ongoing research project is devoted to the design and implementation of a satellite based asset tracking for supporting emergency management in crisis operations. Due to the emergency environment, one has to rely on a low power consumption wireless communication. Therefore, the communication hardware and software must be designed to match requirements, which can only be foreseen at the level of more or less likely scenarios. The latter aspect suggests a deep use of a simulator (instead of a real network of sensors) to cover extreme situations. The former power consumption remark suggests the use of a minimal computer (Raspberry Pi) as data collector.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002107868
|
oai_dc
|
Performance assessment of buildings isolated with S-FBI system under near-fault earthquakes
|
Performance assessment of buildings isolated with S-FBI system under near-fault earthquakes
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Osman E. Ozbulut(University of Virginia); Baikuntha Silwal(University of Virginia)"
] |
This study investigates the optimum design parameters of a superelastic friction base isolator (S-FBI) system through a multi-objective genetic algorithm to improve the performance of isolated buildings against near-fault earthquakes. The S-FBI system consists of a flat steel-PTFE sliding bearing and superelastic NiTi shape memory alloy (SMA) cables. Sliding bearing limits the transfer of shear across the isolation interface and provides damping from sliding friction. SMA cables provide restoring force capability to the isolation system together with additional damping characteristics. A three-story building is modeled with S-FBI isolation system. Multiple-objective numerical optimization that simultaneously minimizes isolation-level displacements and superstructure response is carried out with a genetic algorithm in order to optimize S-FBI system. Nonlinear time history analyses of the building with optimal S-FBI system are performed. A set of 20 near-fault ground motion records are used in numerical simulations. Results show that S-FBI system successfully control response of the buildings against near-fault earthquakes without sacrificing in isolation efficacy and producing large isolation-level deformations.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002107878
|
oai_dc
|
Free and transient responses of linear complex stiffness system by Hilbert transform and convolution integral
|
Free and transient responses of linear complex stiffness system by Hilbert transform and convolution integral
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"S.H. Bae(Pusan National University); 조진래(홍익대학교); 정의봉(부산대학교)"
] |
This paper addresses the free and transient responses of a SDOF linear complex stiffness system by making use of the Hilbert transform and the convolution integral. Because the second-order differential equation of motion having the complex stiffness give rise to the conjugate complex eigen values, its time-domain analysis using the standard time integration scheme suffers from the numerical instability and divergence. In order to overcome this problem, the transient response of the linear complex stiffness system is obtained by the convolution integral of a green function which corresponds to the unit-impulse free vibration response of the complex system. The damped free vibration of the complex system is theoretically derived by making use of the state-space formulation and the Hilbert transform. The convolution integral is implemented by piecewise-linearly interpolating the external force and by superimposing the transient responses of discretized piecewise impulse forces. The numerical experiments are carried out to verify the proposed time-domain analysis method, and the correlation between the real and imaginary parts in the free and transient responses is also investigated.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002107866
|
oai_dc
|
The smart PFD with LRB for seismic protection of the horizontally curved bridge
|
The smart PFD with LRB for seismic protection of the horizontally curved bridge
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"N.P. Kataria(Indian Institute of Technology Bombay); R.S. Jangid(Indian Institute of Technology Bombay)"
] |
Recently, number of smart material are investigated and widely used in civil construction and other industries. Present study investigates the application of smart semi-active piezoelectric friction damper (PFD) made with piezoelectric material for the seismic control of the horizontally curved bridge isolated with lead rubber bearing (LRB). The main aim of the study is to investigate the effectiveness of hybrid system and to find out the optimum parameters of PFD for seismic control of the curved bridge. The selected curved bridge is a continuous three-span concrete box girder supported on pier and rigid abutment. The PFD is located between the deck and abutments or piers in chord and radial directions. The bridge is excited with four different earthquake ground motions with all three components (i.e. two horizontal and a vertical) having different characteristics. It is observed that the use of semi-active PFD with LRB is quite effective in controlling the response of the curved bridge as compared with passive system. The incorporation of the smart damper requiring small amount of energy in addition with an isolation system can be used for effective control the curved bridge against the dynamic loading.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002107888
|
oai_dc
|
A single slotted morphing flap based on SMA technology
|
A single slotted morphing flap based on SMA technology
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Salvatore Ameduri(Centro Italiano Ricerche Aerospaziali); Antonio Concilio(Centro Italiano Ricerche Aerospaziali); Rosario Pecora(Università degli Studi di Napoli Federico II); Dimitrios Karagiannis(INASCO Hellas Co)"
] |
In this paper, the activities carried out within the EU funded Clean Sky Joint Technology Initiative (JTI GRA) Project and aimed at developing a morphing flap, are illustrated. The reference device is a regional aircraft single slotted flap, enhanced with deforming capabilities to obtain improved hyper-lift performance. The design started with the identification of the internal architecture, intended to allow camber variations. A concentrated-hinge architecture was selected, for its ability to fit different curvatures and for the possibility of easily realizing an \"armadillo-like\" configuration, then avoiding the use of a complicate deformable skin. The flap layout is made of segmented ribs, elastically hinged each other and span-wise connected by conventional spars. Relative rotations of the rib elements are forced by SMA structural actuators, i.e., cooperating in the external loads absorption. Super-elastic SMA are used to make up recovery elastic elements, necessary to regain the original shape after activation. These further elements in turn contribute to the overall flap rigidity. After assessing the hinge number and the size of the SMA active and passive elements, the advanced design phase was dealt with. It was aimed at solving manufacturing issues and producing the executive drawings. The realized demonstrator was finally tested in lab conditions to prove its functionality in terms of whether target shape actuation or attained shape preservation under loads. On the basis of the numerical results and the experimental outcomes, precious hints were obtained for further developments of the concept.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002107881
|
oai_dc
|
A controllability-based formulation for the topology optimization of smart structures
|
A controllability-based formulation for the topology optimization of smart structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Juliano F. Gonçalves(Federal University of Rio Grande do Sul); Jun S.O. Fonseca(Federal University of Rio Grande do Sul); Otávio A.A. Silveira(Federal University of Santa Catarina)"
] |
This work presents a methodology to distribute piezoelectric material for structural vibration active control. The objective is to design controlled structures with actuators which maximizes the system controllability. A topology optimization was formulated in order to distribute two material phases in the domain: a passive linear elastic material and an active linear piezoelectric material. The objective is the maximization of the smallest eigenvalue of the system controllability Gramian. Analytical sensitivities for the finite element model are derived for the objective functions and constraints. Results and comparisons with previous works are presented for the vibration control of a two-dimensional short beam.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002075849
|
oai_dc
|
Non-contact surface wave testing of pavements: comparing a rolling microphone array with accelerometer measurements
|
Non-contact surface wave testing of pavements: comparing a rolling microphone array with accelerometer measurements
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Henrik Bjurström(KTH Royal Institute of Technology); Nils Ryden(KTH Royal Institute of Technology); Björn Birgisson(KTH Royal Institute of Technology)"
] |
Rayleigh wave velocity along a straight survey line on a concrete plate is measured in order to compare different non-destructive data acquisition techniques. Results from a rolling non-contact data acquisition system using air-coupled microphones are compared to conventional stationary accelerometer results. The results show a good match between the two acquisition techniques. Rolling measurements were found to provide a fast and reliable alternative to stationary system for stiffness determination. However, the non-contact approach is shown to be sensitive to unevenness of the measured surface. Measures to overcome this disadvantage are discussed and demonstrated using both forward and reverse rolling measurements.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002075857
|
oai_dc
|
Electro-mechanical impedance based monitoring for the setting of cement paste using piezoelectricity sensor
|
Electro-mechanical impedance based monitoring for the setting of cement paste using piezoelectricity sensor
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"이준철(경북대학교); 신성우(부경대학교); 김화중(경북대학교); 이창준(충북대학교)"
] |
The evolution of the electro-mechanical impedance (EMI) of a piezoelectricity (PZT) sensor was investigated to determine the setting times of cement paste in this study. The PZT sensor coated with non-conductive acrylic resin was embedded in fresh cement paste and the EMI signatures were continuously monitored. Vicat needle test and semi-adiabatic calorimetry test were also conducted to validate the EMI sensing technique. Significant changes in the EMI resonance peak magnitude and frequency during the setting period were observed and the setting times determined by EMI sensing technique were relevant to those measured by Vicat needle test and semi-adiabatic calorimetry test.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002075852
|
oai_dc
|
Evaluation of freezing and thawing damage of concrete using a nonlinear ultrasonic method
|
Evaluation of freezing and thawing damage of concrete using a nonlinear ultrasonic method
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"임홍재(경북대학교); 박선종(한국과학기술원); 김재홍(울산과학기술원); 곽효경(한국과학기술원)"
] |
Freezing and thawing cycles induce deterioration and strength degradation of concrete structures. This study presumes that a large quantity of contact-type defects develop due to the freezing and thawing cycles of concrete and evaluates the degree of defects based on a nonlinearity parameter. The nonlinearity parameter was obtained by an impact-modulation technique, one of the nonlinear ultrasonic methods. It is then used as an indicator of the degree of contact-type defects. Five types of damaged samples were fabricated according to different freezing and thawing cycles, and the occurrence of opening or cracks on a micro-scale was visually verified via scanning electron microscopy. Dynamic modulus and wave velocity were also measured for a sensitivity comparison with the obtained nonlinearity parameter. The possibility of evaluating strength degradation was also investigated based on a simple correlation of the experimental results.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002075851
|
oai_dc
|
Air-coupled ultrasonic tomography of solids: 2 Application to concrete elements
|
Air-coupled ultrasonic tomography of solids: 2 Application to concrete elements
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Kerry S. Hall(University Blvd); John S. Popovics(University of Illinois at Urbana-Champaign)"
] |
Applications of ultrasonic tomography to concrete structures have been reported for many years. However, practical and effective application of this tool for nondestructive assessment of internal concrete condition is hampered by time consuming transducer coupling that limits the amount of ultrasonic data that can be collected. This research aims to deploy recent developments in air-coupled ultrasonic measurements of solids, described in Part 1 of this paper set, to concrete in order to image internal inclusions. Ultrasonic signals are collected from concrete samples using a fully air-coupled (contactless) test configuration. These air coupled data are compared to those collected using partial semi-contact and full-contact test configurations. Two samples are considered: a 150 mm diameter cylinder with an internal circular void and a prism with 300 mm x 300 mm square cross-section that contains internal damaged regions and embedded reinforcement. The heterogeneous nature of concrete material structure complicates the application and interpretation of ultrasonic measurements and imaging. Volumetric inclusions within the concrete specimens are identified in the constructed velocity tomograms, but wave scattering at internal interfaces of the concrete disrupts the images. This disruption reduces defect detection accuracy as compared with tomograms built up of data collected from homogeneous solid samples (PVC) that are described in Part 1 of this paper set. Semi-contact measurements provide some improvement in accuracy through higher signal-to-noise ratio while still allowing for reasonably rapid data collection.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002075855
|
oai_dc
|
Monitoring the failure mechanisms of a reinforced concrete beam strengthened by textile reinforced cement using acoustic emission and digital image correlation
|
Monitoring the failure mechanisms of a reinforced concrete beam strengthened by textile reinforced cement using acoustic emission and digital image correlation
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Dimitrios G. Aggelis(Vrije Universiteit Brussel); Svetlana Verbruggen(Vrije Universiteit Brussel); Eleni Tsangouri(Vrije Universiteit Brussel); Tine Tysmans(Vrije Universiteit Brussel); Danny Van Hemelrijck(Vrije Universiteit Brussel)"
] |
One of the most commonly used techniques to strengthen steel reinforced concrete structures is the application of externally bonded patches in the form of carbon fiber reinforced polymers (CFRP) or recently, textile reinforced cements (TRC). These external patches undertake the tensile stress of bending constraining concrete cracking. Development of full-field inspection methodologies for fracture monitoring are important since the reinforcing layers are not transparent, hindering visual observation of the material condition underneath. In the present study acoustic emission (AE) and digital image correlation (DIC) are applied during four-point bending tests of large beams to follow the damage accumulation. AE helps to determine the onset of fracture as well as the different damage mechanisms through the registered shifts in AE rate, location of active sources and change in waveform parameters. The effect of wave propagation distance, which in large components and in-situ can well mask the original information as emitted by the fracture incidents is also discussed. Simultaneously, crucial information is supplied by DIC concerning the moments of stress release of the patches due to debonding, benchmarking the trends monitored by AE. From the point of view of mechanics, conclusions on the reinforcing contribution of the different repair methodologies are also drawn.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002075850
|
oai_dc
|
Air-coupled ultrasonic tomography of solids: 1 Fundamental development
|
Air-coupled ultrasonic tomography of solids: 1 Fundamental development
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Kerry S. Hall(University Blvd); John S. Popovics(University of Illinois at Urbana-Champaign)"
] |
Ultrasonic tomography is a powerful tool for identifying defects within an object or structure. But practical application of ultrasonic tomography to solids is often limited by time consuming transducer coupling. Air-coupled ultrasonic measurements may eliminate the coupling problem and allow for more rapid data collection and tomographic image construction. This research aims to integrate recent developments in air-coupled ultrasonic measurements with current tomography reconstruction routines to improve testing capability. The goal is to identify low velocity inclusions (air-filled voids and notches) within solids using constructed velocity images. Finite element analysis is used to simulate the experiment in order to determine efficient data collection schemes. Comparable air-coupled ultrasonic signals are then collected through homogeneous and isotropic solid (PVC polymer) samples. Volumetric (void) and planar (notch) inclusions within the samples are identified in the constructed velocity tomograms for a variety of transducer configurations. Although there is some distortion of the inclusions, the experimentally obtained tomograms accurately indicate their size and location. Reconstruction error values, defined as misidentification of the inclusion size and position, were in the range of 1.5-1.7%. Part 2 of this paper set will describe the application of this imaging technique to concrete that contains inclusions.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002075854
|
oai_dc
|
Investigation of influences of mixing parameters on acoustoelastic coefficient of concrete using coda wave interferometry
|
Investigation of influences of mixing parameters on acoustoelastic coefficient of concrete using coda wave interferometry
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Sung Woo Shin(Pukyong National University); Jiyong Lee(Daewoo Engineering & Construction Company); Jeong-Su Kim(Hanwha Research Institute of Technology); Joonwoo Shin(Korea Maritime and Ocean University)"
] |
The stress dependence of ultrasonic wave velocity is known as the acoustoelastic effect. This effect is useful for stress monitoring if the acoustoelastic coefficient of a subject medium is known. The acoustoelastic coefficients of metallic materials such as steel have been studied widely. However, the acoustoelastic coefficient of concrete has not been well understood yet. Basic constituents of concrete are water, cement, and aggregates. The mix proportion of those constituents greatly affects many mechanical and physical properties of concrete and so does the acoustoelastic coefficient of concrete. In this study, influence of the water-cement ratio (w/c ratio) and the fine-coarse aggregates ratio (fa/ta ratio) on the acoustoelastic coefficient of concrete was investigated. The w/c and the fa/ta ratios are important parameters in mix design and affect wave behaviors in concrete. Load-controlled uni-axial compression tests were performed on concrete specimens. Ultrasonic wave measurements were also performed during the compression tests. The stretching coda wave interferometry method was used to obtain the relative velocity change of ultrasonic waves with respect to the stress level of the specimens. From the experimental results, it was found that the w/c ratio greatly affects the acoustoelastic coefficient while the fa/ta ratio does not. The acoustoelastic coefficient increased from 0.003073 MPa-1 to 0.005553 MPa-1 when the w/c ratio was increased from 0.4 to 0.5. On the other hand, the acoustoelastic coefficient changed in small from 0.003606 MPa-1 to 0.003801 MPa-1 when the fa/ta ratio was increased from 0.3 to 0.5. Finally, it was also found that the relative velocity change has a linear relationship with the stress level of concrete.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002075856
|
oai_dc
|
An electromechanical impedance-based method for tensile force estimation and damage diagnosis of post-tensioning systems
|
An electromechanical impedance-based method for tensile force estimation and damage diagnosis of post-tensioning systems
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jiyoung Min(Structural Engineering Research Institute); Hyojin Shim(National Research Foundation of Korea); Chung-Bang Yun(Korea Advanced Institute of Science and Technology); 홍정욱(한국과학기술원)"
] |
We propose an effective methodology using electromechanical impedance characteristics for estimating the remaining tensile force of tendons and simultaneously detecting damages of the anchorage blocks. Once one piezoelectric patch is attached on the anchor head and the other is bonded on the bearing plate, impedance responses are measured through these two patches under varying tensile force conditions. Then statistical indices are calculated from the impedances, and two types of relationship curves between the tensile force and the statistical index (TE Curve) and between statistical indices of two patches (SR Curve) are established. Those are considered as database for monitoring both the tendon and the anchorage system. If damage exists on the bearing plate, the statistical index of patch on the bearing plate would be out of bounds of the SR curve and damage can be detected. A change in the statistical index by damage is calibrated with the SR curve, and the tensile force can be estimated with the corrected index and the TE Curve. For validation of the developed methodology, experimental studies are performed on the scaled model of an anchorage system that is simplified only with 3 solid wedges, a 3-hole anchor head, and a bearing plate. Then, the methodology is applied to a real scale anchorage system that has 19 strands, wedges, an anchor head, a bearing plate, and a steel duct. It is observed that the proposed scheme gives quite accurate estimation of the remaining tensile forces. Therefore, this methodology has great potential for practical use to evaluate the remaining tensile forces and damage status in the post-tensioned structural members.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002075859
|
oai_dc
|
A new methodology development for flood fragility curve derivation considering structural deterioration for bridges
|
A new methodology development for flood fragility curve derivation considering structural deterioration for bridges
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"이재범(Ulsan National Institute of Science and Technology); 이영주(울산과학기술원); 김현준(울산과학기술원); 심성한(울산과학기술원); 김지만(한국건설기술연구원)"
] |
Floods have been known to be one of the main causes of bridge collapse. Contrary to earthquakes, flood events tend to occur repeatedly and more frequently in rainfall areas; flood-induced damage and collapse account for a significant portion of disasters in many countries. Nevertheless, in contrast to extensive research on the seismic fragility analysis for civil infrastructure, relatively little attention has been devoted to the flood-related fragility. The present study proposes a novel methodology for deriving flood fragility curves for bridges. Fragility curves are generally derived by means of structural reliability analysis, and structural failure modes are defined as excessive demands of the displacement ductility of a bridge under increased water pressure resulting from debris accumulation and structural deterioration, which are known to be the primary causes of bridge failures during flood events. Since these bridge failure modes need to be analyzed through sophisticated structural analysis, flood fragility curve derivation that would require repeated finite element analyses may take a long time. To calculate the probability of flood-induced failure of bridges efficiently, in the proposed framework, the first order reliability method (FORM) is employed for reducing the required number of finite element analyses. In addition, two software packages specialized for reliability analysis and finite element analysis, FERUM (Finite Element Reliability Using MATLAB) and ABAQUS, are coupled so that they can exchange their inputs and outputs during structural reliability analysis, and a Python-based interface for FERUM and ABAQUS is newly developed to effectively coordinate the fragility analysis. The proposed framework of flood fragility analysis is applied to an actual reinforced concrete bridge in South Korea to demonstrate the detailed procedure of the approach.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002075858
|
oai_dc
|
Intelligent bolt-jointed system integrating piezoelectric sensors with shape memory alloys
|
Intelligent bolt-jointed system integrating piezoelectric sensors with shape memory alloys
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jong Keun Park(Byuksung College); 박승희(성균관대학교)"
] |
This paper describes a smart structural system, which uses smart materials for real-time monitoring and active control of bolted-joints in steel structures. The goal of this research is to reduce the possibility of failure and the cost of maintenance of steel structures such as bridges, electricity pylons, steel lattice towers and so on. The concept of the smart structural system combines impedance based health monitoring techniques with a shape memory alloy (SMA) washer to restore the tension of the loosened bolt. The impedance-based structural health monitoring (SHM) techniques were used to detect loosened bolts in bolted-joints. By comparing electrical impedance signatures measured from a potentially damage structure with baseline data obtained from the pristine structure, the bolt loosening damage could be detected. An outlier analysis, using generalized extreme value (GEV) distribution, providing optimal decision boundaries, has been carried out for more systematic damage detection. Once the loosening damage was detected in the bolted joint, the external heater, which was bonded to the SMA washer, actuated the washer. Then, the heated SMA washer expanded axially and adjusted the bolt tension to restore the lost torque. Additionally, temperature variation due to the heater was compensated by applying the effective frequency shift (EFS) algorithm to improve the performance of the diagnostic results. An experimental study was conducted by integrating the piezoelectric material based structural health monitoring and the SMA-based active control function on a bolted joint, after which the performance of the smart ‘self-monitoring and self-healing bolted joint system’ was demonstrated.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002075853
|
oai_dc
|
Enhanced impact echo frequency peak by time domain summation of signals with different source receiver spacing
|
Enhanced impact echo frequency peak by time domain summation of signals with different source receiver spacing
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Nils Ryden(Lund University)"
] |
The Impact Echo method can be used to measure the thickness of concrete plate like structures. Measurements are based on the identification of a clear thickness resonance frequency which can be difficult in very thick or highly attenuative plates. In this study the detectability of the measured resonant frequency is enhanced by time domain summation of signals with different source receiver spacing. The proposed method is based on the spatial and temporal properties of the first higher symmetric zero group velocity Lamb mode (S1-ZGV) which are described in detail. No application dependent tuning or filtering is needed which makes the method robust and suitable for implementation in automatic IE thickness measurements. The proposed technique is exemplified with numerical data and field data from a thick concrete wall and a highly attenuative asphalt concrete layer.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957037
|
oai_dc
|
Structural damage identification with power spectral density transmissibility: numerical and experimental studies
|
Structural damage identification with power spectral density transmissibility: numerical and experimental studies
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jun Li(Curtin University); Hong Hao(Curtin University); Juin Voon Lo(The University of Western Australia)"
] |
This paper proposes a structural damage identification approach based on the power spectral density transmissibility (PSDT), which is developed to formulate the relationship between two sets of auto-spectral density functions of output responses. The accuracy of response reconstruction with PSDT is investigated and the damage identification in structures is conducted with measured acceleration responses from the damaged state. Numerical studies on a seven-storey plane frame structure are conducted to investigate the performance of the proposed damage identification approach. The initial finite element model of the structure and measured acceleration measurements from the damaged structure are used for the identification with a dynamic response sensitivity-based model updating method. The simulated damages can be identified accurately without and with a 5% noise effect included in the simulated responses. Experimental studies on a steel plane frame structure in the laboratory are performed to further verify the accuracy of response reconstruction with PSDT and validate the proposed damage identification approach. The locations of the introduced damage are detected accurately and the stiffness reductions in the damaged elements are identified close to the true values. The identification results demonstrated the accuracy of response reconstruction as well as the correctness and efficiency of the proposed damage identification approach.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957039
|
oai_dc
|
A two-stage and two-step algorithm for the identification of structural damage and unknown excitations: numerical and experimental studies
|
A two-stage and two-step algorithm for the identification of structural damage and unknown excitations: numerical and experimental studies
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ying Lei(Xiamen University); Feng Chen(Xiamen University); Huan Zhou(Xiamen University)"
] |
Extended Kalman Filter (EKF) has been widely used for structural identification and damage detection. However, conventional EKF approaches require that external excitations are measured. Also, in the conventional EKF, unknown structural parameters are included as an augmented vector in forming the extended state vector. Hence the sizes of extended state vector and state equation are quite large, which suffers from not only large computational effort but also convergence problem for the identification of a large number of unknown parameters. Moreover, such approaches are not suitable for intelligent structural damage detection due to the limited computational power and storage capacities of smart sensors. In this paper, a two-stage and two-step algorithm is proposed for the identification of structural damage as well as unknown external excitations. In stage-one, structural state vector and unknown structural parameters are recursively estimated in a two-step Kalman estimator approach. Then, the unknown external excitations are estimated sequentially by least-squares estimation in stage-two. Therefore, the number of unknown variables to be estimated in each step is reduced and the identification of structural system and unknown excitation are conducted sequentially, which simplify the identification problem and reduces computational efforts significantly. Both numerical simulation examples and lab experimental tests are used to validate the proposed algorithm for the identification of structural damage as well as unknown excitations for structural health monitoring.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957049
|
oai_dc
|
Structural damage identification based on genetically trained ANNs in beams
|
Structural damage identification based on genetically trained ANNs in beams
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Li Peng-hui(Huazhong University of Science and Technology); Zhu Hong-ping(Huazhong University of Science and Technology); Luo Hui(Huazhong University of Science and Technology); Weng Shun(Huazhong University of Science and Technology)"
] |
This study develops a two stage procedure to identify the structural damage based on the optimized artificial neural networks. Initially, the modal strain energy index (MSEI) is established to extract the damaged elements and to reduce the computational time. Then the genetic algorithm (GA) and artificial neural networks (ANNs) are combined to detect the damage severity. The input of the network is modal strain energy index and the output is the flexural stiffness of the beam elements. The principal component analysis (PCA) is utilized to reduce the input variants of the neural network. By using the genetic algorithm to optimize the parameters, the ANNs can significantly improve the accuracy and convergence of the damage identification. The influence of noise on damage identification results is also studied. The simulation and experiment on beam structures shows that the adaptive parameter selection neural network can identify the damage location and severity of beam structures with high accuracy.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957036
|
oai_dc
|
Damage detection of nonlinear structures with analytical mode decomposition and Hilbert transform
|
Damage detection of nonlinear structures with analytical mode decomposition and Hilbert transform
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Zuo-Cai Wang(Hefei University of Technology); Dong Geng(Hefei University of Technology); Wei-Xin Ren(Hefei University of Technology); Guang-Feng Zhang(Hefei University of Technology); Gen-Da Chen(Missouri University of Science and Technology)"
] |
This paper proposes an analytical mode decomposition (AMD) and Hilbert transform method for structural nonlinearity quantification and damage detection under earthquake loads. The measured structural response is first decomposed into several intrinsic mode functions (IMF) using the proposed AMD method. Each IMF is an amplitude modulated-frequency modulated signal with narrow frequency bandwidth. Then, the instantaneous frequencies of the decomposed IMF can be defined with Hilbert transform. However, for a nonlinear structure, the defined instantaneous frequencies from the decomposed IMF are not equal to the instantaneous frequencies of the structure itself. The theoretical derivation in this paper indicates that the instantaneous frequency of the decomposed measured response includes a slowly-varying part which represents the instantaneous frequency of the structure and rapidly-varying part for a nonlinear structure subjected to earthquake excitations. To eliminate the rapidly-varying part effects, the instantaneous frequency is integrated over time duration. Then the degree of nonlinearity index, which represents the damage severity of structure, is defined based on the integrated instantaneous frequency in this paper. A one-story hysteretic nonlinear structure with various earthquake excitations are simulated as numerical examples and the degree of nonlinearity index is obtained. Finally, the degree of nonlinearity index is estimated from the experimental data of a seven-story building under four earthquake excitations. The index values for the building subjected to a low intensity earthquake excitation, two medium intensity earthquake excitations, and a large intensity earthquake excitation are calculated as 12.8%, 23.0%, 23.2%, and 39.5%, respectively.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957043
|
oai_dc
|
An exploratory study of stress wave communication in concrete structures
|
An exploratory study of stress wave communication in concrete structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Gangbing Song(University of Houston); Qing Ji(University of Houston); Michael Ho(University of Houston); Rong Zheng(McMaster University); Zhi Ding(University of California)"
] |
Large concrete structures are prone to cracks and damages over time from human usage, weathers, and other environmental attacks such as flood, earthquakes, and hurricanes. The health of the concrete structures should be monitored regularly to ensure safety. A reliable method of real time communications can facilitate more frequent structural health monitoring (SHM) updates from hard to reach positions, enabling crack detections of embedded concrete structures as they occur to avoid catastrophic failures. By implementing an unconventional mode of communication that utilizes guided stress waves traveling along the concrete structure itself, we may be able to free structural health monitoring from costly (re-)installation of communication wires. In stress-wave communications, piezoelectric transducers can act as actuators and sensors to send and receive modulated signals carrying concrete status information. The new generation of lead zirconate titanate (PZT) based smart aggregates cause multipath propagation in the homogeneous concrete channel, which presents both an opportunity and a challenge for multiple sensors communication. We propose a time reversal based pulse position modulation (TR-PPM) communication for stress wave communication within the concrete structure to combat multipath channel dispersion. Experimental results demonstrate successful transmission and recovery of TR-PPM using stress waves. Compared with PPM, we can achieve higher data rate and longer link distance via TR-PPM. Furthermore, TR-PPM remains effective under low signal-to-noise (SNR) ratio. This work also lays the foundation for implementing multiple-input multiple-output (MIMO) stress wave communication networks in concrete channels
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957044
|
oai_dc
|
Instrumentation on structural health monitoring systems to real world structures
|
Instrumentation on structural health monitoring systems to real world structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jun Teng(Fujian University of technology); Wei Lu(Harbin Institute of Technology); Runfa Wen(Harbin Institute of Technology); Ting Zhang(Harbin Institute of Technology)"
] |
Instrumentation on structural health monitoring system imposes critical issues for applying the structural monitoring system to real world structures, for which not only on the configuration and geometry, but also aesthetics on the system to be monitored should be considered. To illustrate this point, two real world structural health monitoring systems, the structural health monitoring system of Shenzhen Vanke Center and the structural health monitoring system of Shenzhen Bay Stadium in China, are presented in the paper. The instrumentation on structural health monitoring systems of real world structures is addressed by providing the description of the structure, the purpose of the structural health monitoring system implementation, as well as details of the system integration including the installations on the sensors and acquisition equipment and so on. In addition, an intelligent algorithm on stress identification using measurements from multi-region is presented in the paper. The stress identification method is deployed using the fuzzy pattern recognition and Dempster-Shafer evidence theory, where the measurements of limited strain sensors arranged on structure are the input data of the method. As results, at the critical parts of the structure, the stress distribution evaluated from the measurements has shown close correlation to the numerical simulation results on the steel roof of the Beijing National Aquatics Center in China. The research work in this paper can provide a reference for the design and implementation of both real world structural health monitoring systems and intelligent algorithm to identify stress distribution effectively.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957045
|
oai_dc
|
Substructural parameters and dynamic loading identification with limited observations
|
Substructural parameters and dynamic loading identification with limited observations
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Bin Xu(Hunan University); Jia He(Hunan University)"
] |
Convergence difficulty and available complete measurement information have been considered as two primary challenges for the identification of large-scale engineering structures. In this paper, a time domain substructural identification approach by combining a weighted adaptive iteration (WAI) algorithm and an extended Kalman filter method with a weighted global iteration (EFK-WGI) algorithm was proposed for simultaneous identification of physical parameters of concerned substructures and unknown external excitations applied on it with limited response measurements. In the proposed approach, according to the location of the unknown dynamic loadings and the partially available structural response measurements, part of structural parameters of the concerned substructure and the unknown loadings were first identified with the WAI approach. The remaining physical parameters of the concerned substructure were then determined by EFK-WGI basing on the previously identified loadings and substructural parameters. The efficiency and accuracy of the proposed approach was demonstrated via a 20-story shear building structure and 23 degrees of freedom (DOFs) planar truss model with unknown external excitation and limited observations. Results show that the proposed approach is capable of satisfactorily identifying both the substructural parameters and unknown loading within limited iterations when both the excitation and dynamic response are partially unknown.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957042
|
oai_dc
|
Structural time-varying damage detection using synchrosqueezing wavelet transform
|
Structural time-varying damage detection using synchrosqueezing wavelet transform
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jing-Liang Liu(Central South University); Zuo-Cai Wang(Hefei University of Technology); Wei-Xin Ren(Central South University); Xing-Xin Li(Hefei University of Technology)"
] |
This paper proposed a structural time-varying damage detection method by using synchrosqueezing wavelet transform. The instantaneous frequencies of a structure with time-varying damage are first extracted using the synchrosqueezing wavelet transform. Since the proposed synchrosqueezing wavelet transform is invertible, thus each individual component can be reconstructed and the modal participation factor ratio can be extracted based on the amplitude of the analytical signals of the reconstructed individual components. Then, the new time-varying damage index is defined based on the extracted instantaneous frequencies and modal participation factor ratio. Both free and forced vibrations of a classical Duffing nonlinear system and a simply supported beam structure with abrupt and linear time-varying damage are simulated. The proposed synchrosqueezing wavelet transform method can successfully extract the instantaneous frequencies of the damaged structures under free vibration or vibration due to earthquake excitation. The results also show that the defined time-varying damage index can effectively track structural time-varying damage.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957047
|
oai_dc
|
Practical issues in signal processing for structural flexibility identification
|
Practical issues in signal processing for structural flexibility identification
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"J. Zhang(Southeast University); Y. Zhou(Hunan University); P.J. Li(Southeast University)"
] |
Compared to ambient vibration testing, impact testing has the merit to extract not only structural modal parameters but also structural flexibility. Therefore, structural deflections under any static load can be predicted from the identified results of the impact test data. In this article, a signal processing procedure for structural flexibility identification is first presented. Especially, practical issues in applying the proposed procedure for structural flexibility identification are investigated, which include sensitivity analyses of three pre-defined parameters required in the data pre-processing stage to investigate how they affect the accuracy of the identified structural flexibility. Finally, multiple-reference impact test data of a three-span reinforced concrete T-beam bridge are simulated by the FE analysis, and they are used as a benchmark structure to investigate the practical issues in the proposed signal processing procedure for structural flexibility identification.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957041
|
oai_dc
|
Structural health rating (SHR)-oriented 3D multi-scale finite element modeling and analysis of Stonecutters Bridge
|
Structural health rating (SHR)-oriented 3D multi-scale finite element modeling and analysis of Stonecutters Bridge
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Y.Q. Ni(The Hong Kong Polytechnic University); X.F. Li(The Hong Kong Polytechnic University); K.Y. Wong(The Hong Kong Special Administrative Region); K.W.Y. Chan(The Hong Kong Special Administrative Region)"
] |
The Stonecutters Bridge (SCB) in Hong Kong is the third-longest cable-stayed bridge in the world with a main span stretching 1,018 m between two 298 m high single-leg tapering composite towers. A Wind and Structural Health Monitoring System (WASHMS) is being implemented on SCB by the Highways Department of The Hong Kong SAR Government, and the SCB-WASHMS is composed of more than 1,300 sensors in 15 types. In order to establish a linkage between structural health monitoring and maintenance management, a Structural Health Rating System (SHRS) with relevant rating tools and indices is devised. On the basis of a 3D space frame finite element model (FEM) of SCB and model updating, this paper presents the development of an SHR-oriented 3D multi-scale FEM for the purpose of load-resistance analysis and damage evaluation in structural element level, including modeling, refinement and validation of the multi-scale FEM. The refined 3D structural segments at deck and towers are established in critical segment positions corresponding to maximum cable forces. The components in the critical segment region are modeled as a full 3D FEM and fitted into the 3D space frame FEM. The boundary conditions between beam and shell elements are performed conforming to equivalent stiffness, effective mass and compatibility of deformation. The 3D multi-scale FEM is verified by the in-situ measured dynamic characteristics and static response. A good agreement between the FEM and measurement results indicates that the 3D multi-scale FEM is precise and efficient for WASHMS and SHRS of SCB. In addition, stress distribution and concentration of the critical segments in the 3D multi-scale FEM under temperature loads, static wind loads and equivalent seismic loads are investigated. Stress concentration elements under equivalent seismic loads exist in the anchor zone in steel/concrete beam and the anchor plate edge in steel anchor box of the towers.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957040
|
oai_dc
|
Blind modal identification of output-only non-proportionally-damped structures by time-frequency complex independent component analysis
|
Blind modal identification of output-only non-proportionally-damped structures by time-frequency complex independent component analysis
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Satish Nagarajaiah(Rice Univ.); Yongchao Yang(Rice Univ.)"
] |
Recently, a new output-only modal identification method based on time-frequency independent component analysis (ICA) has been developed by the authors and shown to be useful for even highly-damped structures. In many cases, it is of interest to identify the complex modes of structures with non-proportional damping. This study extends the time-frequency ICA based method to a complex ICA formulation for output-only modal identification of non-proportionally-damped structures. The connection is established between complex ICA model and the complex-valued modal expansion with sparse time-frequency representation, thereby blindly separating the measured structural responses into the complex mode matrix and complex-valued modal responses. Numerical simulation on a non-proportionally-damped system, laboratory experiment on a highly-damped three-story frame, and a real-world highly-damped base-isolated structure identification example demonstrate the capability of the time-frequency complex ICA method for identification of structures with complex modes in a straightforward and efficient manner.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957046
|
oai_dc
|
Sensor placement optimization in structural health monitoring using distributed monkey algorithm
|
Sensor placement optimization in structural health monitoring using distributed monkey algorithm
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ting-Hua Yi(Dalian University of Technology); Hong-Nan Li(Dalian University of Technology); Xu-Dong Zhang(Dalian University of Technology)"
] |
Proper placement of sensors plays a key role in construction and implementation of an effective structural health monitoring (SHM) system. This paper proposes a novel methodology called the distributed monkey algorithm (DMA) for the optimum design of SHM system sensor arrays. Different from the existing algorithms, the dual-structure coding method is adopted for the representation of design variables and the single large population is partitioned into subsets and each subpopulation searches the space in different directions separately, leading to quicker convergence and higher searching capability. After the personal areas of all subpopulations have been finished, the initial optimal solutions in every subpopulation are extracted and reordered into a new subpopulation, and the harmony search algorithm (HSA) is incorporated to find the final optimal solution. A computational case of a high-rise building has been implemented to demonstrate the effectiveness of the proposed method. Investigations have clearly suggested that the proposed DMA is simple in concept, few in parameters, easy in implementation, and could generate sensor configurations superior to other conventional algorithms both in terms of generating optimal solutions as well as faster convergence.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001957038
|
oai_dc
|
Laser based impedance measurement for pipe corrosion and bolt-loosening detection
|
Laser based impedance measurement for pipe corrosion and bolt-loosening detection
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"손훈(Korea Advanced Institute for Science and Technolog); Jinyeol Yang(Korea Advanced Institute for Science and Technolog); Peipei Liu(Korea Advanced Institute for Science and Technolog); Suyoung Yang(Korea Advanced Institute for Science and Technolog); Hyeonseok Lee(Korea Advanced Institute for Science and Technolog)"
] |
This study proposes a laser based impedance measurement system and impedance based pipe corrosion and bolt-loosening monitoring techniques under temperature variations. For impedance measurement, the laser based impedance measurement system is optimized and adopted in this paper. First, a modulated laser beam is radiated to a photodiode, converting the laser beam into an electric signal. Then, the electric signal is applied to a MFC transducer attached on a target structure for ultrasonic excitation. The corresponding impedance signals are measured, re-converted into a laser beam, and radiated back to the other photodiode located in a data interrogator. The transmitted impedance signals are treated with an outlier analysis using generalized extreme value (GEV) statistics to reliably signal off structural damage. Validation of the proposed technique is carried out to detect corrosion and bolt-loosening in lab-scale carbon steel elbow pipes under varying temperatures. It has been demonstrated that the proposed technique has a potential to be used for structural health monitoring (SHM) of pipe structures.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002048875
|
oai_dc
|
Unified solutions for piezoelectric bilayer cantilevers and solution modifications
|
Unified solutions for piezoelectric bilayer cantilevers and solution modifications
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Zhifei Shi(Beijing Jiaotong University); Xianfeng Wang(Beijing Jiaotong University)"
] |
Based on the theory of piezoelasticity, the static performance of a piezoelectric bilayer cantilever fully covered with electrodes on the upper and lower surfaces is studied. Three models are considered, i.e., the sensor model, the driving displacement model and the blocking force model. By establishing suitable boundary conditions and proposing an appropriate Airy stress function, the exact solutions for piezoelectric bilayer cantilevers are obtained, and the effect of ambient thermal excitation is taken into account. Since the layer thicknesses and material parameters are distinguished in different layers, this paper gives unified solutions for composite piezoelectric bilayer cantilevers including piezoelectric bimorph and piezoelectric heterogeneous bimorph, etc. For some special cases, the simplifications of the present results are compared with other solutions given by other researches based on one-dimensional constitutive equations, and some amendments have been found. The present investigation shows: (1) for a PZT-4 piezoelectric bimorph, the amendments of tip deflections induced by an end shear force, an end moment or an external voltage are about 19.59%, 23.72% and 7.21%, respectively; (2) for a PZT-4-Al piezoelectric heterogeneous bimorph with constant layer thicknesses, the amendments of tip deflections induced by an end shear force, an end moment or an external voltage are 9.85%, 11.78% and 4.07%, respectively, and the amendments of the electrode charges induced by an end shear force or an end moment are both 1.04%; (3) for a PZT-4-Al piezoelectric heterogeneous bimorph with different layer thicknesses, the maximum amendment of tip deflection approaches 23.72%, and the maximum amendment of electrode charge approaches 31.09%. The present solutions can be used to optimize bilayer devices, and the Airy stress function can be used to study other piezoelectric cantilevers including multi-layered piezoelectric cantilevers under corresponding loads.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002048880
|
oai_dc
|
Quasi real-time post-earthquake damage assessment of lifeline systems based on available intensity measure maps
|
Quasi real-time post-earthquake damage assessment of lifeline systems based on available intensity measure maps
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Marco Torbol(울산과학기술원)"
] |
In civil engineering, probabilistic seismic risk assessment is used to predict the economic damage to a lifeline system of possible future earthquakes. The results are used to plan mitigation measures and to strengthen the structures where necessary. Instead, after an earthquake public authorities need mathematical models that compute: the damage caused by the earthquake to the individual vulnerable components and links, and the global behavior of the lifeline system. In this study, a framework that was developed and used for prediction purpose is modified to assess the consequences of an earthquake in quasi real-time after such earthquake happened. This is possible because nowadays entire seismic regions are instrumented with tight networks of strong motion stations, which provide and broadcast accurate intensity measure maps of the event to the public within minutes. The framework uses the broadcasted map and calculates the damage to the lifeline system and its component in quasi real-time. The results give the authorities the most likely status of the system. This helps emergency personnel to deal with the damage and to prioritize visual inspections and repairs. A highway transportation network is used as a test bed but any lifeline system can be analyzed.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002048884
|
oai_dc
|
Magnetorheological fluids subjected to tension, compression, and oscillatory squeeze input
|
Magnetorheological fluids subjected to tension, compression, and oscillatory squeeze input
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ali K. El Wahed(University of Dundee); Loaie B. Balkhoyor(University of Dundee)"
] |
Magnetorheological (MR) fluids are capable of changing their rheological properties under the application of external fields. When MR fluids operate in the so-called squeeze mode, in which displacement levels are limited to a few millimetres but there are large forces, they have many potential applications in vibration isolation. This paper presents an experimental and a numerical investigation of the performance of an MR fluid under tensile and compressive loads and oscillatory squeeze-flow. The performance of the fluid was found to depend dramatically on the strain direction. The shape of the stress-strain hysteresis loops was affected by the strength of the applied field, particularly when the fluid was under tensile loading. In addition, the yield force of the fluid under the oscillatory squeeze-flow mode changed almost linearly with the applied electric or magnetic field. Finally, in order to shed further light on the mechanism of the MR fluid under squeeze operation, computational fluid dynamics analyses of non-Newtonian fluid behaviour using the Bingham-plastic model were carried out. The results confirmed superior fluid performance under compressive inputs.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002048877
|
oai_dc
|
Semi-active control of seismic response of a building using MR fluid-based tuned mass damper
|
Semi-active control of seismic response of a building using MR fluid-based tuned mass damper
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ashutosh Bagchi(Concordia University); Kambiz Esteki(Concordia University); Ramin Sedaghati(Concordia University)"
] |
While tuned mass dampers are found to be effective in suppressing vibration in a tall building, integrating it with a semi-active control system enables it to perform more efficiently. In this paper a forty-story tall steel-frame building designed according to the Canadian standard, has been studied with and without semi-active and passive tuned mass dampers. The building is assumed to be located in the Vancouver, Canada. A magneto-rheological fluid based semi-active tuned mass damper has been optimally designed to suppress the vibration of the structure against seismic excitation, and an appropriate control procedure has been implemented to optimize the building\'s semi-active tuned mass system to reduce the seismic response. Furthermore, the control system parameters have been adjusted to yield the maximum reduction in the structural displacements at different floor levels. The response of the structure has been studied with a variety of ground motions with low, medium and high frequency contents to investigate the performance of the semi-active tuned mass damper in comparison to that of a passive tuned mass damper. It has been shown that the semi-active control system modifies structural response more effectively than the classic passive tuned mass damper in both mitigation of maximum displacement and reduction of the settling time of the building.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002048882
|
oai_dc
|
EMD-based output-only identification of mode shapes of linear structures
|
EMD-based output-only identification of mode shapes of linear structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Omid Bahar(International Institute of Earthquake Engineering and Seismology); Soheil Ramezani(International Institute of Earthquake Engineering and Seismology)"
] |
The Hilbert-Huang transform (HHT) consists of empirical mode decomposition (EMD) and Hilbert spectral analysis. EMD has been successfully applied for identification of mode shapes of structures based on input-output approaches. This paper aims to extend application of EMD for output-only identification of mode shapes of linear structures. In this regard, a new simple and efficient method based on band-pass filtering and EMD is proposed. Having rather accurate estimates of modal frequencies from measured responses, the proposed method is capable to extract the corresponding mode shapes. In order to evaluate the accuracy and performance of the proposed identification method, two case studies are considered. In the first case, the performance of the method is validated through the analysis of simulated responses obtained from an analytical structural model with known dynamical properties. The low-amplitude responses recorded from the UCLA Factor Building during the 2004 Parkfield earthquake are used in the second case to identify the first three mode shapes of the building in three different directions. The results demonstrate the remarkable ability of the proposed method in correct estimation of mode shapes of the linear structures based on rather accurate modal frequencies.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002048879
|
oai_dc
|
Large amplitude free vibration analysis of laminated composite spherical shells embedded with piezoelectric layers
|
Large amplitude free vibration analysis of laminated composite spherical shells embedded with piezoelectric layers
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Subrata K. Panda(National Institute of Technology); Vijay K. Singh(National Institute of Technology)"
] |
Numerical analysis of large amplitude free vibration behaviour of laminated composite spherical shell panel embedded with the piezoelectric layer is presented in this article. For the investigation purpose, a general nonlinear mathematical model has been developed using higher order shear deformation mid-plane kinematics and Green-Lagrange nonlinearity. In addition, all the nonlinear higher order terms are included in the present mathematical model to achieve any general case. The nonlinear governing equation of freely vibrated shell panel is obtained using Hamilton\'s principle and discretised using isoparametric finite element steps. The desired nonlinear solutions are computed numerically through a direct iterative method. The validity of present nonlinear model has been checked by comparing the responses to those available published literature. In order to examine the efficacy and applicability of the present developed model, few numerical examples are solved for different geometrical parameters (fibre orientation, thickness ratio, aspect ratio, curvature ratio, support conditions and amplitude ratio) with and/or without piezo embedded layers and discussed in details.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002048883
|
oai_dc
|
Extracting parameters of TMD and primary structure from the combined system responses
|
Extracting parameters of TMD and primary structure from the combined system responses
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chi-Chang Lin(National Chung Hsing University); Jer-Fu Wang(National Museum of Natural Science)"
] |
Tuned mass dampers (TMDs) have been a prevalent vibration control device for suppressing excessive vibration because of environmental loadings in contemporary tall buildings since the mid-1970s. A TMD must be tuned to the natural frequency of the primary structure to be effective. In practice, a TMD may be assembled in situ, simultaneously with the building construction. In such a situation, the respective dynamic properties of the TMD device and building cannot be identified to determine the tuning status of the TMD. For this purpose, a methodology was developed to obtain the parameters of the TMD and primary building on the basis of the eigenparameters of any two complex modes of the combined building–TMD system. The theory was derived in state-space to characterize the nonclassical damping feature of the system, and combined with a system identification technique to obtain the system eigenparameters using the acceleration measurements. The proposed procedure was first demonstrated using a numerical verification and then applied to real, experimental data of a large-scale building–TMD system. The results showed that the procedure is capable of identifying the respective parameters of the TMD and primary structure and is applicable in real implementations by using only the acceleration response measurements of the TMD and its located floor.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002048881
|
oai_dc
|
A comprehensive analysis on the discretization method of the equation of motion in piezoelectrically actuated microbeams
|
A comprehensive analysis on the discretization method of the equation of motion in piezoelectrically actuated microbeams
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"M. Zamanian(Kharazmi University); H. Rezaei(Kharazmi University); M. Hadilu(Kharazmi University); S.A.A. Hosseini(Kharazmi University)"
] |
In many of microdevices a part of a microbeam is covered by a piezoelectric layer. Depend on the application a DC or AC voltage is applied between upper and lower side of the piezoelectric layer. A common method in many of previous works for evaluating the response of these structures is discretizing by Galerkin method. In these works often single mode shape of a uniform microbeam i.e. the microbeam without piezoelectric layer has been used as comparison function, and so the convergence of the solution has not been verified. In this paper the Galerkin method is used for discretization, and a comprehensive analysis on the convergence of solution of equation that is discretized using this comparison function is studied for both clamped-clamped and clamped-free microbeams. The static and dynamic solution resulted from Galerkin method is compared to the modal expansion solution. In addition the static solution is compared to an exact solution. It is denoted that the required numbers of uniform microbeam mode shapes for convergence of static solution due to DC voltage depends on the position and thickness of deposited piezoelectric layer. It is shown that when the clamped-clamped microbeam is coated symmetrically by piezoelectric layer, then the convergence for static solution may be obtained using only first mode. This result is valid for clamped –free case when it is covered by piezoelectric layer from left clamped side to the right. It is shown that when voltage is AC then the number of required uniform microbeam shape mode for convergence is much more than the number of required mode in modal expansion due to the dynamic effect of piezoelectric layer. This difference increases by increasing the piezoelectric thickness, the closeness of the excitation frequency to natural frequency and decreasing the damping coefficient. This condition is often indefeasible in microresonator system. It is concluded that discreitizing the equation of motion using one mode shape of uniform microbeam as comparison function in many of previous works causes considerable errors.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002048876
|
oai_dc
|
Coupled electro-elastic analysis of functionally graded piezoelectric material plates
|
Coupled electro-elastic analysis of functionally graded piezoelectric material plates
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chih-Ping Wu(National Cheng Kung University); Shuang Ding(National Cheng Kung University)"
] |
A unified formulation of finite layer methods (FLMs), based on the Reissner mixed variational theorem (RMVT), is developed for the three-dimensional (3D) coupled electro-elastic analysis of simply-supported, functionally graded piezoelectric material (FGPM) plates with open- and closed-circuit surface conditions and under electro-mechanical loads. In this formulation, the material properties of the plate are assumed to obey an exponent-law varying exponentially through the thickness coordinate, and the plate is divided into a number of finite rectangular layers, in which the trigonometric functions and Lagrange polynomials are used to interpolate the in- and out-of-plane variations of the primary field variables of each individual layer, respectively, such as the elastic displacement, transverse shear and normal stress, electric potential, and normal electric displacement components. The relevant orders used for expanding these variables in the thickness coordinate can be freely chosen as the linear, quadratic and cubic orders. Four different mechanical/electrical loading conditions applied on the top and bottom surfaces of the plate are considered, and the corresponding coupled electro-elastic analysis of the loaded FGPM plates is undertaken. The accuracy and convergence rate of the RMVT-based FLMs are assessed by comparing their solutions with the exact 3D piezoelectricity ones available in the literature.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART002048878
|
oai_dc
|
Assessment of temperature effect in structural health monitoring with piezoelectric wafer active sensors
|
Assessment of temperature effect in structural health monitoring with piezoelectric wafer active sensors
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Tuncay Kamas(Eskisehir Osmangazi University); Banibrata Poddar(University of South Carolina); Bin Lin(University of South Carolina); Lingyu Yu(University of South Carolina)"
] |
This paper presents theoretical and experimental evaluation of the structural health monitoring (SHM) capability of piezoelectric wafer active sensors (PWAS) at elevated temperatures. This is important because the technologies for structural sensing and monitoring need to account for the thermal effect and compensate for it. Permanently installed PWAS transducers have been One of the extensively employed sensor technologies for in-situ continuous SHM. In this paper, the electro-mechanical impedance spectroscopy (EMIS) method has been utilized as a dynamic descriptor of PWAS behavior and as a high frequency standing wave local modal technique. Another SHM technology utilizes PWAS as far-field transient transducers to excite and detect guided waves propagating through the structure. This paper first presents how the EMIS method is used to qualify and quantify circular PWAS resonators in an increasing temperature environment up to 230 deg C. The piezoelectric material degradation with temperature was investigated and trends of variation with temperature were deduced from experimental measurements. These effects were introduced in a wave propagation simulation software called Wave Form Revealer (WFR). The thermal effects on the substrate material were also considered. Thus, the changes in the propagating guided wave signal at various temperatures could be simulated. The paper ends with summary and conclusions followed by suggestions for further work.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001902244
|
oai_dc
|
The application of a fuzzy inference system and analytical hierarchy process based online evaluation framework to the Donghai Bridge Health Monitoring System
|
The application of a fuzzy inference system and analytical hierarchy process based online evaluation framework to the Donghai Bridge Health Monitoring System
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Danhui Dan(Tongji University); Limin Sun(Tongji University); Zhifang Yang(Shanghai Municipal Engineering Research Institute); Daqi Xie(Donghai Bridge Management Ltd.)"
] |
In this paper, a fuzzy inference system and an analytical hierarchy process-based online evaluation technique is developed to monitor the condition of the 32-km Donghai Bridge in Shanghai. The system has 478 sensors distributed along eight segments selected from the whole bridge. An online evaluation subsystem is realized, which uses raw data and extracted features or indices to give a set of hierarchically organized condition evaluations. The thresholds of each index were set to an initial value obtained from a structure damage and performance evolution analysis of the bridge. After one year of baseline monitoring, the initial threshold system was updated from the collected data. The results show that the techniques described are valid and reliable. The online method fulfills long-term infrastructure health monitoring requirements for the Donghai Bridge.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001902248
|
oai_dc
|
SVR model reconstruction for the reliability of FBG sensor network based on the CFRP impact monitoring
|
SVR model reconstruction for the reliability of FBG sensor network based on the CFRP impact monitoring
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Xiao Li Zhang(Pukyong National University); Dakai Liang(Nanjing University of Aeronautics and Astronautics); Jiyun Lu(Nanjing University of Aeronautics and Astronautics); Jie Zeng(Nanjing University of Aeronautics and Astronautics)"
] |
The objective of this study is to improve the survivability and reliability of the FBG sensor network in the structural health monitoring (SHM) system. Therefore, a model reconstruction soft computing recognition algorithm based on support vector regression (SVR) is proposed to achieve the high reliability of the FBG sensor network, and the grid search algorithm is used to optimize the parameters of SVR model. Furthermore, in order to demonstrate the effectiveness of the proposed model reconstruction algorithm, a SHM system based on an eight-point fiber Bragg grating (FBG) sensor network is designed to monitor the foreign-object low velocity impact of a CFRP composite plate. Simultaneously, some sensors data are neglected to simulate different kinds of FBG sensor network failure modes, the predicting results are compared with non-reconstruction for the same failure mode. The comparative results indicate that the performance of the model reconstruction recognition algorithm based on SVR has more excellence than that of non-reconstruction, and the model reconstruction algorithm almost keeps the consistent predicting accuracy when no sensor, one sensor and two sensors are invalid in the FBG sensor network, thus the reliability is improved when there are FBG sensors are invalid in the structural health monitoring system
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001902255
|
oai_dc
|
Comprehensive piezo-thermo-elastic analysis of a thick hollow spherical shell
|
Comprehensive piezo-thermo-elastic analysis of a thick hollow spherical shell
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"M. Arefi(University of Kashan); M.J. Khoshgoftar(Tarbiat Modares University)"
] |
The present paper develops piezo-thermo-elastic analysis of a thick spherical shell for generalized functionally graded piezoelectric material. The assumed structure is loaded under thermal, electrical and mechanical loads. The mechanical, thermal and electrical properties are graded along the radial direction based on a power function with three different non homogenous indexes. Primarily, the non homogenous heat transfer equation is solved by applying the general boundary conditions, individually. Substitution of stress, strain, electrical displacement and material properties in equilibrium and Maxwell equations present two non homogenous differential equation of order two. The main objective of the present study is to improve the relations between mechanical and electrical loads in hollow spherical shells especially for functionally graded piezoelectric materials. The obtained results can evaluate the effect of every non homogenous parameter on the mechanical and electrical components.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001902252
|
oai_dc
|
Localized reliability analysis on a large-span rigid frame bridge based on monitored strains from the long-term SHM system
|
Localized reliability analysis on a large-span rigid frame bridge based on monitored strains from the long-term SHM system
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Zejia Liu(South China University of Technology); Liqun Tang(South China University of Technology); Yinghua Li(South China University of Technology); Yiping Liu(South China University of Technology); Zhenyu Jiang(South China University of Technology); Daining Fang(South China University of Technology)"
] |
With more and more built long-term structural health monitoring (SHM) systems, it has been considered to apply monitored data to learn the reliability of bridges. In this paper, based on a long-term SHM system, especially in which the sensors were embedded from the beginning of the construction of the bridge, a method to calculate the localized reliability around an embedded sensor is recommended and implemented. In the reliability analysis, the probability distribution of loading can be the statistics of stress transferred from the monitored strain which covered the effects of both the live and dead loads directly, and it means that the mean value and deviation of loads are fully derived from the monitored data. The probability distribution of resistance may be the statistics of strength of the material of the bridge accordingly. With five years\' monitored strains, the localized reliabilities around the monitoring sensors of a bridge were computed by the method. Further, the monitored stresses are classified into two time segments in one year period to count the loading probability distribution according to the local climate conditions, which helps us to learn the reliability in different time segments and their evolvement trends. The results show that reliabilities and their evolvement trends in different parts of the bridge are different though they are all reliable yet. The method recommended in this paper is feasible to learn the localized reliabilities revealed from monitored data of a long-term SHM system of bridges, which would help bridge engineers and managers to decide a bridge inspection or maintenance strategy
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001902237
|
oai_dc
|
Effects of photostrictive actuator and active control of flexible membrane structure
|
Effects of photostrictive actuator and active control of flexible membrane structure
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"S.C. Gajbhiye(Saguja Univeristy); S. H. UPADHYAY(Indian Institute of Technology Roorkee); S.P. Harsha(Indian Institute of Technology Roorkee)"
] |
The purpose of this paper is to investigate the flexible structure of parabolic shell using photostrictive actuators. The analysis is made to know its dynamic behavior and light-induced control forces for coupled parabolic shell. The effects of an actuator location as well as membrane and bending components under the control action have been analyzed considering the approximate spherical model. The parabolic membrane shell accuracy is being mathematically approximated and validated comparing the light induced control forces using approximate equivalent spherical shell model. The parabolic shell with kapton smart material and photostrictive actuators has been used to formulate the governing equation in the transverse direction. The Kirchhoff-Love assumptions are used to obtain the governing equation of shell with actuator. The mechanical membrane forces and bending moments for parabolic thin shell with actuator is used to analyze the dynamic effect. The results show that membrane control action is much more significant than bending control action. Photostrictive actuators oriented along circumferential direction (actuator-2) can give better control effect than actuators placed along longitudinal direction (actuator-1). The slight difference is observed between spherical and parabolic shell for a surface with focal length to the diameter ratio of 1.00 or more than unity. Space applications often have the shape of parabolical shells or shell of revolution, due to their required focusing, aiming, or reflecting performance. The present approach is focused that photostrictive actuators can effectively control the vibration of parabolical membrane shell. Also, the actuator\'s location plays an important role in defining the control force.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001902240
|
oai_dc
|
Statistics based localized damage detection using vibration response
|
Statistics based localized damage detection using vibration response
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Siavash Dorvash(Lehigh University); Shamim N. Pakzad(Lehigh University); Elizabeth L. LaCrosse(Lehigh University)"
] |
Damage detection is a challenging, complex, and at the same time very important research topic in civil engineering. Identifying the location and severity of damage in a structure, as well as the global effects of local damage on the performance of the structure are fundamental elements of damage detection algorithms. Local damage detection is essential for structural health monitoring since local damages can propagate and become detrimental to the functionality of the entire structure. Existing studies present several methods which utilize sensor data, and track global changes in the structure. The challenging issue for these methods is to be sensitive enough in identifying local damage. Autoregressive models with exogenous terms (ARX) are a popular class of modeling approaches which are the basis for a large group of local damage detection algorithms. This study presents an algorithm, called Influence-based Damage Detection Algorithm (IDDA), which is developed for identification of local damage based on regression of the vibration responses. The formulation of the algorithm and the post-processing statistical framework is presented and its performance is validated through implementation on an experimental beam-column connection which is instrumented by dense-clustered wired and wireless sensor networks. While implementing the algorithm, two different sensor networks with different sensing qualities are utilized and the results are compared. Based on the comparison of the results, the effect of sensor noise on the performance of the proposed algorithm is observed and discussed in this paper.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001902243
|
oai_dc
|
Stochastic DLV method for steel truss structures: simulation and experiment
|
Stochastic DLV method for steel truss structures: simulation and experiment
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Yonghui An(Dalian University of technology); Jinping Ou(Dalian University of technology); Jian Li(University of Kansas); B.F. Spencer Jr(University of Illinois at Urbana-Champaign)"
] |
The stochastic damage locating vector (SDLV) method has been studied extensively in recent years because of its potential to determine the location of damage in structures without the need for measuring the input excitation. The SDLV method has been shown to be a particularly useful tool for damage localization in steel truss bridges through numerical simulation and experimental validation. However, several issues still need clarification. For example, two methods have been suggested for determining the observation matrix C identified for the structural system; yet little guidance has been provided regarding the conditions under which the respective formulations should be used. Additionally, the specific layout of the sensors to achieve effective performance with the SDLV method and the associated relationship to the specific type of truss structure have yet to be explored. Moreover, how the location of truss members influences the damage localization results should be studied. In this paper, these three issues are first investigated through numerical simulation and subsequently the main results are validated experimentally. The results of this paper provide guidance on the effective use of the SDLV method.
|
토목공학
| null |
kci_detailed_000088.xml
|
|||
ART001902250
|
oai_dc
|
Recovering structural displacements and velocities from acceleration measurements
|
Recovering structural displacements and velocities from acceleration measurements
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"T.W. Ma(University of Hawaii); M. Bell(University of Hawaii); N.S. Xu(University of Hawaii); W. Lu(University of Hawaii)"
] |
In this research, an internal model based method is proposed to estimate the structural displacements and velocities under ambient excitation using only acceleration measurements. The structural response is assumed to be within the linear range. The excitation is assumed to be with zero mean and relatively broad bandwidth such that at least one of the fundamental modes of the structure is excited and dominates in the response. Using the structural modal parameters and partial knowledge of the bandwidth of the excitation, the internal models of the structure and the excitation can be respectively established, which can be used to form an autonomous state-space representation of the system. It is shown that structural displacements, velocities, and accelerations are the states of such a system, and it is fully observable when the measured output contains structural accelerations only. Reliable estimates of structural displacements and velocities are obtained using the standard Kalman filtering technique. The effectiveness and robustness of the proposed method has been demonstrated and evaluated via numerical simulations on an eight-story lumped mass model and experimental data of a three-story frame excited by the ground accelerations of actual earthquake records.
|
토목공학
| null |
kci_detailed_000089.xml
|
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