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ART001705714
|
oai_dc
|
SSA-based stochastic subspace identification of structures from output-only vibration measurements
|
SSA-based stochastic subspace identification of structures from output-only vibration measurements
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chin-Hsiung Loh(National Taiwan University); Yi-Cheng Liu(National Taiwan University); Yi-Qing Ni(The Hong Kong Polytechnic University)"
] |
In this study an output-only system identification technique for civil structures under ambient vibrations is carried out, mainly focused on using the Stochastic Subspace Identification (SSI) based algorithms. A newly developed signal processing technique, called Singular Spectrum Analysis (SSA), capable to smooth a noisy signal, is adopted for preprocessing the measurement data. An SSA-based SSI algorithm with the aim of finding accurate and true modal parameters is developed through stabilization diagram which is constructed by plotting the identified system poles with increasing the size of data matrix. First, comparative study between different approaches, with and without using SSA to pre-process the data, on determining the model order and selecting the true system poles is examined in this study through numerical simulation. Finally, application of the proposed system identification task to the real large scale structure: Canton Tower, a benchmark problem for structural health monitoring of high-rise slender structures, using SSA-based SSI algorithm is carried out to extract the dynamic characteristics of the tower from output-only measurements.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001651967
|
oai_dc
|
Seismic performance of concrete frames reinforced with superelastic shape memory alloys
|
Seismic performance of concrete frames reinforced with superelastic shape memory alloys
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"M.A. Youssef(The University of Western Ontario); M.A. Elfeki(The University of Western Ontario)"
] |
Reinforced concrete (RC) framed buildings dissipate the seismic energy through yielding of the reinforcing bars. This yielding jeopardizes the serviceability of these buildings as it results in residual lateral deformations. Superelastic Shape Memory Alloys (SMAs) can recover inelastic strains by stress removal. Since SMA is a costly material, this paper defines the required locations of SMA bars in a typical RC frame to optimize its seismic performance in terms of damage scheme and seismic residual deformations. The intensities of five earthquakes causing failure to a typical RC six-storey building are defined and used to evaluate seven SMA design alternatives.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001651970
|
oai_dc
|
Tracking control of variable stiffness hysteretic-systems using linear-parameter-varying gain-scheduled controller
|
Tracking control of variable stiffness hysteretic-systems using linear-parameter-varying gain-scheduled controller
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"S. Nagarajaiah(Rice University); D.T.R. Pasala(Rice University); K. M. Grigoriadis(University of Houston)"
] |
Tracking control of systems with variable stiffness hysteresis using a gain-scheduled (GS) controller is developed in this paper. Variable stiffness hysteretic system is represented as quasi linear parameter dependent system with known bounds on parameters. Assuming that the parameters can be measured or estimated in real-time, a GS controller that ensures the performance and the stability of the closed-loop system over the entire range of parameter variation is designed. The proposed method is implemented on a springmass system which consists of a semi-active independently variable stiffness (SAIVS) device that exhibits hysteresis and precisely controllable stiffness change in real-time. The SAIVS system with variable stiffness hysteresis is represented as quasi linear parameter varying (LPV) system with two parameters: linear timevarying stiffness (parameter with slow variation rate) and stiffness of the friction-hysteresis (parameter with high variation rate). The proposed LPV-GS controller can accommodate both slow and fast varying parameter, which was not possible with the controllers proposed in the prior studies. Effectiveness of the proposed controller is demonstrated by comparing the results with a fixed robust H∞ controller that assumes the parameter variation as an uncertainty. Superior performance of the LPV-GS over the robust H∞ controller is demonstrated for varying stiffness hysteresis of SAIVS device and for different ranges of tracking displacements. The LPV-GS controller is capable of adapting to any parameter changes whereas the H∞ controller is effective only when the system parameters are in the vicinity of the nominal plant parameters for which the controller is designed. The robust H∞ controller becomes unstable under large parameter variations but the LPV-GS will ensure stability and guarantee the desired closed-loop performance.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001651969
|
oai_dc
|
Vibration analysis of a cracked beam with axial force and crack identification
|
Vibration analysis of a cracked beam with axial force and crack identification
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"J.K. Liu(Sun Yat-sen University); Z.R. Lu(Sun Yat-sen University)"
] |
A composite element method (CEM) is presented to analyze the free and forced vibrations of a cracked Euler-Bernoulli beam with axial force. The cracks are introduced by using Christides and Barr crack model with an adjustment on one crack parameter. The effects of the cracks and axial force on the reduction of natural frequencies and the dynamic responses of the beam are investigated. The time response sensitivities with respect to the crack parameters (i.e., crack location, crack depth) and the axial force are calculated. The natural frequencies obtained from the proposed method are compared with the analytical results in the literature, and good agreement is found. This study shows that the cracks in the beam may have significant effects on the dynamic responses of the beam. In the inverse problem, a response sensitivity-based model updating method is proposed to identify both a single crack and multiple cracks from measured dynamic responses. The cracks can be identified successfully even using simulated noisy acceleration responses.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001651968
|
oai_dc
|
A simple method to detect cracks in beam-like structures
|
A simple method to detect cracks in beam-like structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jiawei Xiang(Nagoya University); Toshiro Matsumoto(Nagoya University); Jiangqi Long(Wenzhou University); Yanxue Wang(Guilin University of Electronic Technology); Zhansi Jiang(Guilin University of Electronic Technology)"
] |
This study suggests a simple two-step method for structural vibration-based health monitoring for beam-like structures which only utilizes mode shape curvature and few natural frequencies of the structures in order to detect and localize cracks. The method is firstly based on the application of wavelet transform to detect crack locations from mode shape curvature. Then particle swarm optimization is applied to evaluate crack depth. As the Rayleigh quotient is introduced to estimate natural frequencies of cracked beams, the relationship of natural frequencies and crack depths can be easily obtained with only a simple formula. The method is demonstrated and validated numerically, using the numerical examples (cantilever beam and simply supported shaft) in the literature, and experimentally for a cantilever beam. Our results show that mode shape curvature and few estimated natural frequencies can be used to detect crack locations and depths precisely even under a certain level of noise. The method can be extended for health monitoring of other more complicated structures.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001651966
|
oai_dc
|
Investigations on critical speed suppressing by using electromagnetic actuators
|
Investigations on critical speed suppressing by using electromagnetic actuators
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jarir Mahfoud(Université de Lyon); Johan Der Hagopian(Université de Lyon)"
] |
The possibility of suppressing critical speeds by using electromagnetic actuators (EMAs) is assessed experimentally in this paper. The system studied is composed of a horizontal flexible shaft supported by two ball bearings at one end and one roller bearing that is located in a squirrel cage at the other end. Four identical EMAs supplied with constant current are utilized. The EMAs associated to the squirrel cage constitutes the hybrid bearing. Results obtained, show that the constant current, when applied to the EMAs, produces a shift of the first critical speed toward lower values. Moreover, the application of constant current for a speed interval around the critical speed enables a smooth run-up or run-down without crossing any resonance.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001712373
|
oai_dc
|
Semi-active control on long-span reticulated steel structures using MR dampers under multi-dimensional earthquake excitations
|
Semi-active control on long-span reticulated steel structures using MR dampers under multi-dimensional earthquake excitations
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Zhen Zhou(Southeast University); Shao-ping Meng(Southeast University); Jing Wu(Southeast University); Yong Zhao(Southeast University)"
] |
This paper focuses on the vibration control of long-span reticulated steel structures under multidimensional earthquake excitation. The control system and strategy are constructed based on Magneto- Rheological (MR) dampers. The LQR and Hrovat controlling algorithm is adopted to determine optimal MR damping force, while the modified Bingham model (MBM) and inverse neural network (INN) is proposed to solve the real-time controlling current. Three typical long-span reticulated structural systems are detailedly analyzed, including the double-layer cylindrical reticulated shell, single-layer spherical reticulated shell, and cable suspended arch-truss structure. Results show that the proposed control strategy can reduce the displacement and acceleration effectively for three typical structural systems. The displacement control effect under the earthquake excitation with different PGA is similar, while for the cable suspended arch-truss, the acceleration control effect increase distinctly with the earthquake excitation intensity. Moreover, for the cable suspended arch-truss, the strand stress variation can also be effectively reduced by the MR dampers, which is very important for this kind of structure to ensure that the cable would not be destroyed or relaxed.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001712364
|
oai_dc
|
A SMA-based actuation system for a fish robot
|
A SMA-based actuation system for a fish robot
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chan Hoang Le(Konkuk University); Hoon Cheol Park(Konkuk University); 박훈철(건국대학교)"
] |
We design and test a shape memory alloy (SMA)-based actuation system that can be used to propel a fish robot. The actuator in the system is composed of a 0.1 mm diameter SMA wire, a 0.5 mm-thick glass/epoxy composite strip, and a fixture frame. The SMA wire is installed in a pre-bent composite strip that provides initial tension to the SMA wire. The actuator can produce a blocking force of about 200 gram force (gf) and displacement of 3.5 mm at the center of the glass/epoxy strip for an 8 V application. The bending motion of the actuator is converted into the tail-beat motion of a fish robot through a linkage system. The fish robot is evaluated by measuring the tail-beat angle, swimming speed, and thrust produced by the tail-beat motion. The tail-beat angle is about 20o, the maximum swimming speed is about 1.6 cm/s, and the measured average thrust is about 0.4 gf when the fish robot is operated at 0.9 Hz.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001712371
|
oai_dc
|
Measuring high speed crack propagation in concrete fracture test using mechanoluminescent material
|
Measuring high speed crack propagation in concrete fracture test using mechanoluminescent material
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Wha-Jung Kim(Kyungpook National University); Chang Joon Lee(Kyungpook National University); 김지식(경북대학교); 이창준(충북대학교)"
] |
Measuring crack length in concrete fracture test is not a trivial problem due to high speed crack propagation. In this study, mechanoluminascent (ML) material, which emits visible light under stress condition, was employed to visualize crack propagation during concrete fracture test. Three-point bending test was conducted with a notched concrete beam specimen. The cracking images due to ML phenomenon were recorded by using a high speed camera as a function of time and external loadings. The experimental results successfully demonstrated the capability of ML material as a promising visualization tool for concrete crack propagation. In addition, an interesting cracking behavior of concrete bending fracture was observed in which the crack propagated fast while the load decreased slowly at early fracture stage.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001712374
|
oai_dc
|
Optimal shape of LCVA for vibration control of structures subjected to along wind excitation
|
Optimal shape of LCVA for vibration control of structures subjected to along wind excitation
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"박지훈(인천대학교); 민경원(단국대학교)"
] |
In this study, a procedure to design an optimal LCVA that maximizes the equivalent damping ratio added to the primary structure subjected to along-wind excitation is proposed. That design procedure does not only consider the natural frequency and damping ratio of the LCVA, but also the proportion of the Ushaped liquid, which is closely related to the participation ratio of the liquid mass in inertial force. In addition, constraints to ensure the U-shape of the liquid are considered in the design process, so that suboptimal solutions that violate the optimal tuning law partly are adopted as a candidate of the optimal LCVA. The proposed design procedure of the LCVA is applied to the control of the 76-story benchmark building, and the optimal proportions of the liquid shape under various design conditions are compared.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001712369
|
oai_dc
|
Vibration-based damage monitoring of harbor caisson structure with damaged foundation-structure interface
|
Vibration-based damage monitoring of harbor caisson structure with damaged foundation-structure interface
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"이소영(부경대학교); 김정태(부경대학교); Khac-Duy Nguyen(Pukyong National University); Thanh-Canh Huynh(Pukyong National University); Jin-Hak Yi(Korea Institute of Ocean Science and Technology (KIOST)); Sang-Hun Han(Korea Institute of Ocean Science and Technology (KIOST))"
] |
In this paper, vibration-based methods to monitor damage in foundation-structure interface of harbor caisson structure are presented. The following approaches are implemented to achieve the objective. Firstly, vibration-based damage monitoring methods utilizing a variety of vibration features are selected for harbor caisson structure. Autoregressive (AR) model for time-series analysis and power spectral density (PSD) for frequency-domain analysis are selected to detect the change in the caisson structure. Also, the changes in modal parameters such as natural frequency and mode shape are examined for damage monitoring in the structure. Secondly, the feasibility of damage monitoring methods is experimentally examined on an unsubmerged lab-scaled mono-caisson. Finally, numerical analysis of un-submerged mono-caisson, submerged mono-caisson and un-submerged interlocked multiple-caissons are carried out to examine the effect of boundary-dependent parameters on the damage monitoring of harbor caisson structures.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001685288
|
oai_dc
|
Vibration mitigation of composite laminated satellite solar panels using distributed piezoelectric patches
|
Vibration mitigation of composite laminated satellite solar panels using distributed piezoelectric patches
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"M.A. Foda(King Saud University); K.A. Alsaif(King Saud University)"
] |
Satellites with flexible lightweight solar panels are sensitive to vibration that is caused by internal actuators such as reaction or momentum wheels which are used to control the attitude of the satellite. Any infinitesimal amount of unbalance in the reaction wheels rotors will impose a harmonic excitation which may interact with the solar panels structure. Therefore, quenching the solar panel’s vibration is of a practical importance. In the present work, the panels are modeled as laminated composite beam using first-order shear deformation laminated plate theory which accounts for rotational inertia as well as shear deformation effects. The vibration suppression is achieved by bonding patches of piezoelectric material with suitable dimensions at selected locations along the panel. These patches are actuated by driving control voltages. The governing equations for the system are formulated and the dynamic Green’s functions are used to present an exact yet simple solution for the problem. A guide lines is proposed for determining the values of the driving voltage in order to suppress the induced vibration.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001685287
|
oai_dc
|
Probabilistic optimal safety valuation based on stochastic finite element analysis of steel cable-stayed bridges
|
Probabilistic optimal safety valuation based on stochastic finite element analysis of steel cable-stayed bridges
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Sung-Ho Han(Korean Intellectual Property Office); Myung-Seok Bang(Korea National University of Transportation)"
] |
This study was intended to efficiently perform the probabilistic optimal safety assessment of steel cable-stayed bridges (SCS bridges) using stochastic finite element analysis (SFEA) and expected life-cycle cost (LCC) concept. To that end, advanced probabilistic finite element algorithm (APFEA) which enables to execute the static and dynamic SFEA considering aleatory uncertainties contained in random variable was developed. APFEA is the useful analytical means enabling to conduct the reliability assessment (RA) in a systematic way by considering the result of SFEA based on linearity and nonlinearity of before or after introducing initial tensile force. The appropriateness of APFEA was verified in such a way of comparing the result of SFEA and that of Monte Carlo Simulation (MCS). The probabilistic method was set taking into account of analytical parameters. The dynamic response characteristic by probabilistic method was evaluated using ASFEA, and RA was carried out using analysis results, thereby quantitatively calculating the probabilistic safety. The optimal design was determined based on the expected LCC according to the results of SFEA and RA of alternative designs. Moreover, given the potential epistemic uncertainty contained in safety index, failure probability and minimum LCC, the sensitivity analysis was conducted and as a result, a critical distribution phase was illustrated using a cumulative-percentile.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001685289
|
oai_dc
|
Seismic safety assessment of eynel highway steel bridge using ambient vibration measurements
|
Seismic safety assessment of eynel highway steel bridge using ambient vibration measurements
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ahmet Can Altuni sik(Karadeniz Technical University); Alemdar Bayraktar(Karadeniz Technical University); Hasan Özdemir(Prokon Engineering and Consultancy Inc.)"
] |
In this paper, it is aimed to determine the seismic behaviour of highway bridges by nondestructive testing using ambient vibration measurements. Eynel Highway Bridge which has arch type structural system with a total length of 216 m and located in the Ayvaclk county of Samsun, Turkey is selected as an application. The bridge connects the villages which are separated with Suat U urlu Dam Lake. A three dimensional finite element model is first established for a highway bridge using project drawings and an analytical modal analysis is then performed to generate natural frequencies and mode shapes in the three orthogonal directions. The ambient vibration measurements are carried out on the bridge deck under natural excitation such as traffic, human walking and wind loads using Operational Modal Analysis. Sensitive seismic accelerometers are used to collect signals obtained from the experimental tests. To obtain experimental dynamic characteristics, two output-only system identification techniques are employed namely, Enhanced Frequency Domain Decomposition technique in the frequency domain and Stochastic Subspace Identification technique in time domain. Analytical and experimental dynamic characteristic are compared with each other and finite element model of the bridge is updated by changing of boundary conditions to reduce the differences between the results. It is demonstrated that the ambient vibration measurements are enough to identify the most significant modes of highway bridges. After finite element model updating, maximum differences between the natural frequencies are reduced averagely from 23% to 3%. The updated finite element model reflects the dynamic characteristics of the bridge better, and it can be used to predict the dynamic response under complex external forces. It is also helpful for further damage identification and health condition monitoring. Analytical model of the bridge before and after model updating is analyzed using 1992 Erzincan earthquake record to determine the seismic behaviour. It can be seen from the analysis results that displacements increase by the height of bridge columns and along to middle point of the deck and main arches. Bending moments have an increasing trend along to first and last 50 m and have a decreasing trend long to the middle of the main arches.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001685291
|
oai_dc
|
Experimental identification of rare-earth magnetic suspensions for micro and meso scale levitating systems
|
Experimental identification of rare-earth magnetic suspensions for micro and meso scale levitating systems
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chamila Siyambalapitiya(University of South Florida); Giorgio De Pasquale(Politecnico di Torino); Aurelio Somà(Politecnico di Torino)"
] |
Magnetic suspensions based on passive levitation of diamagnetic materials on permanent magnets provide attractive systems for several applications on the micro and meso scales. The magnetic properties of these kinds of suspensions dramatically reduce the global mechanical stiffness of the devices providing significant effects on their dynamic response. The goal of this paper is to investigate the static and dynamic behavior of magnetic suspensions with respect to its dependant parameters. Experimental measurements have been performed on the response of dedicated prototypes where the geometrical dimensions and magnetic field strength have been intended as variable parameters. Some benefits have been documented in the fields of energy harvesting and inertial sensing, while additional applications of magnetic suspensions are under investigation.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001685290
|
oai_dc
|
Evaluation and analytical approximation of Tuned Mass Damper performance in an earthquake environment
|
Evaluation and analytical approximation of Tuned Mass Damper performance in an earthquake environment
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Alexander Tributsch(University of Innsbruck); Christoph Adam(University of Innsbruck)"
] |
This paper aims at assessing the seismic performance of Tuned Mass Dampers (TMDs) based on sets of recorded ground motions. For the simplest configuration of a structure-TMD assembly, in a comprehensive study characteristic response quantities are derived and statistically evaluated. Optimal tuning of TMD parameters is discussed and evaluated. The response reduction by application of a TMD is quantified depending on the structural period, inherent damping of the stand-alone structure, and ratio of TMD mass to structural mass. The effect of detuning on the stroke of the TMD and on the structural response is assessed and quantified. It is verified that a TMD damping coefficient larger than the optimal one reduces the peak deflection of the TMD spring significantly, whereas the response reduction of the main structure remains almost unaffected. Analytical relations for quantifying the effect of a TMD are derived and subsequently evaluated. These relations allow the engineer in practice a fast and yet accurate assessment of the TMD performance.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001632019
|
oai_dc
|
Exact solutions of free vibration of rotating multilayered FGM cylinders
|
Exact solutions of free vibration of rotating multilayered FGM cylinders
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chih-Ping Wu(National Cheng Kung University); Hao-Yuan Li(National Cheng Kung University)"
] |
A modified Pagano method is developed for the three-dimensional (3D) free vibration analysis of simply-supported, multilayered functionally graded material (FGM) circular hollow cylinders with a constant rotational speed with respect to the meridional direction of the cylinders. The material properties of each FGM layer constituting the cylinders are regarded as heterogeneous through the thickness coordinate, and then specified to obey a power-law distribution of the volume fractions of the constituents, and the effects of centrifugal and Coriolis accelerations, as well as the initial hoop stress due to rotation, are considered. The Pagano method, which was developed for the static and dynamic analyses of multilayered composite plates, is modified in that a displacement-based formulation is replaced by a mixed formulation, the complex-valued solutions of the system equations are transferred to the real-valued solutions, a successive approximation method is adopted to extend its application to FGM cylinders, and a propagator matrix method is developed to reduce the time needed for its implementation. These modifications make the Pagano method feasible for multilayered FGM cylinders, and the computation in the implementation is independent of the total number of the layers, thus becoming less time-consuming than usual.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001632020
|
oai_dc
|
Studying the nonlinear behavior of the functionally graded annular plates with piezoelectric layers as a sensor and actuator under normal pressure
|
Studying the nonlinear behavior of the functionally graded annular plates with piezoelectric layers as a sensor and actuator under normal pressure
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"M. Arefi(Tarbiat Modares University); G.H. Rahimi(Tarbiat Modares University)"
] |
The present paper deals with the nonlinear analysis of the functionally graded piezoelectric (FGP) annular plate with two smart layers as sensor and actuator. The normal pressure is applied on the plate. The geometric nonlinearity is considered in the strain-displacement equations based on Von-Karman assumption. The problem is symmetric due to symmetric loading, boundary conditions and material properties. The radial and transverse displacements are supposed as two dominant components of displacement. The constitutive equations are derived for two sections of the plate, individually. Total energy of the system is evaluated for elastic solid and piezoelectric sections in terms of two components of displacement and electric potential. The response of the system can be obtained using minimization of the energy of system with respect to amplitude of displacements and electric potential. The distribution of all material properties is considered as power function along the thickness direction. Displacement-load and electric potential-load curves verify the nonlinearity nature of the problem. The response of the linear analysis is investigated and compared with those results obtained using the nonlinear analysis. This comparison justifies the necessity of a nonlinear analysis. The distribution of the displacements and electric potential in terms of non homogenous index indicates that these curves converge for small value of piezoelectric thickness with respect to elastic solid thickness.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001632031
|
oai_dc
|
Electrically-induced actuation for open-loop control to cancel self-excitation vibration
|
Electrically-induced actuation for open-loop control to cancel self-excitation vibration
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Kanjuro Makihara(Tohoku University); Horst Ecker(Vienna University of Technology)"
] |
This paper focuses on the actuation system combined with a piezoelectric transducer and an electric circuit, which leads to a new insight; the electric actuation system is equivalent to mechanical variablestiffness actuation systems. By controlling the switch in the circuit, the electric status of the piezoelectric transducer is changed, and consequently a variable-stiffness mechanism is achieved on the electric actuator. This proposed actuator features a shift in the equilibrium point of force, while conventional electricallyinduced variable-stiffness actuators feature the variation of the stiffness value. We intensively focus on the equilibrium shift in the actuation system, which has been neglected. The stiffness of the variable-stiffness actuator is periodically modulated by controlling the switch, to suppress the vibration of the system in an open-loop way. It is proved that this electric actuator is equivalent to its mechanical counterpart, and that the electrical version has some practical advantages over the mechanical one. Furthermore, another kind of electrically-induced variable-stiffness actuator, using an energy-recycling mechanism is also discussed from the viewpoint of open-loop vibration control. Extensive numerical simulations provide comprehensive assessment on both electrically-induced variable-stiffness actuators employed for open-loop vibration control.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001632027
|
oai_dc
|
Solar-powered multi-scale sensor node on Imote2 platform for hybrid SHM in cable-stayed bridge
|
Solar-powered multi-scale sensor node on Imote2 platform for hybrid SHM in cable-stayed bridge
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Duc-Duy Ho(Pukyong National University); 김정태(부경대학교); Khac-Duy Nguyen(Pukyong National University); 홍동수(부경대학교); 이소영(부경대학교); 신성우(부경대학교); 윤정방(한국과학기술원); Masanobu Shinozuka(Univ. of California); Po-Young Lee(Pukyong National University)"
] |
In this paper, solar-powered, multi-scale, vibration-impedance sensor node on Imote2 platform is presented for hybrid structural health monitoring (SHM) in cable-stayed bridge. In order to achieve the objective, the following approaches are proposed. Firstly, vibration- and impedance-based hybrid SHM methods are briefly described. Secondly, the multi-scale vibration and impedance sensor node on Imote2- platform is presented on the design of hardware components and embedded software for vibration- and impedance-based SHM. In this approach, a solar-powered energy harvesting is implemented for autonomous operation of the smart sensor nodes. Finally, the feasibility and practicality of the smart sensor-based SHM system is evaluated on a full-scale cable-stayed bridge, Hwamyung Bridge in Korea. Successful level of wireless communication and solar-power supply for smart sensor nodes are verified. Also, vibration and impedance responses measured from the target bridge which experiences various weather conditions are examined for the robust long-term monitoring capability of the smart sensor system.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001632029
|
oai_dc
|
Design tables and charts for uniform and non-uniform tuned liquid column dampers in harmonic pitching motion
|
Design tables and charts for uniform and non-uniform tuned liquid column dampers in harmonic pitching motion
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jong-Cheng Wu(Tamkang University); Yen-Po Wang(National Chiao Tung University); Yi-Hsuan Chen(National Chiao Tung University)"
] |
In the first part of the paper, the optimal design parameters for tuned liquid column dampers (TLCD) in harmonic pitching motion were investigated. The configurations in design tables include uniform and non-uniform TLCDs with cross-sectional ratios of 0.3, 0.6, 1, 2 and 3 for the design in different situations. A closed-form solution of the structural response was used for performing numerical optimization. The results from optimization indicate that the optimal structural response always occurs when the two resonant peaks along the frequency axis are equal. The optimal frequency tuning ratio, optimal head loss coefficient, the corresponding response and other useful quantities are constructed in design tables as a guideline for practitioners. As the value of the head loss coefficient is only available through experiments, in the second part of the paper, the prediction of head loss coefficients in the form of a design chart are proposed based on a series of large scale tests in pitching base motions, aiming to ease the predicament of lacking the information of head loss for those who wishes to make designs without going through experimentation. A large extent of TLCDs with cross-sectional ratios of 0.3, 0.6, 1, 2 and 3 and orifice blocking ratios ranging from 0%, 20%,40%, 60% to 80% were inspected by means of a closed-form solution under harmonic base motion for identification. For the convenience of practical use, the corresponding empirical formulas for predicting head loss coefficients of TLCDs in relation to the cross-sectional ratio and the orifice blocking ratio were also proposed. For supplemental information to horizontal base motion, the relation of head loss values versus blocking ratios and the corresponding empirical formulas were also presented in the end.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001661174
|
oai_dc
|
On FEM modeling of piezoelectric actuators and sensors for thin-walled structures
|
On FEM modeling of piezoelectric actuators and sensors for thin-walled structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Dragan Marinkovic(University of Niš); Zoran Marinkovic(University of Niš)"
] |
Thin-walled adaptive structures render a large and important group of adaptive structures. Typical material system used for them is a composite laminate that includes piezoelectric material based sensors and actuators. The piezoelectric active elements are in the form of thin patches bonded onto or embedded into the structure. Among different types of patches, the paper considers those polarized in the thickness direction. The finite element method (FEM) imposed itself as an essential technical support for the needs of structural design. This paper gives a brief description of a developed shell type finite element for active/adaptive thin-walled structures and the element is, furthermore, used as a tool to consider the aspect of mesh distortion over the surface of actuators and sensors. The aspect is of significance for simulation of behavior of adaptive structures and implementation of control algorithms.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001661185
|
oai_dc
|
Damage detection for pipeline structures using optic-based active sensing
|
Damage detection for pipeline structures using optic-based active sensing
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"이현석(한국과학기술원); 손훈(한국과학기술원)"
] |
This study proposes an optics-based active sensing system for continuous monitoring of underground pipelines in nuclear power plants (NPPs). The proposed system generates and measures guided waves using a single laser source and optical cables. First, a tunable laser is used as a common power source for guided wave generation and sensing. This source laser beam is transmitted through an optical fiber, and the fiber is split into two. One of them is used to actuate macro fiber composite (MFC) transducers for guided wave generation, and the other optical fiber is used with fiber Bragg grating (FBG) sensors to measure guided wave responses. The MFC transducers placed along a circumferential direction of a pipe at one end generate longitudinal and flexural modes, and the corresponding responses are measured using FBG sensors instrumented in the same configuration at the other end. The generated guided waves interact with a defect, and this interaction causes changes in response signals. Then, a damage-sensitive feature is extracted from the response signals using the axi-symmetry nature of the measured pitch-catch signals. The feasibility of the proposed system has been examined through a laboratory experiment.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001661183
|
oai_dc
|
Synchrosqueezed wavelet transform for frequency and damping identification from noisy signals
|
Synchrosqueezed wavelet transform for frequency and damping identification from noisy signals
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Luis A. Montejo(University of Puerto Rico at Mayagüez); Aidcer L. Vidot-Vega(University of Puerto Rico at Mayagüez)"
] |
Identification of vibration parameters from the analysis of the dynamic response of a structure plays a key role in current health monitoring systems. This study evaluates the capabilities of the recently developed Synchrosqueezed Wavelet Transform (SWT) to extract instant frequencies and damping values from the simulated noise-contaminated response of a structure. Two approaches to estimate the modal damping ratio from the results of the SWT are presented. The results obtained are compared to other signal processing methods based on Continuous Wavelet (CWT) and Hilbert-Huang (HHT) transforms. It was found that the time-frequency representation obtained via SWT is sharped than the obtained using just the CWT and it allows a more robust extraction of the individual modal responses than using the HHT. However, the identification of damping ratios is more stable when the CWT coefficients are employed.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001661172
|
oai_dc
|
An optical fibre monitoring system for evaluating the performance of a soil nailed slope
|
An optical fibre monitoring system for evaluating the performance of a soil nailed slope
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Hong-Hu Zhu(Nanjing University); Albert N.L. Ho(Ove Arup & Partners Hong Kong Limited); Jian-Hua Yin(The Hong Kong Polytechnic University); H.W. Sun(Government of the Hong Kong Special Administrative Region); Hua-Fu Pei(The Hong Kong Polytechnic University); Cheng-Yu Hong(The Hong Kong Polytechnic University)"
] |
Conventional geotechnical instrumentation techniques available for monitoring of slopes, especially soil-nailed slopes have limitations such as electromagnetic interference, low accuracy, poor longterm reliability and difficulty in mounting a series of strain sensors on a soil nail bar with a small-diameter. This paper presents a slope monitoring system based on fibre Bragg grating (FBG) sensing technology. This monitoring system is designed to perform long-term monitoring of slope movements, strains along soil nails, and other slope reinforcement elements. All these FBG sensors are fabricated and calibrated in laboratory and a trial of this monitoring system has been successfully conducted on a roadside slope in Hong Kong. As part of the slope stability improvement works, soil nails and a toe support soldier-pile wall were constructed. During the slope works, more than 100 FBG sensors were installed on a soil nail, a soldier pile, and an in- place inclinometer. The paper presents the layout and arrangement of the instruments as well as the installation procedures adopted. Monitoring data have been collected since March 2008. This trial has demonstrated the great potential of the optical fibre monitoring system for long-term monitoring of slope performance. The advantages of the slope monitoring system and experience gained in the field implementation are also discussed in the paper.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001661179
|
oai_dc
|
Exact solution of a thick walled functionally graded piezoelectric cylinder under mechanical, thermal and electrical loads in the magnetic field
|
Exact solution of a thick walled functionally graded piezoelectric cylinder under mechanical, thermal and electrical loads in the magnetic field
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"M. Arefi(Tarbiat Modares University); G.H. Rahimi(Tarbiat Modares University); M.J. Khoshgoftar(Tarbiat Modares University)"
] |
The present paper deals with the analytical solution of a functionally graded piezoelectric (FGP) cylinder in the magnetic field under mechanical, thermal and electrical loads. All mechanical, thermal and electrical properties except Poisson ratio can be varied continuously and gradually along the thickness direction of the cylinder based on a power function. The cylinder is assumed to be axisymmetric. Steady state heat transfer equation is solved by considering the appropriate boundary conditions. Using Maxwell electro dynamic equation and assumed magnetic field along the axis of the cylinder, Lorentz’s force due to magnetic field is evaluated for non homogenous state. This force can be employed as a body force in the equilibrium equation. Equilibrium and Maxwell equations are two fundamental equations for analysis of the problem. Comprehensive solution of Maxwell equation is considered in the present paper for general states of non homogeneity. Solution of governing equations may be obtained using solution of the characteristic equation of the system. Achieved results indicate that with increasing the non homogenous index, different mechanical and electrical components present different behaviors along the thickness direction. FGP can control the distribution of the mechanical and electrical components in various structures with good precision. For intelligent properties of functionally graded piezoelectric materials, these materials can be used as an actuator, sensor or a component of piezo motor in electromechanical systems.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001681818
|
oai_dc
|
A non-destructive method for elliptical cracks identification in shafts based on wave propagation signals and genetic algorithms
|
A non-destructive method for elliptical cracks identification in shafts based on wave propagation signals and genetic algorithms
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Belén Muñoz-Abella(Universidad Carlos III de Madrid); Lourdes Rubio(Universidad Carlos III de Madrid); Patricia Rubio(Universidad Carlos III de Madrid)"
] |
The presence of crack-like defects in mechanical and structural elements produces failures during their service life that in some cases can be catastrophic. So, the early detection of the fatigue cracks is particularly important because they grow rapidly, with a propagation velocity that increases exponentially, and may lead to long out-of-service periods, heavy damages of machines and severe economic consequences. In this work, a non-destructive method for the detection and identification of elliptical cracks in shafts based on stress wave propagation is proposed. The propagation of a stress wave in a cracked shaft has been numerically analyzed and numerical results have been used to detect and identify the crack through the genetic algorithm optimization method. The results obtained in this work allow the development of an on-line method for damage detection and identification for cracked shaft-like components using an easy and portable dynamic testing device.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001681819
|
oai_dc
|
A comparative study of dragonfly inspired flapping wings actuated by single crystal piezoceramic
|
A comparative study of dragonfly inspired flapping wings actuated by single crystal piezoceramic
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Sujoy Mukherjee(Indian Institute of Science); Ranjan Ganguli(Indian Institute of Science)"
] |
A dragonfly inspired flapping wing is investigated in this paper. The flapping wing is actuated from the root by a PZT-5H and PZN-7%PT single crystal unimorph in the piezofan configuration. The nonlinear governing equations of motion of the smart flapping wing are obtained using the Hamilton’s principle.
These equations are then discretized using the Galerkin method and solved using the method of multiple scales. Dynamic characteristics of smart flapping wings having the same size as the actual wings of three different dragonfly species Aeshna Multicolor, Anax Parthenope Julius and Sympetrum Frequens are analyzed using numerical simulations. An unsteady aerodynamic model is used to obtain the aerodynamic forces. Finally, a comparative study of performances of three piezoelectrically actuated flapping wings is performed.
The numerical results in this paper show that use of PZN-7%PT single crystal piezoceramic can lead to considerable amount of wing weight reduction and increase of lift and thrust force compared to PZT-5H material. It is also shown that dragonfly inspired smart flapping wings actuated by single crystal piezoceramic are a viable contender for insect scale flapping wing micro air vehicles.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001681814
|
oai_dc
|
Beam-rotating machinery system active vibration control using a fuzzy input estimation method and LQG control technique combination
|
Beam-rotating machinery system active vibration control using a fuzzy input estimation method and LQG control technique combination
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ming-Hui Lee(Chinese Military Academy)"
] |
This study proposes an active control method to suppress beam-rotating machinery system vibrations. The present control method is a combination of the fuzzy input estimation method (FIEM) and linear quadratic Gaussian problem (LQG) algorithms. The FIEM can estimate the unknown input and optimal states by measuring the dynamic displacement, the optimal estimated states into the feedback control; thereby obtaining the optimal control force for a random linear system. Active vibration control of a beam-rotating machinery system is performed to verify the feasibility and effectiveness of the proposed algorithm. The simulation results demonstrate that the proposed method can suppress vibrations in a beam-machine system more efficiently than the conventional LQG method.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001681816
|
oai_dc
|
Adaptive MR damper cable control system based on piezoelectric power harvesting
|
Adaptive MR damper cable control system based on piezoelectric power harvesting
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Xinchun Guan(Harbin Institute of Technology); Yonghu Huang(Harbin Institute of Technology); Hui Li(Harbin Institute of Technology); Jinping Ou(Dalian University of Technology)"
] |
To reduce the vibration of cable-stayed bridges, conventional magnetorheological (MR) damper control system (CMRDS), with separate power supply, sensors and controllers, is widely investigated. In this paper, to improve the reliability and performance of the control system, one adaptive MR damper control system (AMRDS) consisting of MR damper and piezoelectric energy harvester (PEH) is proposed. According to piezoelectric effect, PEH can produce energy for powering MR damper. The energy is proportional to the product of the cable displacement and velocity. Due to the damping force changing with the energy, the new system can be adjustable to reduce the cable vibration. Compared with CMRDS, the new system is structurally simplified, replacing external sensor, power supply and controller with PEH. In the paper, taking the N26 cable of Shandong Binzhou Yellow River Bridge as example, the design method for the whole AMRDS is given,and simple formulas for PEH are derived. To verify the effectiveness of the proposed adaptive control system, the performance is compared with active control case and simple Bang-Bang semi-active control case. It is shown that AMRDS is better than simple Bang-Bang semi-active control case, and still needed to be improved in comparison with active control case.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001681812
|
oai_dc
|
Wireless links for global positioning system receivers
|
Wireless links for global positioning system receivers
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Fabio Casciati(University of Pavia); Lijun Wu(University of Pavia)"
] |
Given an object, its positioning in the space is a main concern in structural monitoring and a required feedback in structural health monitoring, structural control and robotics. In addition, to make the sensor unit wireless is a crucial issue for advanced applications. This paper deals with the exploitation of wireless transmission technology to long-term monitoring GPS (Global Positioning System) receivers - like the Leica GMX 902 and the Leica GRX 1200-pro. These GPS receivers consist of five parts: antenna, receiver,user client computer, interface and power supply. The antenna is mounted on the object to be monitored and is connected with the receiver by a coaxial-cable through which the radio frequency signals are transmitted. The receiver unit acquires, tracks and demodulates the satellite signals and provides, through an interface which in this paper is made wireless, the resulting GPS raw data to the user client computer for being further processed by a suitable positioning algorithm. The power supply reaches the computer by a wired link, while the other modules rely on batteries re-charged by power harvesting devices. Two wireless transmission systems, the 24XStream and the CC1110, are applied to replace the cable transmission between the receiver and the user client computer which up to now was the only market offer. To verify the performance and the reliability of this wireless transmission system, some experiments are conducted. The results show a successful cable replacement.
|
토목공학
| null |
http://dx.doi.org/
|
kci_detailed_000091.xml
|
||
ART001576203
|
oai_dc
|
Damage observability, localization and assessment based on eigenfrequencies and eigenvectors curvatures
|
Damage observability, localization and assessment based on eigenfrequencies and eigenvectors curvatures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jacopo Ciambella(Università di Roma); Fabrizio Vestroni(Università di Roma); Stefano Vidoli(Università di Roma)"
] |
A technique for damage localization and assessment based on measurements of both eigenvectors curvatures and eigenfrequencies is proposed. The procedure is based on two successive steps: a model independent localization, based on changes of modal curvatures, and the solution of a one-dimensional minimization problem to evaluate damage intensity. The observability properties of damage parameters is discussed and, accordingly, a suitable change of coordinates is introduced. The proposed technique is illustrated with reference to a cantilever Euler beam endowed with a set of piezoelectric transducers. To assess the robustness of the algorithm, a parametric study of the identification errors with respect to the number of transducers and to the number of considered modal quantities is carried out with both clean and noisecorrupted data.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001576206
|
oai_dc
|
Direct assignment of the dynamics of a laboratorial model using an active bracing system
|
Direct assignment of the dynamics of a laboratorial model using an active bracing system
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"C. Moutinho(Faculty of Engineering of University of Porto (FEUP)); A. Cunha(Faculty of Engineering of University of Porto (FEUP)); E. Caetano(Faculty of Engineering of University of Porto (FEUP))"
] |
This article describes the research work involving the implementation of an Active Bracing System aimed at the modification of the initial dynamics of a laboratorial building structure to a new desired dynamics. By means of an adequate control force it is possible to assign an entirely new dynamics to a system by moving its natural frequencies and damping ratios to different values with the purpose of achieving a better overall structural response to external loads. In Civil Engineering applications, the most common procedures for controlling vibrations in structures include changing natural frequencies in order to avoid resonance phenomena and increasing the damping ratios of the critical vibration modes. In this study, the actual implementation of an active system is demonstrated, which is able to perform such modifications in a wide frequency range; to this end, a plane frame physical model with 4 degrees-of-freedom is used. The Active Bracing System developed is actuated by a linear motor controlled by an algorithm based on pole assignment strategy. The efficiency of this control system is verified experimentally by analyzing the control effect obtained with the modification of the initial dynamic parameters of the plane frame and observing the subsequent structural response.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001576202
|
oai_dc
|
Displacement-based design approach for highway bridges with SMA isolators
|
Displacement-based design approach for highway bridges with SMA isolators
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jin-long Liu(The Hong Kong Polytechnic University); Songye Zhu(The Hong Kong Polytechnic University); You-lin Xu(The Hong Kong Polytechnic University); Yunfeng Zhang(University of Maryland)"
] |
As a practical and effective seismic resisting technology, the base isolation system has seen extensive applications in buildings and bridges. However, a few problems associated with conventional leadrubber bearings have been identified after historical strong earthquakes, e.g., excessive permanent deformations of bearings and potential unseating of bridge decks. Recently the applications of shape memory alloys (SMA) have received growing interest in the area of seismic response mitigation. As a result, a variety of SMA-based base isolators have been developed. These novel isolators often lead to minimal permanent deformations due to the self-centering feature of SMA materials. However, a rational design approach is still missing because of the fact that conventional design method cannot be directly applied to these novel devices. In light of this limitation, a displacement-based design approach for highway bridges with SMA isolators is proposed in this paper. Nonlinear response spectra, derived from typical hysteretic models for SMA, are employed in the design procedure. SMA isolators and bridge piers are designed according to the prescribed performance objectives. A prototype reinforced concrete (RC) highway bridge is designed using the proposed design approach. Nonlinear dynamic analyses for different seismic intensity levels are carried out using a computer program called “OpenSees”. The efficacy of the displacement-based design approach is validated by numerical simulations. Results indicate that a properly designed RC highway bridge with novel SMA isolators may achieve minor damage and minimal residual deformations under frequent and rare earthquakes. Nonlinear static analysis is also carried out to investigate the failure mechanism and the self-centering ability of the designed highway bridge.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001576209
|
oai_dc
|
Identification of multiple sources in a plate structure using pre-filtering process for reduction of interference wave
|
Identification of multiple sources in a plate structure using pre-filtering process for reduction of interference wave
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"이상권(인하대학교); Y.S. Moon(Inha University); J.H. Park(Inha University)"
] |
This paper presents novel research into the source localization of multiple impacts. Source localization technology for single impact loads in a plate structure has been used for health monitoring. Most of research on source localization has been focused only on the localization of single impacts. Overlapping of dispersive waves induced by multiple impacts and reflection of those waves from the edge of the plate make it difficult to localize the sources of multiple impacts using traditional source localization technology. The method solving the overlapping problem and the reflection problem is presented in the paper. The suggested method is based on pre-signal processing technology using band pass filter and optimal filter. Results from numerical simulation and from experimentation are presented, and these verify the capability of the proposed method.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001576199
|
oai_dc
|
State-space formulation for simultaneous identification of both damage and input force from response sensitivity
|
State-space formulation for simultaneous identification of both damage and input force from response sensitivity
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Z.R. Lu(Sun Yat-sen University); J.K. Liu(Sun Yat-sen University); M. Huang(Sun Yat-sen University)"
] |
A new method for both local damage(s) identification and input excitation force identification of beam structures is presented using the dynamic response sensitivity-based finite element model updating method. The state-space approach is used to calculate both the structural dynamic responses and the responses sensitivities with respect to structural physical parameters such as elemental flexural rigidity and with respect to the force parameters as well. The sensitivities of displacement and acceleration responses with respect to structural physical parameters are calculated in time domain and compared to those by using Newmark method in the forward analysis. In the inverse analysis, both the input excitation force and the local damage are identified from only several acceleration measurements. Local damages and the input excitation force are identified in a gradient-based model updating method based on dynamic response sensitivity. Both computation simulations and the laboratory work illustrate the effectiveness and robustness of the proposed method.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001552362
|
oai_dc
|
A multi-functional cable-damper system for vibration mitigation, tension estimation and energy harvesting
|
A multi-functional cable-damper system for vibration mitigation, tension estimation and energy harvesting
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"정형조(한국과학기술원); 김인호(한국과학기술원); Jeong-Hoi Koo(Miami University of Ohio)"
] |
This paper presents a multi-functional system, consisting of a magnetorheological (MR) damper and an electromagnetic induction (EMI) device, and its applications in stay cables. The proposed system is capable of offering multiple functions: (1) mitigating excessive vibrations of cables, (2) estimating cable tension, and (3) harvesting energy for wireless sensors used health monitoring of cable-stayed bridges. In the proposed system, the EMI device, consisting of permanent magnets and a solenoid coil, can converts vibration energy into electrical energy (i.e., induced emf); hence, it acts as an energy harvesting system. Moreover, the cable tension can be estimated by using the emf signals obtained from the EMI device. In addition, the MR damper, whose damping property is controlled by the harvested energy from the EMI device, can effectively reduce excessive cable vibrations. In this study, the multi-functionality of the proposed system is experimentally evaluated by conducting a shaking table test as well as a full-scale stay cable in a laboratory setting. In the shaking table experiment, the energy harvesting capability of the EMI device for wireless sensor nodes is investigated. The performance on the cable tension estimation and the vibration mitigation are evaluated using the full-scale cable test setup. The test results show that the proposed system can sufficiently generate and store the electricity for operating a wireless sensor node twice per day, significantly alleviate vibration of a stay cable (by providing about 20% larger damping compared to the passive optimal case), and estimate the cable tension accurately within a 2.5% error.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001552363
|
oai_dc
|
Hybrid acceleration-impedance sensor nodes on Imote2- platform for damage monitoring in steel girder connections
|
Hybrid acceleration-impedance sensor nodes on Imote2- platform for damage monitoring in steel girder connections
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"김정태(부경대학교); 박재형(부경대학교); 홍동수(부경대학교); Duc-Duy Ho(Pukyong National University)"
] |
Hybrid acceleration-impedance sensor nodes on Imote2-platform are designed for damage monitoring in steel girder connections. Thus, the feasibility of the sensor nodes is examined about its performance for vibration-based global monitoring and impedance-based local monitoring in the structural systems. To achieve the objective, the following approaches are implemented. First, a damage monitoring scheme is described in parallel with global vibration-based methods and local impedance-based methods. Second, multi-scale sensor nodes that enable combined acceleration-impedance monitoring are described on the design of hardware components and embedded software to operate. Third, the performances of the multi-scale sensor nodes are experimentally evaluated from damage monitoring in a lab-scaled steel girder with bolted connection joints.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001552364
|
oai_dc
|
Passive shape control of force-induced harmonic lateral vibrations for laminated piezoelastic Bernoulli-Eulerbeams-theory and practical relevance
|
Passive shape control of force-induced harmonic lateral vibrations for laminated piezoelastic Bernoulli-Eulerbeams-theory and practical relevance
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"J. Schoeftner(Johannes Kepler University of Linz); H. Irschik(Johannes Kepler University of Linz)"
] |
The present paper is devoted to vibration canceling and shape control of piezoelastic slender beams. Taking into account the presence of electric networks, an extended electromechanically coupled Bernoulli-Euler beam theory for passive piezoelectric composite structures is shortly introduced in the first part of our contribution. The second part of the paper deals with the concept of passive shape control of beams using shaped piezoelectric layers and tuned inductive networks. It is shown that an impedance matching and a shaping condition must be fulfilled in order to perfectly cancel vibrations due to an arbitrary harmonic load for a specific frequency. As a main result of the present paper, the correctness of the theory of passive shape control is demonstrated for a harmonically excited piezoelelastic cantilever by a finite element calculation based on one-dimensional Bernoulli-Euler beam elements, as well as by the commercial finite element code of ANSYS using three-dimensional solid elements. Finally, an outlook for the practical importance of the passive shape control concept is given: It is shown that harmonic vibrations of a beam with properly shaped layers according to the presented passive shape control theory, which are attached to an resistor-inductive circuit (RL-circuit), can be significantly reduced over a large frequency range compared to a beam with uniformly distributed piezoelectric layers.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001552359
|
oai_dc
|
Seismic behaviour of repaired superelastic shape memory alloy reinforced concrete beam-column joint
|
Seismic behaviour of repaired superelastic shape memory alloy reinforced concrete beam-column joint
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Moncef Nehdi(The University of Western Ontario); M. Shahria Alam(The University of British Columbia); Maged A. Youssef(The University of Western Ontario)"
] |
Large-scale earthquakes pose serious threats to infrastructure causing substantial damage and large residual deformations. Superelastic (SE) Shape-Memory-Alloys (SMAs) are unique alloys with the ability to undergo large deformations, but can recover its original shape upon stress removal. The purpose of this research is to exploit this characteristic of SMAs such that concrete Beam-Column Joints (BCJs) reinforced with SMA bars at the plastic hinge region experience reduced residual deformation at the end of earthquakes. Another objective is to evaluate the seismic performance of SMA Reinforced Concrete BCJs repaired with flowable Structural-Repair-Concrete (SRC). A ¾-scale BCJ reinforced with SMA rebars in the plastic-hinge zone was tested under reversed cyclic loading, and subsequently repaired and retested. The joint was selected from an RC building located in the seismic region of western Canada. It was designed and detailed according to the NBCC 2005 and CSA A23.3-04 recommendations. The behaviour under reversed cyclic loading of the original and repaired joints, their load-storey drift, and energy dissipation ability were compared. The results demonstrate that SMA-RC BCJs are able to recover nearly all of their post-yield deformation, requiring a minimum amount of repair, even after a large earthquake, proving to be smart structural elements. It was also shown that the use of SRC to repair damaged BCJs can restore its full capacity.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001552360
|
oai_dc
|
Monitoring a steel building using GPS sensors
|
Monitoring a steel building using GPS sensors
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Fabio Casciati(University of Pavia); Clemente Fuggini(University of Pavia)"
] |
To assess the performance of a structure requires the measurement of global and relative displacements at critical points across the structure. They should be obtained in real time and in all weather condition. A Global Navigation Satellite System (GNSS) could satisfy the last two requirements. The American Global Position System (GPS) provides long term acquisitions with sampling rates sufficient to track the displacement of long period structures. The accuracy is of the order of sub-centimetres. The steel building which hosts the authors’ laboratory is the reference case-study within this paper. First a comparison of data collected by GPS sensor units with data recorded by tri-axial accelerometers is carried out when dynamic vibrations are induced in the structure by movements of the internal bridge-crane. The elaborations from the GPS position readings are then compared with the results obtained by a Finite Element (FE) numerical simulation. The purposes are: i) to realize a refinement of the structural parameters which characterize the building and ii) to outline a suitable way for processing GPS data toward structural monitoring.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001552361
|
oai_dc
|
A low cost miniature PZT amplifier for wirelessactive structural health monitoring
|
A low cost miniature PZT amplifier for wirelessactive structural health monitoring
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Claudio Olmi(University of Houston); Gangbing Song(University of Houston); Leang-San Shieh(University of Houston); Yi-Lung Mo(University of Houston)"
] |
Piezo-based active structural health monitoring (SHM) requires amplifiers specifically designed for capacitive loads. Moreover, with the increase in number of applications of wireless SHM systems, energy efficiency and cost reduction for this type of amplifiers is becoming a requirement. General lab grade amplifiers are big and costly, and not built for outdoor environments. Although some piezoceramic power amplifiers are available in the market, none of them are specifically targeting the wireless constraints and low power requirements. In this paper, a piezoceramic transducer amplifier for wireless active SHM systems has been designed. Power requirements are met by two digital On/Off switches that set the amplifier in a standby state when not in use. It provides a stable ±180 Volts output with a bandwidth of 7k Hz using a single 12 V battery. Additionally, both voltage and current outputs are provided for feedback control, impedance check, or actuator damage verification. Vibration control tests of an aluminum beam were conducted in the University of Houston lab, while wireless active SHM tests of a wind turbine blade were performed in the Harbin Institute of Technology wind tunnel. The results showed that the developed amplifier provided equivalent results to commercial solutions in suppressing structural vibrations, and that it allows researchers to perform active wireless SHM on moving objects with no power wires from the grid.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001572605
|
oai_dc
|
Antenna sensor skin for fatigue crack detection and monitoring
|
Antenna sensor skin for fatigue crack detection and monitoring
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Srikar Deshmukh(University of Texas at Arlington); Haiying Huang(University of Texas at Arlington); Xiang Xu(University of Texas at Arlington); Irshad Mohammad(University of Texas at Arlington)"
] |
This paper presents a flexible low-profile antenna sensor for fatigue crack detection and monitoring. The sensor was inspired by the sense of pain in bio-systems as a protection mechanism. Because the antenna sensor does not need wiring for power supply or data transmission, it is an ideal candidate as sensing elements for the implementation of engineering sensor skins with a dense sensor distribution. Based on the principle of microstrip patch antenna, the antenna sensor is essentially an electromagnetic cavity that radiates at certain resonant frequencies. By implementing a metallic structure as the ground plane of the antenna sensor, crack development in the metallic structure due to fatigue loading can be detected from the resonant frequency shift of the antenna sensor. A monostatic microwave radar system was developed to interrogate the antenna sensor remotely. Fabrication and characterization of the antenna sensor for crack monitoring as well as the implementation of the remote interrogation system are presented.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001572606
|
oai_dc
|
Biological smart sensing strategies in weakly electric fish
|
Biological smart sensing strategies in weakly electric fish
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Mark E. Nelson(University of Illinois at Urbana-Champaign)"
] |
Biological sensory systems continuously monitor and analyze changes in real-world environments that are relevant to an animal’s specific behavioral needs and goals. Understanding the sensory mechanisms and information processing principles that biological systems utilize for efficient sensory data acquisition may provide useful guidance for the design of smart-sensing systems in engineering applications. Weakly electric fish, which use self-generated electrical energy to actively sense their environment, provide an excellent model system for studying biological principles of sensory data acquisition. The electrosensory system enables these fish to hunt and navigate at night without the use of visual cues. To achieve reliable, real-time task performance, the electrosensory system implements a number of smart sensing strategies, including efficient stimulus encoding, multi-scale virtual sensor arrays, task-dependent filtering and online subtraction of sensory expectation.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001572608
|
oai_dc
|
A wireless impedance analyzer for automated tomographic mapping of a nanoengineered sensing skin
|
A wireless impedance analyzer for automated tomographic mapping of a nanoengineered sensing skin
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Sukhoon Pyo(University of Michigan); Jerome P. Lynch(University of Michigan); Kenneth J. Loh(University of California); Tsung-Chin Hou(National Cheng Kung University(NCKU)); Erik Jarva(University of Michigan)"
] |
Polymeric thin-film assemblies whose bulk electrical conductivity and mechanical performance have been enhanced by single-walled carbon nanotubes are proposed for measuring strain and corrosion activity in metallic structural systems. Similar to the dermatological system found in animals, the proposed self-sensing thin-film assembly supports spatial strain and pH sensing via localized changes in electrical conductivity. Specifically, electrical impedance tomography (EIT) is used to create detailed mappings of film conductivity over its complete surface area using electrical measurements taken at the film boundary. While EIT is a powerful means of mapping the sensing skin’s spatial response, it requires a data acquisition system capable of taking electrical impedance measurements on a large number of electrodes. A low-cost wireless impedance analyzer is proposed to fully automate EIT data acquisition. The key attribute of the device is a flexible sinusoidal waveform generator capable of generating regulated current signals with frequencies from near-DC to 20 MHz. Furthermore, a multiplexed sensing interface offers 32 addressable channels from which voltage measurements can be made. A wireless interface is included to eliminate the cumbersome wiring often required for data acquisition in a structure. The functionality of the wireless impedance analyzer is illustrated on an experimental setup with the system used for automated acquisition of electrical impedance measurements taken on the boundary of a bio-inspired sensing skin recently proposed for structural health monitoring.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001572601
|
oai_dc
|
Microcantilever biosensor: sensing platform, surface characterization and multiscale modeling
|
Microcantilever biosensor: sensing platform, surface characterization and multiscale modeling
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chuin-Shan Chen(National Taiwan University); Shu Kuan(National Taiwan University); Tzu-Hsuan Chang(National Taiwan University); Chia-Ching Chou(National Taiwan University); Shu-Wei Chang(National Taiwan University); Long-Sun Huang(National Taiwan University)"
] |
The microcantilever (MCL) sensor is one of the most promising platforms for next-generation label-free biosensing applications. It outperforms conventional label-free detection methods in terms of portability and parallelization. In this paper, an overview of recent advances in our understanding of the coupling between biomolecular interactions and MCL responses is given. A dual compact optical MCL sensing platform was built to enable biosensing experiments both in gas-phase environments and in solutions. The thermal bimorph effect was found to be an effective nanomanipulator for the MCL platform calibration. The study of the alkanethiol self-assembly monolayer (SAM) chain length effect revealed that 1-octanethiol (C8H17SH) induced a larger deflection than that from 1-dodecanethiol (C12H25SH) in solutions. Using the clinically relevant biomarker Creactive protein (CRP), we revealed that the analytical sensitivity of the MCL reached a diagnostic level of 1~500 μg/ml within a 7% coefficient of variation. Using grazing incident x-ray diffractometer (GIXRD) analysis, we found that the gold surface was dominated by the (111) crystalline plane. Moreover, using X-ray photoelectron spectroscopy (XPS) analysis, we confirmed that the Au-S covalent bonds occurred in SAM adsorption whereas CRP molecular bindings occurred in protein analysis. First principles density functional theory (DFT) simulations were also used to examine biomolecular adsorption mechanisms. Multiscale modeling was then developed to connect the interactions at the molecular level with the MCL mechanical response. The alkanethiol SAM chain length effect in air was successfully predicted using the multiscale scheme.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001572603
|
oai_dc
|
A MEMS/NEMS sensor for human skin temperature measurement
|
A MEMS/NEMS sensor for human skin temperature measurement
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Hongjie Leng(Northeastern University); Yingzi Lin(Northeastern University)"
] |
Human state in human-machine systems highly affects the overall system performance, and should be detected and monitored. Physiological cues are essential indicators of human state and useful for the purpose of monitoring. The study presented in this paper was focused on developing a bio-inspired sensing system, i.e., Nano-Skin, to non-intrusively measure physiological cues on human-machine contact surfaces to detect human state. The paper is presented in three parts. The first part is to analyze the relationship between human state and physiological cues, and to introduce the conceptual design of Nano-Skin. Generally, heart rate, skin conductance, skin temperature, operating force, blood alcohol concentration, sweat rate, and electromyography are closely related with human state. They can be measured through human-machine contact surfaces using Nano-Skin. The second part is to discuss the technologies for skin temperature measurement.
The third part is to introduce the design and manufacture of the Nano-Skin for skin temperature measurement. Experiments were performed to verify the performance of the Nano-Skin in temperature measurement. Overall, the study concludes that Nano-Skin is a promising product for measuring physiological cues on human-machine contact surfaces to detect human state.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001572607
|
oai_dc
|
Implementation of a bio-inspired two-mode structural health monitoring system
|
Implementation of a bio-inspired two-mode structural health monitoring system
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Tzu-Kang Lin(National Center for Research on Earthquake Engineering); Li-Chen Yu(National Taiwan University); Kuo-Chun Chang(National Taiwan University); Anne Kiremidjian(Stanford University); Chang-Hung Ku(National Taiwan University)"
] |
A bio-inspired two-mode structural health monitoring (SHM) system based on the Naïve Bayes (NB) classification method is discussed in this paper. To implement the molecular biology based Deoxyribonucleic acid (DNA) array concept in structural health monitoring, which has been demonstrated to be superior in disease detection, two types of array expression data have been proposed for the development of the SHM algorithm. For the micro-vibration mode, a two-tier auto-regression with exogenous (AR-ARX)process is used to extract the expression array from the recorded structural time history while an ARX process is applied for the analysis of the earthquake mode. The health condition of the structure is then determined using the NB classification method. In addition, the union concept in probability is used to improve the accuracy of the system. To verify the performance and reliability of the SHM algorithm, a downscaled eight-storey steel building located at the shaking table of the National Center for Research on Earthquake Engineering (NCREE) was used as the benchmark structure. The structural response from different damage levels and locations was collected and incorporated in the database to aid the structural health monitoring process. Preliminary verification has demonstrated that the structure health condition can be precisely detected by the proposed algorithm. To implement the developed SHM system in a practical application, a SHM prototype consisting of the input sensing module, the transmission module, and the SHM platform was developed. The vibration data were first measured by the deployed sensor, and subsequently the SHM mode corresponding to the desired excitation is chosen automatically to quickly evaluate the health condition of the structure. Test results from the ambient vibration and shaking table test showed that the condition and location of the benchmark structure damage can be successfully detected by the proposed SHM prototype system, and the information is instantaneously transmitted to a remote server to facilitate real-time monitoring. Implementing the bio-inspired two-mode SHM practically has been successfully demonstrated.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001572600
|
oai_dc
|
Bio-inspired leaf stent for direct treatment of cerebral aneurysms: design and finite element analysis
|
Bio-inspired leaf stent for direct treatment of cerebral aneurysms: design and finite element analysis
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Xiang Zhou(University of Oxford); Zhong You(University of Oxford); James Byrne, M.D.(University of Oxford)"
] |
Cerebral aneurysm is common lesion among adult population. Current methods for treating the disease have several limitations. Inspired by fern leaves, we have developed a new stent, called leaf stent, which can provide a tailored coverage at the neck of an aneurysm and thus prevent the blood from entering the aneurysm. It alone can be used to treat the cerebral aneurysm and therefore overcomes problems existing in current treating methods. The paper focuses on the numerical simulation of the leaf stents. The mechanical behaviour of the stent in various designs has been investigated using the finite element method. It has been found that certain designs provide adequate radial force and have excellent longitudinal flexibility. The performance of certain leaf stents is comparable and even superior to those of the commercially available cerebral stents such as the Neuroform stent and the Enterprise stent, commonly used for stent assisted coiling, while at the same time, providing sufficient coverage to isolate the aneurysm without using coils.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001572602
|
oai_dc
|
Controlling a lamprey-based robot with an electronic nervous system
|
Controlling a lamprey-based robot with an electronic nervous system
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"A Westphal(Northeastern University); J Ayers(Northeastern University); N.F. Rulkov(Information Systems Laboratories,Institute for Nonlinear Science); D Brady(Northeastern University); M Hunt(Ariel Inc.)"
] |
We are developing a biomimetic robot based on the Sea Lamprey. The robot consists of a cylindrical electronics bay propelled by an undulatory body axis. Shape memory alloy (SMA) actuators generate propagating flexion waves in five undulatory segments of a polyurethane strip. The behavior of the robot is controlled by an electronic nervous system (ENS) composed of networks of discrete-time map-based neurons and synapses that execute on a digital signal processing chip. Motor neuron action potentials gate power transistors that apply current to the SMA actuators. The ENS consists of a set of segmental central pattern generators (CPGs), modulated by layered command and coordinating neuron networks, that integrate input from exteroceptive sensors including a compass, accelerometers, inclinometers and a short baseline sonar array (SBA). The CPGs instantiate the 3-element hemi-segmental network model established from physiological studies. Anterior and posterior propagating pathways between CPGs mediate intersegmental coordination to generate flexion waves for forward and backward swimming. The command network mediates layered exteroceptive reflexes for homing, primary orientation, and impediment compensation. The SBA allows homing on a sonar beacon by indicating deviations in azimuth and inclination. Inclinometers actuate a bending segment between the hull and undulator to allow climb and dive. Accelerometers can distinguish collisions from impediment to allow compensatory reflexes. Modulatory commands mediate speed control and turning. A SBA communications interface is being developed to allow supervised reactive autonomy.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001572604
|
oai_dc
|
Emergent damage pattern recognition using immune network theory
|
Emergent damage pattern recognition using immune network theory
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Bo Chen(Michigan Technological University); Chuanzhi Zang(Michigan Technological University)"
] |
This paper presents an emergent pattern recognition approach based on the immune network theory and hierarchical clustering algorithms. The immune network allows its components to change and learn patterns by changing the strength of connections between individual components. The presented immunenetwork- based approach achieves emergent pattern recognition by dynamically generating an internal image for the input data patterns. The members (feature vectors for each data pattern) of the internal image are produced by an immune network model to form a network of antibody memory cells. To classify antibody memory cells to different data patterns, hierarchical clustering algorithms are used to create an antibody memory cell clustering. In addition, evaluation graphs and L method are used to determine the best number of clusters for the antibody memory cell clustering. The presented immune-network-based emergent pattern recognition (INEPR) algorithm can automatically generate an internal image mapping to the input data patterns without the need of specifying the number of patterns in advance. The INEPR algorithm has been tested using a benchmark civil structure. The test results show that the INEPR algorithm is able to recognize new structural damage patterns.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001602425
|
oai_dc
|
In situ reduction of gold nanoparticles in PDMS matrices and applications for large strain sensing
|
In situ reduction of gold nanoparticles in PDMS matrices and applications for large strain sensing
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Donghyeon Ryu(University of California); Kenneth J. Loh(University of California); Robert Ireland(University of California); Mohammad Karimzada(University of California); Frank Yaghmaie(University of California); Andrea M. Gusman(University of California)"
] |
Various types of strain sensors have been developed and widely used in the field for monitoring the mechanical deformation of structures. However, conventional strain sensors are not suited for measuring large strains associated with impact damage and local crack propagation. In addition, strain sensors are resistive-type transducers, which mean that the sensors require an external electrical or power source. In this study, a gold nanoparticle (GNP)-based polymer composite is proposed for large strain sensing. Fabrication of the composites relies on a novel and simple in situ GNP reduction technique that is performed directly within the elastomeric poly(dimethyl siloxane) (PDMS) matrix. First, the reducing and stabilizing capacities of PDMS constituents and mixtures are evaluated via visual observation, ultraviolet-visible (UV-Vis) spectroscopy, and transmission electron microscopy. The large strain sensing capacity of the GNP-PDMS thin film is then validated by correlating changes in thin film optical properties (e.g., maximum UV-Vis light absorption) with applied tensile strains. Also, the composite’s strain sensing performance (e.g., sensitivity and sensing range) is also characterized with respect to gold chloride concentrations within the PDMS mixture.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001602428
|
oai_dc
|
Parametric resonance of axisymmetric sandwich annular plate with ER core layer and constraining layer
|
Parametric resonance of axisymmetric sandwich annular plate with ER core layer and constraining layer
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jia-Yi Yeh(Chung Hwa University of Medical Technology)"
] |
The parametric resonance problems of axisymmetric sandwich annular plate with an electrorheological (ER) fluid core and constraining layer are investigated. The annular plate is covered an electrorheological fluid core layer and a constraining layer to improve the stability of the system. The discrete layer annular finite element and the harmonic balance method are adopted to calculate the boundary of instability regions for the sandwich annular plate system. Besides, the rheological property of an electrorheological material, such as viscosity, plasticity, and elasticity can be changed when applying an electric field. When the electric field is applied on the sandwich structure, the damping of the sandwich system is more effective. Thus, variations of the instability regions for the sandwich annular plate with different applying electric fields, thickness of ER layer, and some designed parameters are presented and discussed in this study. The ER fluid core is found to have a significant effect on the location of the boundaries of the instability regions.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001602429
|
oai_dc
|
Experiment of an ABS-type control strategy for semi-active friction isolation systems
|
Experiment of an ABS-type control strategy for semi-active friction isolation systems
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Lyan-Ywan Lu(National Kaohsiung First University of Science and Technology); Ging-Long Lin(National Chung Hsing University); Chen-Yu Lin(National Center for Research on Earthquake Engineering)"
] |
Recent studies have discovered that a conventional passive isolation system may suffer from an excessive isolator displacement when subjected to a near-fault earthquake that usually has a long-period velocity pulse waveform. Semi-active isolation using variable friction dampers (VFD), which requires a suitable control law, may provide a solution to this problem. To control the VFD in a semi-active isolation system more efficiently, this paper investigates experimentally the possible use of a control law whose control logic is similar to that of the anti-lock braking systems (ABS) widely used in the automobile industry. This ABS-type controller has the advantages of being simple and easily implemented, because it only requires the measurement of the isolation-layer velocity and does not require system modeling for gain design. Most importantly, it does not interfere with the isolation period, which usually decides the isolation efficiency. In order to verify its feasibility and effectiveness, the ABS-type controller was implemented on a variable-friction isolation system whose slip force is regulated by an embedded piezoelectric actuator, and a seismic simulation test was conducted for this isolation system. The experimental results demonstrate that, as compared to a passive isolation system with various levels of added damping, the semi-active isolation system using the ABS-type controller has the better overall performance when both the far-field and the near-fault earthquakes with different PGA levels are considered.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001602417
|
oai_dc
|
Non linear analysis of a functionally graded square plate with two smart layers as sensor and actuator under normal pressure
|
Non linear analysis of a functionally graded square plate with two smart layers as sensor and actuator under normal pressure
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"M. Arefi(Tarbiat Modares University); G.H. Rahimi(Tarbiat Modares University)"
] |
The present paper addresses the nonlinear response of a FG square plate with two smart layers as a sensor and actuator under pressure. Geometric nonlinearity was considered in the strain-displacement relation based on the Von-Karman assumption. All the mechanical and electrical properties except Poisson’s ratio can vary continuously along the thickness of the plate based on a power function. Electric potential was assumed as a quadratic function along the thickness direction and trigonometric function along the planar coordinate. By evaluating the mechanical and electrical energy, the total energy equation can be minimized with respect to amplitude of displacements and electrical potential. The effect of non homogenous index was investigated on the responses of the system. Obtained results indicate that with increasing the non homogenous index, the displacements and electric potential tend to an asymptotic value. Displacements and electric potential can be presented in terms of planar coordinate system. A linear analysis was employed and then the achieved results are compared with those results that are obtained using the nonlinear analysis. The effect of the geometric nonlinearity is investigated by using the comparison between the linear and nonlinear results. Displacementload and potential-load curves verified the necessity of a nonlinear analysis rather than a linear analysis. Improvement of the previous results (by the linear analysis) through employing a nonlinear analysis can be presented as novelty of this study.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001602421
|
oai_dc
|
Influence of time delay and saturation capacity to the response of controlled structures under earthquake excitations
|
Influence of time delay and saturation capacity to the response of controlled structures under earthquake excitations
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Nikos G. Pnevmatikos(National Technical University of Athens); Charis J. Gantes(National Technical University of Athens)"
] |
During the last thirty years many structural control concepts have been proposed for the reduction of the structural response caused by earthquake excitations. Their research and implementation in practice have shown that seismic control of structures has a lot of potential but also many limitations. In this paper the importance of two practical issues, time delay and saturation effect, on the performance of controlled structures, is discussed. Their influence, both separately and in interaction, on the response of structures controlled by a modified pole placement algorithm is investigated. Characteristic buildings controlled by this algorithm and subjected to dynamic loads, such as harmonic signals and actual seismic events, are analyzed for a range of levels of time delay and saturation capacity of the control devices. The response reduction surfaces for the combined influence of time delay and force saturation of the controlled buildings are obtained.
Conclusions regarding the choice of the control system and the desired properties of the control devices are drawn.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001642346
|
oai_dc
|
Statistics and probability analysis of vehicle overloads on a rigid frame bridge from long-term monitored strains
|
Statistics and probability analysis of vehicle overloads on a rigid frame bridge from long-term monitored strains
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Liqun Tang(South China University of Technology); Yinghua Li(South China University of Technology); Zejia Liu(South China University of Technology); Yiping Liu(South China University of Technology)"
] |
It is well known that overloaded vehicles may cause severe damages to bridges, and how to estimate and evaluate the status of the overloaded vehicles passing through bridges become a challenging problem. Therefore, based on the monitored strain data from a structural health monitoring system (SHM) installed on a bridge, a method is recommended to identify and analyze the probability of overloaded vehicles. Overloaded vehicle loads can cause abnormity in the monitored strains, though the abnormal strains may be small in a concrete continuous rigid frame bridge. Firstly, the abnormal strains are identified from the abundant strains in time sequence by taking the advantage of wavelet transform in abnormal signal identification;secondly, the abnormal strains induced by heavy vehicles are picked up by the comparison between the identified abnormal strains and the strain threshold gotten by finite element analysis of the normal heavy vehicle; finally, according to the determined abnormal strains induced by overloaded vehicles, the statistics of the overloaded vehicles passing through the bridge are summarized and the whole probability of the overloaded vehicles is analyzed. The research shows the feasibility of using the monitored strains from a longterm SHM to identify the information of overloaded vehicles passing through a bridge, which can help the traffic department to master the heavy truck information and do the damage analysis of bridges further.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001642343
|
oai_dc
|
Seismic damage detection of a reinforced concrete structure by finite element model updating
|
Seismic damage detection of a reinforced concrete structure by finite element model updating
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"유은종(한양대학교); 정란(단국대학교)"
] |
Finite element (FE) model updating is a useful tool for global damage detection technique, which identifies the damage of the structure using measured vibration data. This paper presents the application of a finite element model updating method to detect the damage of a small-scale reinforced concrete building structure using measured acceleration data from shaking table tests. An iterative FE model updating strategy using the least-squares solution based on sensitivity of frequency response functions and natural frequencies was provided. In addition, a side constraint to mitigate numerical difficulties associated with ill-conditioning was described. The test structure was subjected to six El Centro 1942 ground motion histories with different Peak Ground Accelerations (PGA) ranging from 0.06 g to 0.5 g, and analytical models corresponding to each stage of the shaking were obtained using the model updating method. Flexural stiffness values of the structural members were chosen as the updating parameters. In model updating at each stage of shaking, the initial values of the parameter were set to those obtained from the previous stage. Severity of damage at each stage of shaking was determined from the change of the updated stiffness values. Results indicated that larger reductions in stiffness values occurred at the slab members than at the wall members, and this was consistent with the observed damage pattern of the test structure.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001642341
|
oai_dc
|
Seismic and vibration tests for assessing the effectiveness of GFRP for retrofitting masonry structures
|
Seismic and vibration tests for assessing the effectiveness of GFRP for retrofitting masonry structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Costas Papadimitriou(University of Thessaly); Paul Michelis(Institute of Mechanics of Material & Geostructures S.A.); Grigoris K. Karaiskos(University of Thessaly); Dimitra-Christina Papadioti(University of Thessaly); Clemente Fuggini(D'Appolonia S.p.A.)"
] |
Full-scale shake table seismic experiments and low-amplitude vibration tests on a masonry building are carried out to assess its seismic performance as well as study the effectiveness of a new multifunctional textile material for retrofitting masonry structures against earthquakes. The un-reinforced and the retrofitted with glass fiber reinforced polymer (GFRP) strips masonry building was subjected to a series of earthquake excitations of increasing magnitude in order to progressively induce various small, moderate and severe levels of damage to the masonry walls. The performance of the original and retrofitted building states is evaluated. Changes in the dynamic characteristics (lowest four modal frequencies and damping ratios) of the building are used to assess and quantify the damage states of the masonry walls. For this, the dynamic modal characteristics of the structure states after each earthquake event were estimated by performing low-amplitude impulse hammer and sine-sweep forced vibration tests. Comparisons between the modal results calculated using traditional accelerometers and those using Fiber Bragg Grating (FBG) sensors embedded in the reinforcing textile were carried on to investigate the reliability and accuracy of FBG sensors in tracking the dynamic behaviour of the building. The retrofitting actions restored the stiffness characteristics of the reinforced masonry structure to the levels of the original undamaged un-reinforced structure. The results show that despite a similar dynamic behavior identified, corresponding to reduction of the modal frequencies, the unreinforced masonry building was severely damaged, while the reinforced masonry building was able to withstand, without visual damage, the induced strong seismic excitations. The applied GFRP reinforcement architecture for one storey buildings was experimentally proven reliable for the most severe earthquake accelerations. It was easily placed in a short time and it is a cost effective solution (covering only 20% of the external wall surfaces) when compared to the cost for full wall coverage by GFRPs.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001642344
|
oai_dc
|
Incremental displacement estimation of structures using paired structured light
|
Incremental displacement estimation of structures using paired structured light
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"명현(한국과학기술원); Haemin Jeon(KAIST); Jae-Uk Shin(KAIST)"
] |
As civil structures are exposed to various external loads, it is essential to assess the structural condition, especially the structural displacement, in every moment. Therefore, a visually servoed paired structured light system was proposed in the previous study. The proposed system is composed of two screens facing with each other, each with a camera, a screen, and one or two lasers controlled by a 2-DOF manipulator. The 6-DOF displacement can be calculated from the positions of three projected laser beams and the rotation angles of the manipulators. In the estimation process, one of well-known iterative methods such as Newton-Raphson or extended Kalman filter (EKF) was used for each measurement. Although the proposed system with the aforementioned algorithms estimates the displacement with high accuracy, it takes relatively long computation time. Therefore, an incremental displacement estimation (IDE) algorithm which updates the previously estimated displacement based on the difference between the previous and the current observed data is newly proposed. To validate the performance of the proposed algorithm, simulations and experiments are performed. The results show that the proposed algorithm significantly reduces the computation time with the same level of accuracy compared to the EKF with multiple iterations.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001642342
|
oai_dc
|
Stochastic optimal control analysis of a piezoelectric shell subjected to stochastic boundary perturbations
|
Stochastic optimal control analysis of a piezoelectric shell subjected to stochastic boundary perturbations
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Z.G. Ying(Zhejiang University); J. Feng(Zhejiang University); W.Q. Zhu(Zhejiang University); Y.Q. Ni(The Hong Kong Polytechnic University)"
] |
The stochastic optimal control for a piezoelectric spherically symmetric shell subjected to stochastic boundary perturbations is constructed, analyzed and evaluated. The stochastic optimal control problem on the boundary stress output reduction of the piezoelectric shell subjected to stochastic boundary displacement perturbations is presented. The electric potential integral as a function of displacement is obtained to convert the differential equations for the piezoelectric shell with electrical and mechanical coupling into the equation only for displacement. The displacement transformation is constructed to convert the stochastic boundary conditions into homogeneous ones, and the transformed displacement is expanded in space to convert further the partial differential equation for displacement into ordinary differential equations by using the Galerkin method. Then the stochastic optimal control problem of the piezoelectric shell in partial differential equations is transformed into that of the multi-degree-of-freedom system. The optimal control law for electric potential is determined according to the stochastic dynamical programming principle. The frequency-response function matrix, power spectral density matrix and correlation function matrix of the controlled system response are derived based on the theory of random vibration. The expressions of mean-square stress, displacement and electric potential of the controlled piezoelectric shell are finally obtained to evaluate the control effectiveness. Numerical results are given to illustrate the high relative reduction in the root-mean-square boundary stress of the piezoelectric shell subjected to stochastic boundary displacement perturbations by the optimal electric potential control.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001584880
|
oai_dc
|
Seismic response control of elastic and inelastic structures by using passive and semi-active tuned mass dampers
|
Seismic response control of elastic and inelastic structures by using passive and semi-active tuned mass dampers
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"우성식(단국대학교); 이상현(단국대학교); 정란(단국대학교)"
] |
In this study, the performances of a passive tuned mass damper (TMD) and a semi-active TMD (STMD) were evaluated in terms of seismic response control of elastic and inelastic structures under seismic loads. First, elastic displacement spectra were obtained for damped structures with a passive TMD and with a STMD proposed in this study. The displacement spectra confirmed that the STMD provided much better control performance than passive TMD and the STMD had less stroke requirement. Also, the robustness of the TMD was evaluated by off-tuning the frequency of the TMD to that of the structure. Finally, numerical analyses were conducted for an inelastic structure of hysteresis described by the Bouc-Wen model. The results indicated that the performance of the passive TMD whose design parameters were optimized for an elastic structure considerably deteriorated when the hysteretic portion of the structural responses increased, and that the STMD showed about 15-40% more response reduction than the TMD.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001584886
|
oai_dc
|
Using harmonic class loading for damage identification of plates by wavelet transformation approach
|
Using harmonic class loading for damage identification of plates by wavelet transformation approach
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"S.B. Beheshti-Aval(K.N.Toosi University of Technology); M. Taherinasab(K.N.Toosi University of Technology); M. Noori(California Polytechnic State University)"
] |
In this paper, the harmonic displacement response of a damaged square plate with all-over partthrough damage parallel to one edge is utilized as the input signal function in wavelet analysis. The method requires the properties of the damaged plate, i.e., no information about the original undamaged structure is required. The location of damage is identified by sudden changes in the spatial variation of transformed response. The incurred damage causes a change in the stiffness or mass of the plate. This causes a localized singularity which can be identified by a wavelet analysis of the displacement response. In this study via numerical examples shown by using harmonic response is more versatile and effective compared with the static deflection response, specially in the presence of noise. In the light of the obtained results, suggestions for future work are presented and discussed.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001584896
|
oai_dc
|
A phase synthesis time reversal impact imaging method for on-line composite structure monitoring
|
A phase synthesis time reversal impact imaging method for on-line composite structure monitoring
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Lei Qiu(Nanjing University of Aeronautics and Astronautics); Shenfang Yuan(Nanjing University of Aeronautics and Astronautics)"
] |
Comparing to active damage monitoring, impact localization on composite by using time reversal focusing method has several difficulties. First, the transfer function of the actuator-sensor path is difficult to be obtained because of the limitation that no impact experiment is permitted to perform on the real structure and the difficulty to model it because the performance of real aircraft composite is much more complicated comparing to metal structure. Second, the position of impact is unknown and can not be controlled as the excitation signal used in the active monitoring. This makes it not applicable to compare the difference between the excitation and the focused signal. Another difficulty is that impact signal is frequency broadband, giving rise to the difficulty to process virtual synthesis because of the highly dispersion nature of frequency broadband Lamb wave in plate-like structure. Aiming at developing a practical method for on-line localization of impact on aircraft composite structure which can take advantage of time reversal focusing and does not rely on the transfer function, a PZT sensor array based phase synthesis time reversal impact imaging method is proposed. The complex Shannon wavelet transform is presented to extract the frequency narrow-band signals from the impact responded signals of PZT sensors. A phase synthesis process of the frequency narrow-band signals is implemented to search the time reversal focusing position on the structure which represents the impact position. Evaluation experiments on a carbon fiber composite structure show that the proposed method realizes the impact imaging and localization with an error less than 1.5 cm. Discussion of the influence of velocity errors and measurement noise is also given in detail.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001584903
|
oai_dc
|
Frequency characteristic analysis on acoustic emission of mortar using cement-based piezoelectric sensors
|
Frequency characteristic analysis on acoustic emission of mortar using cement-based piezoelectric sensors
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Youyuan Lu(Hong Kong University of Science and Technology); Zongjin Li(Hong Kong University of Science and Technology)"
] |
Acoustic emission (AE) monitoring was conducted for mortar specimens under three types of static loading patterns (cubic-splitting, direct-shear and pull-out). Each of the applied loading patterns was expected to produce a particular fracture process. Subsequently, the AEs generated by various fracture or damage processes carried specific information on temporal micro-crack behaviors of concrete for post analysis, which was represented in the form of detected AE signal characteristics. Among various available characteristics of acquired AE signals, frequency content was of great interest. In this study, cement-based piezoelectric sensor (as AE transducer) and home-programmed DEcLIN monitoring system were utilized for AE monitoring on mortar. The cement-based piezoelectric sensor demonstrated enhanced sensitivity and broad frequency domain response range after being embedded into mortar specimens. This broad band characteristic of cement-based piezoelectric sensor in frequency domain response benefited the analysis of frequency content of AE. Various evaluation methods were introduced and employed to clarify the variation characteristics of AE frequency content in each test. It was found that the variation behaviors of AE frequency content exhibited a close relationship with the applied loading processes during the tests.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001584891
|
oai_dc
|
Mathematical modeling of actively controlled piezo smart structures: a review
|
Mathematical modeling of actively controlled piezo smart structures: a review
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Vivek Gupta(Himachal Pradesh University); Manu Sharma(UIET, Panjab University); Nagesh Thakur(Himachal Pradesh University)"
] |
This is a review paper on mathematical modeling of actively controlled piezo smart structures. Paper has four sections to discuss the techniques to: (i) write the equations of motion (ii) implement sensoractuator design (iii) model real life environmental effects and, (iv) control structural vibrations. In section (i), methods of writing equations of motion using equilibrium relations, Hamilton’s principle, finite element technique and modal testing are discussed. In section (ii), self-sensing actuators, extension-bending actuators,shear actuators and modal sensors/actuators are discussed. In section (iii), modeling of thermal, hygro and other non-linear effects is discussed. Finally in section (iv), various vibration control techniques and useful software are mentioned. This review has two objectives: (i) practicing engineers can pick the most suitable philosophy for their end application and, (ii) researchers can come to know how the field has evolved, how it can be extended to real life structures and what the potential gaps in the literature are.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001627170
|
oai_dc
|
Damage detection from the variation of parameter matrices estimated by incomplete FRF data
|
Damage detection from the variation of parameter matrices estimated by incomplete FRF data
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Salam Rahmatalla(University of Iowa); 은희창(강원대학교); 이은택(중앙대학교)"
] |
It is not easy to experimentally obtain the FRF (Frequency Response Function) matrix corresponding to a full set of DOFs (degrees of freedom) for a dynamic system. Utilizing FRF data measured at specific positions, with DOFs less than that of the system, as constraints to describe a damaged system, this study identifies parameter matrices such as mass, stiffness and damping matrices of the system, and provides a damage identification method from their variations. The proposed parameter identification method is compared to Lee and Kim’s method and Fritzen’s method. The validity of the proposed damage identification method is illustrated in a simple dynamic system.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001627166
|
oai_dc
|
Damage localization in plate-like structure using built-in PZT sensor network
|
Damage localization in plate-like structure using built-in PZT sensor network
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Xinglong Liu(CSR Qingdao Sifang, Co., Ltd,); Chengxu Zhou(Yamaguchi University); Zhongwei Jiang(Yamaguchi University)"
] |
In this study, a Lamb-wave based damage detection approach is proposed for damage localization in plate. A sensor network consisting of three PZT wafer type actuators/sensors is used to generate and detect Lamb waves. To minimize the complication resulted from the multimode and dispersive characteristics of Lamb waves, the fundamental symmetric Lamb mode, S0 is selectively generated through designing the excitation frequency of the narrowband input signal. A damage localization algorithm based upon the configuration of the PZT sensor network is developed. Time-frequency analysis method is applied to purify the raw signal and extract damage features. Experimental result obtained from aluminum plate verified the proposed damage localization approach.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001627173
|
oai_dc
|
Experimental study on the vibration mitigation of offshore tension leg platform system with UWTLCD
|
Experimental study on the vibration mitigation of offshore tension leg platform system with UWTLCD
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Hsien Hua Lee(National Sun Yat-sen University); H.H. Juang(National Sun Yat-sen University)"
] |
In this research, a typical tension-leg type of floating platform incorporated with an innovative concept of underwater tuned liquid column damper system (UWTLCD) is studied. The purpose of this study is to improve the structural safety by means of mitigating the wave induced vibrations and stresses on the offshore floating Tension Leg Platform (TLP) system. Based on some encouraging results from a previous study, where a Tuned Liquid Column Damper (TLCD) system was employed in a floating platform system to reduce the vibration of the main structure, in this study, the traditional TLCD system was modified and tested. Firstly, the orifice-tube was replaced with a smaller horizontal tube and secondly, the TLCD system was combined into the pontoon system under the platform. The modification creates a multipurpose pontoon system associated with vibration mitigation function. On the other hand, the UWTLCD that is installed underwater instead would not occupy any additional space on the platform and yet provide buoyancy to the system. Experimental tests were performed for the mitigation effect and parameters besides the wave conditions, such as pontoon draught and liquid-length in the TLCD were taken into account in the test. It is found that the accurately tuned UWTLCD system could effectively reduce the dynamic response of the offshore platform system in terms of both the vibration amplitude and tensile forces measured in the mooring tethers.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001627159
|
oai_dc
|
Influence line- model correction approach for the assessment of engineering structures using novel monitoring techniques
|
Influence line- model correction approach for the assessment of engineering structures using novel monitoring techniques
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Alfred Strauss(University of Natural Resources and Life Sciences); Roman Wendner(University of Natural Resources and Life Sciences); Dan M. Frangopol(Lehigh Univ.); Konrad Bergmeister(University of Natural Resources and Life Sciences)"
] |
In bridge engineering, maintenance strategies and thus budgetary demands are highly influenced by construction type and quality of design. Nowadays bridge owners and planners tend to include life-cycle cost analyses in their decision processes regarding the overall design trying to optimize structural reliability and durability within financial constraints. Smart permanent and short term monitoring can reduce the associated risk of new design concepts by observing the performance of structural components during prescribed time periods. The objectives of this paper are the discussion and analysis of influence line or influence field approaches in terms of (a) an efficient incorporation of monitoring information in the structural performance assessment, (b) an efficient characterization of performance indicators for the assessment of structures, (c) the ability of optimizing the positions of sensors of a monitoring system, and (d) the ability of checking the robustness of the monitoring systems applied to a structure. The proposed influence line- model correction approach has been applied to an integrative monitoring system that has been installed for the performance assessment of an existing three-span jointless bridge.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001627168
|
oai_dc
|
Vibration mitigation of stay cable using optimally tuned MR damper
|
Vibration mitigation of stay cable using optimally tuned MR damper
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Hongwei Huang(Tongji University); Limin Sun(Tongji University); Xiaolu Jiang(Shanghai Urban Construction Design & Research Institute)"
] |
Mechanical dampers have been proved to be one of the most effective countermeasures for vibration mitigation of stay cables in various cable-stayed bridges over the world. However, for long stay cables, as the installation height of the damper is restricted due to the aesthetic concern, using passive dampers alone may not satisfy the control requirement of the stay cables. In this connection, semi-active MR dampers have been proposed for the vibration mitigation of long stay cables. Although various studies have been carried out on the implementation of MR dampers on stay cables, the optimal damping performance of the cable-MR damper system has yet to be evaluated. Therefore, this paper aims to investigate the effectiveness of MR damper as a semi-active control device for the vibration mitigation of stay cable. The mathematical model of the MR damper will first be established through a performance test. Then, an efficient semi-active control strategy will be derived, where the damping of MR damper will be tuned according to the dynamic characteristics of stay cable, in order to achieve optimal damping of cable-damper system. Simulation study will be carried out to verify the proposed semi-active control algorithm for suppressing the cable vibrations induced by different loading patterns using optimally tuned MR damper. Finally, the effectiveness of MR damper in mitigating multi modes of cable vibration will be examined theoretically
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001595803
|
oai_dc
|
Health monitoring of reinforced concrete slabs subjected to earthquake-type dynamic loading via measurement and analysis of acoustic emission signals
|
Health monitoring of reinforced concrete slabs subjected to earthquake-type dynamic loading via measurement and analysis of acoustic emission signals
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Antolino Gallego(University of Granada); Amadeo Benavent-Climent(University of Granada); Cristóbal Infantes(University of Granada)"
] |
This paper discusses the applicability of Acoustic Emission (AE) to assess the damage in reinforced concrete (RC) structures subjected to complex dynamic loadings such as those induced by earthquakes. The AE signals recorded during this type of event can be complicated due to the arbitrary and random nature of seismicity and the fact that the signals are highly contaminated by many spurious sources of noise. This paper demonstrates that by properly filtering the AE signals, a very good correlation can be found between AE and damage on the RC structure. The basic experimental data used for this research are the results of fourteen seismic simulations conducted with a shake table on an RC slab supported on four steel columns. The AE signals were recorded by several low-frequency piezoelectric sensors located on the bottom surface of the slab. The evolution of damage under increasing values of peak acceleration applied to the shake table was monitored in terms of AE and dissipated plastic strain energy. A strong correlation was found between the energy dissipated by the concrete through plastic deformations and the AE energy calculated after properly filtering the signals. For this reason, a procedure is proposed to analyze the AE measured in a RC structure during a seismic event so that it can be used for damage assessment.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001595806
|
oai_dc
|
Exact solutions of the piezoelectric transducer under multi loads
|
Exact solutions of the piezoelectric transducer under multi loads
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Zhang Taotao(Beihang University); Shi Zhifei(Beijing Jiaotong University)"
] |
Under the external shearing stress, the external radial stress and the electric potential simultaneously, the piezoelectric hollow cylinder transducer is studied. With the Airy stress function method, the analytical solutions of this transducer are obtained based on the theory of piezo-elasticity. The solutions are compared with the finite element results of Ansys and a good agreement is found. Inherent properties of this piezoelectric cylinder transducer are presented and discussed. It is very helpful for the design of the bearing controllers.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001595804
|
oai_dc
|
Energy-balance assessment of shape memory alloy-based seismic isolation devices
|
Energy-balance assessment of shape memory alloy-based seismic isolation devices
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"O.E. Ozbulut(Texas A&M University); S. Hurlebaus(Texas A&M University)"
] |
This study compares the performance of two smart isolation systems that utilize superelastic shape memory alloys (SMAs) for seismic protection of bridges using energy balance concepts. The first isolation system is a SMA/rubber-based isolation system (SRB-IS) and consists of a laminated rubber bearing that decouples the superstructure from the bridge piers and a SMA device that provides additional energy dissipation and re-centering capacity. The second isolation system, named as superelastic-friction base isolator (S-FBI), combines the superelastic SMAs with a flat steel-Teflon bearing rather than a laminated rubber bearing. Seismic energy equations of a bridge structure with SMA-based isolation systems are established by absolute and relative energy balance formulations. Nonlinear time history analyses are performed in order to assess the effectiveness of the isolation systems and to compare their performance. The program RSPMatch 2005 is employed to generate spectrum compatible ground motions that are used in time history analyses of the isolated bridge. Results indicate that SRB-IS produces higher seismic input energy, recoverable energy and base shears as compared to the S-FBI system. Also, it is shown that combining superelastic SMAs with a sliding bearing rather than rubber bearing significantly reduce the amount of the required SMA material.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001595802
|
oai_dc
|
Design and implementation of fast output sampling feedback control for shape memory alloy actuated structures
|
Design and implementation of fast output sampling feedback control for shape memory alloy actuated structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"K. Dhanalakshmi(National Institute of Technology); M. Umapathy(National Institute of Technology); D. Ezhilarasi(National Institute of Technology); B. Bandyopadhyay(Indian Institute of Technology Bombay)"
] |
This paper presents the design and experimental evaluation of fast output sampling feedback controller to minimize structural vibration of a cantilever beam using Shape Memory Alloy (SMA) wires as control actuators and piezoceramics as sensor and disturbance actuator. Linear dynamic models of the smart cantilever beam are obtained using online recursive least square parameter estimation. A digital control system that consists of Simulink modeling software and dSPACE DS1104 controller board is used for identification and control. The effectiveness of the controller is shown through simulation and experimentation by exciting the structure at resonance.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001595800
|
oai_dc
|
Structural parameter estimation combining domain decomposition techniques with immune algorithm
|
Structural parameter estimation combining domain decomposition techniques with immune algorithm
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"A. Rama Mohan Rao(CSIR-Structural Engineering Research Centre); K. Lakshmi(CSIR-Structural Engineering Research Centre)"
] |
Structural system identification (SSI) is an inverse problem of difficult solution. Currently, difficulties lie in the development of algorithms which can cater to large size problems. In this paper, a parameter estimation technique based on evolutionary strategy is presented to overcome some of the difficulties encountered in using the traditional system identification methods in terms of convergence. In this paper, a non-traditional form of system identification technique employing evolutionary algorithms is proposed. In order to improve the convergence characteristics, it is proposed to employ immune algorithms which are proved to be built with superior diversification mechanism than the conventional evolutionary algorithms and are being used for several practical complex optimisation problems. In order to reduce the number of design variables, domain decomposition methods are used, where the identification process of the entire structure is carried out in multiple stages rather than in single step. The domain decomposition based methods also help in limiting the number of sensors to be employed during dynamic testing of the structure to be identified, as the process of system identification is carried out in multiple stages. A fifteen storey framed structure, truss bridge and 40 m tall microwave tower are considered as a numerical examples to demonstrate the effectiveness of the domain decomposition based structural system identification technique using immune algorithm.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001471095
|
oai_dc
|
Vibration isolation with smart fluid dampers: a benchmarking study
|
Vibration isolation with smart fluid dampers: a benchmarking study
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"D.C. Batterbee(The University of Sheffield); N.D. Sims(The University of Sheffield, Sheffield)"
] |
The non-linear behaviour of electrorheological (ER) and magnetorheological (MR) dampers makes it difficult to design effective control strategies, and as a consequence a wide range of control systems have been proposed in the literature. These previous studies have not always compared the performance to equivalent passive systems, alternative control designs, or idealised active systems. As a result it is often impossible to compare the performance of different smart damper control strategies. This article provides some insight into the relative performance of two MR damper control strategies: on/off control and feedback linearisation. The performance of both strategies is benchmarked against ideal passive, semi-active and fully active damping. The study relies upon a previously developed model of an MR damper, which in this work is validated experimentally under closed-loop conditions with a broadband mechanical excitation. Two vibration isolation case studies are investigated: a single-degree-of-freedom mass-isolator, and a two-degree-of-freedom system that represents a vehicle suspension system. In both cases, a variety of broadband mechanical excitations are used and the results analysed in the frequency domain. It is shown that although on/off control is more straightforward to implement, its performance is worse than the feedback linearisation strategy, and can be extremely sensitive to the excitation conditions.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001471106
|
oai_dc
|
Modeling and fast output sampling feedback control of a smart Timoshenko cantilever beam
|
Modeling and fast output sampling feedback control of a smart Timoshenko cantilever beam
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"T.C. Manjunath(Indian Institute of Technology Bombay); B. Bandyopadhyay(Indian Institute of Technology Bombay)"
] |
This paper features about the modeling and design of a fast output sampling feedback controller for a smart Timoshenko beam system for a SISO case by considering the first 3 vibratory modes. The beam structure is modeled in state space form using FEM technique and the Timoshenko beam theory by dividing the beam into 4 finite elements and placing the piezoelectric sensor/actuator at one location as a collocated pair, i.e., as surface mounted sensor/actuator, say, at FE position 2. State space models are developed for various aspect ratios by considering the shear effects and the axial displacements. The effects of changing the aspect ratio on the master structure is observed and the performance of the designed FOS controller on the beam system is evaluated for vibration control.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001471102
|
oai_dc
|
Ultrasonics and electromagnetics for a wireless corrosion sensing system embedded in structural concrete
|
Ultrasonics and electromagnetics for a wireless corrosion sensing system embedded in structural concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"K. Hietpas(University of Illinois at Urbana-Champaign); B. Ervin(University of Illinois at Urbana-Champaign); J. Banasiak(University of Illinois at Urbana-Champaign); D. Pointer(University of Illinois at Urbana-Champaign); D.A. Kuchma(University of Illinois at Urbana-Champaign); H. Reis(University of Illinois at Urbana-Champaign); J.T. Bernhard(University of Illinois at Urbana-Champaign)"
] |
This work describes ongoing development of an embedded sensor system for the early detection and prevention of deterioration of reinforcing steel tendons within reinforced concrete. These devices will evaluate the condition of the steel tendon using ultrasonic techniques and then wirelessly transmit this data to the outside world without human intervention. The ultrasonic transducers and the interpretation of the sensed signals that allow detection and prognosis of tendon condition are detailed. Electrical characterization of concrete mixtures used in bridge construction is conducted and a wideband microstrip antenna is designed and fabricated to operate between 2.4 and 2.5 GHz when embedded in such a medium. Simulations and measurements of the embedded antenna element are presented. Transceiver selection and implementation are discussed as well as future work in operational protocols, sensor networking, and power sources. By implementing commercially available off-the-shelf components whenever possible, these devices have the potential to save millions of dollars a year in evaluation, repair and replacement of reinforced concrete.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001471109
|
oai_dc
|
Analytical solutions to piezoelectric bimorphs based on improved FSDT beam model
|
Analytical solutions to piezoelectric bimorphs based on improved FSDT beam model
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Yan-guo Zhou(Zhejiang University); Yun-min Chen(Zhejiang University); Hao-jiang Ding(Zhejiang University)"
] |
This paper presents an efficient and accurate coupled beam model for piezoelectric bimorphs based on improved first-order shear deformation theory (FSDT). The model combines the equivalent single layer approach for the mechanical displacements and a layerwise modeling for the electric potential. General electric field function is proposed to reasonably approximate the through-the-thickness distribution of the applied and induced electric potentials. Layerwise defined shear correction factor (k) accounting for nonlinear shear strain distribution is introduced into both the shear stress resultant and the electric displacement integration. Analytical solutions for free vibrations and forced response under electromechanical loads are obtained for the simply supported piezoelectric bimorphs with series or parallel arrangement, and the numerical results for various length-to-thickness ratios are compared with the exact two-dimensional piezoelasticity solution. Excellent predictions with low error estimates of local and global responses as well as the modal frequencies are observed.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001471099
|
oai_dc
|
Wideband Lamb wave analysis based on continuous wavelet transform
|
Wideband Lamb wave analysis based on continuous wavelet transform
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Lihua Shi(Nanjing Engineering Institute); Xinwei Wang(Nanjing University of Aeronautics and Astronautics); Gang Li(Nanjing University of Aeronautics and Astronautics); Lingyan Zhang(Nanjing Engineering Institute)"
] |
In Lamb wave detection of damages in smart structures, the excitation pulse is usually designed as a narrow band burst wave for the convenience of analysis and recognition. However, the wideband excitation can excite more modes in plate/shell structure and thus provides extra information for changes of the structure. This paper presents a method that can extract information in wideband Lamb wave signals. By transforming the detected signals into various sub-frequency band, the measured signal can be converted to its equivalences of narrow band excitations, therefore, the information in different frequency bands can be acquired from a single test and in the same time the complicity of wideband signal can be simplified. Some test results are provided to verify this method.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001471083
|
oai_dc
|
Advanced signal processing for enhanced damage detection with piezoelectric wafer active sensors
|
Advanced signal processing for enhanced damage detection with piezoelectric wafer active sensors
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Lingyu Yu(University of South Carolina Columbia); Victor Giurgiutiu(University of South Carolina Columbia)"
] |
Advanced signal processing techniques have been long introduced and widely used in structural health monitoring (SHM) and nondestructive evaluation (NDE). In our research, we applied several signal processing approaches for our embedded ultrasonic structural radar (EUSR) system to obtain improved damage detection results. The EUSR algorithm was developed to detect defects within a large area of a thin-plate specimen using a piezoelectric wafer active sensor (PWAS) array. In the EUSR, the discrete wavelet transform (DWT) was first applied for signal de-noising. Secondly, after constructing the EUSR data, the short-time Fourier transform (STFT) and continuous wavelet transform (CWT) were used for the time-frequency analysis. Then the results were compared thereafter. We eventually chose continuous wavelet transform to filter out from the original signal the component with the excitation signal? frequency. Third, cross correlation method and Hilbert transform were applied to A-scan signals to extract the time of flight (TOF) of the wave packets from the crack. Finally, the Hilbert transform was again applied to the EUSR data to extract the envelopes for final inspection result visualization. The EUSR system was implemented in LabVIEW. Several laboratory experiments have been conducted and have verified that, with the advanced signal processing approaches, the EUSR has enhanced damage detection ability.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001471086
|
oai_dc
|
Smart geophysical characterization of particulate materials in a laboratory
|
Smart geophysical characterization of particulate materials in a laboratory
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"권태혁(KAIST); 조계춘(KAIST)"
] |
Elastic and electromagnetic waves can be used to gather important information about particulate materials. To facilitate smart geophysical characterization of particulate materials, their fundamental properties are discussed and experimental procedures are presented for both elastic and electromagnetic waves. The first application is related to the characterization of particulate materials using shear waves, concentrating on changes in effective stress during consolidation, multi-phase phenomena with relation to capillarity, and microscale characteristics of particles. The second application involves electromagnetic waves, focusing on stratigraphy detection in layered soils, estimation of void ratio and its spatial distribution, and conduction in unsaturated soils. Experimental results suggest that shear waves allow studying particle contact phenomena and the evolution of interparticle forces, while electromagnetic waves give insight into the characteristics of the fluid phase and its spatial distribution.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001471059
|
oai_dc
|
Sensor placement strategy for high quality sensing in machine health monitoring
|
Sensor placement strategy for high quality sensing in machine health monitoring
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Robert X. Gao(University of Massachusetts); Changting Wang(General Electric Corporation); Shuangwen Sheng(University of Massachusetts)"
] |
This paper presents a systematic investigation of the effect of sensor location on the data quality and subsequently, on the effectiveness of machine health monitoring. Based on an analysis of the signal propagation process from the defect location to the sensor, numerical simulations using finite element modeling were conducted on a bearing test bed to determine the signal strength at several representative sensor locations. The results showed that placing sensors closely to the machine component being monitored is critical to achieving high signal-to-noise ratio, thus improving the data quality. Using millimeter-sized piezoceramic plates, the obtained results were evaluated experimentally. A comparison with a set of commercial vibration sensors verified the developed structural dynamics-based sensor placement strategy. It further demonstrated that the proposed shock wave-based sensing technique provided an effective alternative to vibration measurement, while requiring less space for sensor installation.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001471077
|
oai_dc
|
The future role of smart structure systems in modern aircraft
|
The future role of smart structure systems in modern aircraft
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"J. Becker(Technical University of Munich); W. Luber(Military Aircraft); J. Simpson(Military Aircraft); K. Dittrich(Military Aircraft)"
] |
The paper intends to summarize some guidelines for future smart structure system application in military aircraft. This preview of system integration is based upon a review on approximately one and a half decades of application oriented aerospace related smart structures research. Achievements in the area of structural health monitoring, adaptive shape, adaptive load bearing devices and active vibration control have been reached, potentials have been identified, several feasibility studies have been performed and some smart technologies have been already implemented. However the realization of anticipated visions and previously initial timescales announced have been rather too optimistic. The current development shall be based on a more realistic basis including more emphasis on fundamental aircraft strength, stiffness, static and dynamic load and stability requirements of aircraft and interdisciplinary integration requirements and improvements of integrated actors, actuator systems and control systems including micro controllers.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001471067
|
oai_dc
|
Distributed crack sensors featuring unique memory capability for post-earthquake condition assessment of RC structures
|
Distributed crack sensors featuring unique memory capability for post-earthquake condition assessment of RC structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Genda Chen(University of Missouri-Rolla); Ryan McDaniel(University of Missouri-Rolla); Shishuang Sun(University of Missouri-Rolla); David Pommerenke(University of Missouri-Rolla); James Drewniak(University of Missouri-Rolla)"
] |
A new design of distributed crack sensors based on the topological change of transmission line cables is presented for the condition assessment of reinforced concrete (RC) structures during and immediately after an earthquake event. This study is primarily focused on the performance of cable sensors under dynamic loading, particularly a feature that allows for some memory of the crack history of an RC member. This feature enables the post-earthquake condition assessment of structural members such as RC columns, in which the earthquake-induced cracks are closed immediately after an earthquake event due to gravity loads, and are visually undetectable. Factors affecting the onset of the feature were investigated experimentally with small-scale RC beams under cyclic loading. Test results indicated that both crack width and the number of loading cycles were instrumental in the onset of the memory feature of cable sensors. Practical issues related to dynamic acquisition with the sensors are discussed. The sensors were proven to be fatigue resistant from shake table tests of RC columns. The sensors continued to show useful performance after the columns can no longer support additional loads.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464150
|
oai_dc
|
The use of SMA wire dampers to enhance the seismic performance of two historical Islamic minarets
|
The use of SMA wire dampers to enhance the seismic performance of two historical Islamic minarets
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Adel El-Attar(Cairo University); Ahmed Saleh(Cairo University); Islam El-Habbal(Cairo University); Abdel Hamid Zaghw(Cairo University); Ashraf Osman(Cairo University)"
] |
This paper represents the final results of a research program sponsored by the European Commission through project WIND-CHIME (Wide Range Non-INtrusive Devices toward Conservation of HIstorical Monuments in the MEditerranean Area), in which the possibility of using advanced seismic
protection technologies to preserve historical monuments in the Mediterranean area is investigated. In the current research, the dynamic characteristics of two outstanding Mamluk-Style minarets, which similar minarets were reported to experience extensive damage during Dahshur 1992 earthquake, are investigated. The first minaret is the Qusun minaret (1337 A.D, 736 Hijri Date (H.D)) located in El-Suyuti cemetery on the southern side of the
Salah El-Din citadel. The minaret is currently separated from the surrounding building and is directly resting on the ground (no vaults underneath). The total height of the minaret is 40.28 meters with a base rectangular shaft of about 5.42 × 5.20 m. The second minaret is the southern minaret of Al-Sultaniya (1340 A.D, 739 H.D). It is located about 30.0 meters from Qusun minaret, and it is now standing alone but it seems that it used to be attached to a huge unidentified structure. The style of the minaret and its size attribute it to the first half of the fourteenth century. The minaret total height is 36.69 meters and has a 4.48 × 4.48 m rectangular base. Field investigations were conducted to obtain: (a) geometrical description of the minarets, (b) material properties of the minarets’ stones, and (c) soil conditions at the minarets’ location. Ambient vibration tests were performed to determine the modal parameters of the minarets such as natural frequencies and mode shapes. A 1/16th scale model of Qusun minaret was constructed at Cairo University Concrete Research Laboratory and tested under free vibration with and without SMA wire dampers. The contribution of SMA wire dampers to the structural damping coefficient was evaluated under different vertical loads and vibration amplitudes. Experimental results were used along with the field investigation data to develop a realistic 3-D finite element model that can be used for seismic risk evaluation of the minarets. Examining the updated finite element models under different seismic excitations indicated the vulnerability of such structures to earthquakes with medium to high a/v ratio. The use of SMA wire dampers was found feasible for reducing the seismic risk for this type of structures.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464143
|
oai_dc
|
Influence of geometry and loading conditions on the dynamics of martensitic fronts
|
Influence of geometry and loading conditions on the dynamics of martensitic fronts
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Arkadi Berezovski(Tallinn University of Technology)"
] |
Damping capacity of SMA damping devices is simulated numerically under distinct geometry and loading conditions. Two-dimensional numerical simulations are performed on the basis of a phenomenological model of dynamics of martensite-austenite phase boundaries. Results of the simulations predict the time delay and the value of the stress transferred to other parts of a construction by a damper device.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464151
|
oai_dc
|
Aseismic protection of historical structures using modern retrofitting techniques
|
Aseismic protection of historical structures using modern retrofitting techniques
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"C. A. Syrmakezis(National Technical University of Athens); A. K. Antonopoulos(National Technical University of Athens); O. A. Mavrouli(National Technical University of Athens)"
] |
For historical masonry structures existing in the Mediterranean area, structural strengthening is of primary importance due to the continuous earthquake threat that is posed on them. Proper retrofitting of historical structures involves a thorough understanding of their structural pathology, before proceeding with any intervention measures. In this paper, a methodology is presented for the evaluation of the actual state of historical masonry structures, which can provide a useful tool for the seismic response assessment before and after the retrofitting. The methodology is mainly focused on the failure and vulnerability analysis of masonry structures using the finite element method. Using this methodology the retrofitting of historical structures with innovative techniques is investigated. The innovative technique presented here involves the exploitation of Shape Memory Alloy prestressed bars. This type of intervention is proposed because it ensures increased reversibility and minimization of interventions, in comparison with conventional retrofitting methods. In this paper, a case study is investigated for the demonstration of the proposed methodologies and techniques, which comprises a masonry Byzantine church and a masonry Cistern. Prestressed SMA alloy bars are placed into the load-bearing system of the structure. The seismic response of the non-retrofitted and the retrofitted finite element models are compared in terms of seismic energy dissipation and displacements diminution.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464142
|
oai_dc
|
Variability in mechanical properties and microstructure characterization of CuAlBe shape memory alloys for vibration mitigation
|
Variability in mechanical properties and microstructure characterization of CuAlBe shape memory alloys for vibration mitigation
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Fabio Casciati(University of Pavia); Casper van der Eijk(SINTEF Material and Chemistry)"
] |
Shape memory alloys (SMA) have been emphasized, studied and understood in the controlled world of the laboratory. Any attempt to implement one of these alloys in engineered products requires a jump from the controlled world of the laboratory to the actual environment of the application. The first step is to move from single grain specimens to multigrain samples. One works with a material for which any stock is different from that previously available. This paper reviews the milestones in the familiarization process the authors had to overcome during their cooperation within a project funded by the European Union. The main items cover transformation temperatures, thermal treatment and properties understanding.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464152
|
oai_dc
|
Use of copper shape memory alloys in retrofitting historical monuments
|
Use of copper shape memory alloys in retrofitting historical monuments
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"S. El-Borgi(Tunisia Polytechnic School); M. Neifar(Tunisia Polytechnic School); M. Ben Jabeur(Tunisia Polytechnic School); D. Cherif(Tunisia Polytechnic School); H. Smaoui(Tunisia Polytechnic School)"
] |
The potential use of Cu-based shape memory alloys (SMA) in retrofitting historical monuments is investigated in this paper. This study is part of the ongoing work conducted in Tunisia within the framework of the FP6 European Union project (WIND-CHIME) on the use of appropriate modern seismic protective systems in the conservation of Mediterranean historical buildings in earthquake-prone areas. The present investigation consists of a finite element simulation, as a preliminary to an experimental study where a cantilever masonry wall, representing a part of a historical monument, is subjected to monotonic and quasi-static cyclic loadings around a horizontal axis at the base level. The wall was retrofitted with an array of copper SMA wires with different crosssectional areas. A new model is proposed for heat-treated copper SMAs and is validated based on published experimental results. A series of nonlinear finite element analyses are then performed on the wall for the purpose of assessing the SMA device retrofitting capabilities. Simulation results show an improvement of the wall response for the case of monotonic and quasi-static cyclic loadings.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464148
|
oai_dc
|
Health monitoring of a historical monument in Jordan based on ambient vibration test
|
Health monitoring of a historical monument in Jordan based on ambient vibration test
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Khaldoon A. Bani-Hani(Qatar University Doha); Hazem S. Zibdeh(Jordan University of Science and Technology); Karim Hamdaoui(University of Pavia)"
] |
This paper summarizes the experimental vibration-based structural health monitoring study on a historical monument in Jordan. In this work, and within the framework of the European Commission funded project “Wide-Range Non-Intrusive Devices Toward Conservation of Historical Monuments in the Mediterranean Area”, a seven and a half century old minaret located in Ajloun (73 km north of the capital Amman) is studied. Because of their cultural value, touristic importance and the desire to preserve them for the future, only nondestructive tests were allowed for the experimental investigation of such heritage structures. Therefore, after dimensional measurements and determination of the current state of damage in the selected monument, ambient vibration tests are conducted to measure the accelerations at strategic locations of the system. Output-only modal identification technique is applied to extract the modal parameters such as natural frequencies and mode shapes. A Non-linear version of SAP 2000 computer program is used to develop a three-dimensional finite element model of the minaret. The developed numerical model is then updated according to the modal parameters obtained experimentally by the ambient-vibration test-results and the measured characteristics of old stone and deteriorated mortar. Moreover, a parametric identification method using the N4Sid state space model is employed to model the dynamic behavior of the minaret and to build up a robust, immune and noise tolerant model.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464149
|
oai_dc
|
Seismic vulnerability assessment of a historical building in Tunisia
|
Seismic vulnerability assessment of a historical building in Tunisia
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"S. El-Borgi(Tunisia Polytechnic School); S. Choura(Tunisia Polytechnic School); M. Neifar(Tunisia Polytechnic School); H. Smaoui(Tunisia Polytechnic School); M.S. Majdoub(Tunisia Polytechnic School); D. Cherif(Tunisia Polytechnic School)"
] |
A methodology for the seismic vulnerability assessment of historical monuments is presented in this paper. The ongoing work has been conducted in Tunisia within the framework of the FP6 European Union project
(WIND-CHIME) on the use of appropriate modern seismic protective systems in the conservation of Mediterranean historical buildings in earthquake-prone areas. The case study is the five-century-old Zaouia of Sidi Kassem Djilizi, located downtown Tunis, the capital of Tunisia. Ambient vibration tests were conducted on the case study using a number of force-balance accelerometers placed at selected locations. The Enhanced Frequency
Domain Decomposition (EFDD) technique was applied to extract the dynamic characteristics of the monument. A 3-D finite element model was developed and updated to obtain reasonable correlation between experimental and
numerical modal properties. The set of parameters selected for the updating consists of the modulus of elasticity in each wall element of the finite element model. Seismic vulnerability assessment of the case study was carried out
via three-dimensional time-history dynamic analyses of the structure. Dynamic stresses were computed and damage was evaluated according to a masonry specific plane failure criterion. Statistics on the occurrence, location and type of failure provide a general view for the probable damage level and mode. Results indicate a high vulnerability that confirms the need for intervention and retrofit.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464147
|
oai_dc
|
Health-monitoring and system-identification of an ancient aqueduct
|
Health-monitoring and system-identification of an ancient aqueduct
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Christis Z. Chrysostomou(Cyprus University of Technology); Themos Demetriou(Heras 13); Andreas Stassis(Higher Technical Institute)"
] |
An important historical monument of Cyprus is an aqueduct that was built in 1747 to provide water to the city of Larnaca and to its port. Because of its importance to the cultural heritage of Cyprus, the aqueduct has been selected as one of the case-study monuments in the project Wide-Range Non-Intrusive devices toward Conservation of Historical Monuments in the Mediterranean Area (WIND-CHIME). Detailed drawings of the aqueduct obtained from the Department of Antiquities of Cyprus have been used for the development of a computational model. The model was fine-tuned through the measurement of the dynamic characteristics of the aqueduct using forced and ambient vibrations. It should be noted that measurement of the dynamic characteristics of the structure were performed twice in a period of three years (June of 2004 and May of 2007). Significant differences were noted and they are attributed to soil structure interaction effects due to seasonal variations of the water-level in a nearby salt-lake. The system identification results for both cases are presented here. This monument was used to test the effectiveness of shape memory alloy (SMA) pre-stressed devices, which were developed during the course of the project, in protecting it without spoiling its monumental value.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464146
|
oai_dc
|
Investigation of masonry elasticity and shear moduli using finite element micro-models
|
Investigation of masonry elasticity and shear moduli using finite element micro-models
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"O. A. Mavrouli(National Technical University of Athens); C. A. Syrmakezis(National Technical University of Athens)"
] |
In this paper, a methodology for the estimation of masonry elasticity and shear moduli is presented, for linear elasticity considerations. The methodology is based on the assumption that for a “periodic” masonry wall, which is formed by the repetition of a basic unit containing blocks and mortar, the mechanical characteristics of the unit are representative of the characteristics of the entire wall. For their calculation, the finite element analysis method is used. A micro-model with finite elements simulating separately the blocks and the mortar is
developed. An equivalent finite element model, using an homogenous material is also developed and assuming equivalence of strains for the two models, the homogenous material properties are estimated. The efficiency of the
method and its applicability limits are investigated.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464144
|
oai_dc
|
Numerical analysis of a new SMA-based seismic damper system and material characterization of two commercial NiTi-alloys
|
Numerical analysis of a new SMA-based seismic damper system and material characterization of two commercial NiTi-alloys
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"J. S. Olsen(Norwegian University of Science and Technology); C. Van der Eijk(SINTEF Materials and Chemistry); Z. L. Zhang(Norwegian University of Science and Technology)"
] |
The work presented in this paper includes material characterisation and an investigation of suitability in seismic dampers for two commercially available NiTi-alloys, along with a numerical analysis of a new damper system employing composite NiTi-wires. Numerical simulations of the new damper system are conducted, using Brinson’s one-dimensional constitutive model for shape memory alloys, with emphasis on the system’s energy dissipation capabilities. The two alloys tested showed some unwanted residual strain at temperatures higher than Af, possibly due to stress concentrations near inclusions in the material. These findings show that the alloys are not
ideal, but may be employed in a seismic damper if precautions are made. The numerical investigations indicate that using composite NiTi-wires in a seismic damper enhances the energy dissipation capabilities for a wider working temperature range.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464145
|
oai_dc
|
Experimental and numerical studies toward the implementation of shape memory alloy ties in masonry structures
|
Experimental and numerical studies toward the implementation of shape memory alloy ties in masonry structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Sara Casciati(University of Catania); Karim Hamdaoui(University of Pavia)"
] |
The use of pre-tensioned shape memory alloy (SMA) wires to retrofit historic masonry structures is investigated. A small wall, serving as a prototype masonry specimen, is constructed to undergo a series of shakingtable
tests. It is first studied in its original state, and its dynamic characteristics (in terms of modal frequencies) are extracted from the recorded signals. The results are then compared with those obtained when an increasing
number of couples of pre-stressed SMA wires are introduced in the specimen to link the bricks together. A threedimensional finite element model of the specimen is developed and calibrated according to the modal parameters
identified from each experimental test (with and without SMA wires). The calibration process is conducted by enhancing the masonry mechanical behaviour. The results and the effectiveness of the approach are presented.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001464155
|
oai_dc
|
Application of shape memory alloy prestressing devices on an ancient aqueduct
|
Application of shape memory alloy prestressing devices on an ancient aqueduct
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Christis Z. Chrysostomou(Cyprus University of Technology); Andreas Stassis(Higher Technical Institute); Themos Demetriou(Heras 13); Karim Hamdaoui(University of Pavia)"
] |
The results of the application of shape memory alloy (SMA) prestressing devices on an aqueduct are presented in this paper. The aqueduct was built in 1747 to provide water to the city of Larnaca and to its port. Because of its importance to the cultural heritage of Cyprus, the aqueduct has been selected as one of the casestudy monuments in the project Wide-Range Non-Intrusive devices toward Conservation of Historical Monuments in the Mediterranean Area (WIND-CHIME). The Department of Antiquities of Cyprus, acting in a pioneering way, have given their permission to apply the devices in order to investigate their effectiveness in providing protection to the monument against probable catastrophic effects of earthquake excitation. The dynamic characteristics of the structure were determined in two separate occasions and computational models were developed that matched very closely the dynamic characteristics of the structure. In this paper the experimental setup and the measured changes in the dynamic characteristics of the monument after the application of the SMA devices are described.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001450059
|
oai_dc
|
Rapid-to-deploy reconfigurable wireless structural monitoring systems using extended-range
|
Rapid-to-deploy reconfigurable wireless structural monitoring systems using extended-range
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Junhee Kim(University of Michigan); R. Andrew Swartz(Michigan Technological University); Jerome P. Lynch(University of Michigan); Jong-Jae Lee(Sejong University); Chang-Geun Lee(Expressway and Transportation Research Institute)"
] |
Wireless structural monitoring systems consist of networks of wireless sensors installed to record the loading environment and corresponding response of large-scale civil structures. Wireless monitoring systems are desirable because they eliminate the need for costly and labor intensive installation of coaxial wiring in a structure. However, another advantageous characteristic of wireless sensors is their installation modularity. For example, wireless sensors can be easily and rapidly removed and reinstalled in new locations on a structure if the need arises. In this study, the reconfiguration of a rapid-to-deploy wireless structural monitoring system is proposed for monitoring short- and medium-span highway bridges. Narada wireless sensor nodes using power amplified radios are adopted to achieve long communication ranges. A network of twenty Narada wireless sensors is installed on the Yeondae Bridge (Korea) to measure the global response of the bridge to controlled truck loadings. To attain acceleration measurements in a large number of locations on the bridge, the wireless monitoring system is installed three times, with each installation concentrating sensors in one localized area of the bridge. Analysis of measurement data after installation of the three monitoring system configurations leads to reliable estimation of the bridge modal properties, including mode shapes.
|
토목공학
| null |
kci_detailed_000091.xml
|
|||
ART001450079
|
oai_dc
|
Experimental validation of a multi-level damage localization technique with distributed computation
|
Experimental validation of a multi-level damage localization technique with distributed computation
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Guirong Yan(Purdue University); Weijun Guo(Washington University); Shirley J. Dyke(Purdue University); Gregory Hackmann(Washington University); Chenyang Lu(Washington University)"
] |
This study proposes a multi-level damage localization strategy to achieve an effective damage detection system for civil infrastructure systems based on wireless sensors. The proposed system is designed for use of distributed computation in a wireless sensor network (WSN). Modal identification is achieved using the frequency-domain decomposition (FDD) method and the peak-picking technique. The ASH (angle-between-string-and-horizon) and AS (axial strain) flexibility-based methods are employed for identifying and localizing damage. Fundamentally, the multi-level damage localization strategy does not activate all of the sensor nodes in the network at once. Instead, relatively few sensors are used to perform coarse-grained damage localization; if damage is detected, only those sensors in the potentially damaged regions are incrementally added to the network to perform finer-grained damage localization. In this way, many nodes are able to remain asleep for part or all of the multi-level interrogations, and thus the total energy cost is reduced considerably. In addition, a novel distributed computing strategy is also proposed to reduce the energy consumed in a sensor node, which distributes modal identification and damage detection tasks across a WSN and only allows small amount of useful intermediate results to be transmitted wirelessly. Computations are first performed on each leaf node independently, and the aggregated information is transmitted to one cluster head in each cluster. A second stage of computations are performed on each cluster head, and the identified operational deflection shapes and natural frequencies are transmitted to the base station of the WSN. The damage indicators are extracted at the base station. The proposed strategy yields a WSN-based SHM system which can effectively and automatically identify and localize damage, and is efficient in energy usage. The proposed strategy is validated using two illustrative numerical simulations and experimental validation is performed using a cantilevered beam.
|
토목공학
| null |
kci_detailed_000092.xml
|
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