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ART001555371
|
oai_dc
|
Modeling of temperature distribution in a reinforced concrete supertall structure based on structural health monitoring data
|
Modeling of temperature distribution in a reinforced concrete supertall structure based on structural health monitoring data
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Y.Q. Ni(The Hong Kong Polytechnic University); P. Zhang(The Hong Kong Polytechnic University); X.W. Ye(The Hong Kong Polytechnic University); K.C. Lin(The Hong Kong Polytechnic University); W.Y. Liao(The Hong Kong Polytechnic University)"
] |
A long-term structural health monitoring (SHM) system comprising over 700 sensors of sixteen types has been implemented on the Guangzhou Television and Sightseeing Tower (GTST) of 610 m high for real-time monitoring of the structure at both construction and service stages. As part of this sophisticated SHM system, 48 temperature sensors have been deployed at 12 cross-sections of the reinforced concrete inner structure of the GTST to provide on-line monitoring via a wireless data transmission system. In this paper, the differential temperature profiles in the reinforced concrete inner structure of the GTST, which are mainly caused by solar radiation, are recognized from the monitoring data with the purpose of understanding the temperature-induced structural internal forces and deformations. After a careful examination of the pre-classified temperature measurement data obtained under sunny days and non-sunny days, common characteristic of the daily temperature variation is observed from the data acquired in sunny days. Making use of 60-day temperature measurement data obtained in sunny days, statistical patterns of the daily rising temperature and daily descending temperature are synthesized, and temperature distribution models of the reinforced concrete inner structure of the GTST are formulated using linear regression analysis. The developed monitoring-based temperature distribution models will serve as a reliable input for numerical prediction of the temperature-induced deformations and provide a robust basis to facilitate the design and construction of similar structures in consideration of thermal effects.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001555358
|
oai_dc
|
Numerical analysis of Brazilian split test on concrete cylinder
|
Numerical analysis of Brazilian split test on concrete cylinder
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Adam Wosatko(Cracow University of Technology); Andrzej Winnicki(Cracow University of Technology); Jerzy Pamin(Cracow University of Technology)"
] |
The paper presents simulations of the Brazilian test using two numerical models. Both models are regularized in order to obtain results independent of discretization. The first one, called gradient damage, is refined by additional averaging equation which contains gradient terms and an internal length scale as localization limiter. In the second one, called viscoplastic consistency model, the yield function depends on the viscoplastic strain rate. In this model regularization properties are governed by the assumed strain rate. The two models are implemented in the FEAP finite element package and compared in this paper. Parameter studies of the split test are performed in order to point out the features of each model.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001555364
|
oai_dc
|
Modeling the effects of additives on rheological properties of fresh self-consolidating cement paste using artificial neural network
|
Modeling the effects of additives on rheological properties of fresh self-consolidating cement paste using artificial neural network
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Alireza Mohebbi(University of Tehran); Mohammad Shekarchi(University of Tehran); Shima Mohebbi(University of Tehran); Mehrdad Mahoutian(University of Tehran)"
] |
The main purpose of this study includes investigation of the rheological properties of fresh self consolidating cement paste containing chemical and mineral additives using Artificial Neural Network (ANN) model. In order to develop the model, 200 different mixes are cast in the laboratory as a part of an extensive experimental research program. The data used in the ANN model are arranged in a format of fourteen input parameters covering water-binder ratio, four different mineral additives (calcium carbonate,metakaolin, silica fume, and limestone), five different superplasticizers based on the poly carboxylate and naphthalene and four different Viscosity Modified Admixtures (VMAs). Two common output parameters including the mini slump value and flow cone time are chosen for measuring the rheological properties of fresh self consolidating cement paste. Having validated the model, the influence of effective parameters on the rheological properties of fresh self consolidating cement paste is investigated based on the ANN model outputs. The output results of the model are then compared with the results of previous studies performed by other researchers. Ultimately, the analysis of the model outputs determines the optimal percentage of additives which has a strong influence on the rheological properties of fresh self consolidating cement paste. The proposed ANN model shows that metakaolin and silica fume affect the rheological properties in the same manner. In addition, for providing the suitable rheological properties, the ANN model introduces the optimal percentage of metakaolin, silica fume, calcium carbonate and limestone as 15, 15, 20 and 20% by cement weight, respectively.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001555399
|
oai_dc
|
Three-dimensional numerical simulation and cracking analysis of fiber-reinforced cement-based composites
|
Three-dimensional numerical simulation and cracking analysis of fiber-reinforced cement-based composites
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jun Huang(South China University of Technology); Peiyan Huang(Hohai University)"
] |
Three-dimensional graphic objects created by MATLAB are exported to the AUTOCAD program through the MATLAB handle functions. The imported SAT format files are used to produce the finite element mesh for MSC.PATRAN. Based on the Monte-Carlo random sample principle, the material heterogeneity of cement composites with randomly distributed fibers is described by the WEIBULL distribution function. In this paper, a concept called “soft region” including micro-defects, micro-voids, etc. is put forward for the simulation of crack propagation in fiber-reinforced cement composites. The performance of the numerical model is demonstrated by several examples involving crack initiation and growth in the composites under three-dimensional stress conditions: tensile loading; compressive loading and crack growth along a bimaterial interface.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001555409
|
oai_dc
|
Prediction of chloride diffusion coefficient of concrete under flexural cyclic load
|
Prediction of chloride diffusion coefficient of concrete under flexural cyclic load
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Tran Van Mien(HoChiMinh City University of Technology); Toyoharu Nawa(Hokkaido University); Boonchai Stitmannaithum(Chulalongkorn University)"
] |
This paper presented the model to predict the chloride diffusion coefficient in tension zone of plain concrete under flexural cyclic load. The fictitious crack based analytical model was used together with the stress degradation law in cracked zone to predict crack growth of plain concrete beams under flexural cyclic load. Then, under cyclic load, the chloride diffusion, in the steady state and one dimensional regime, through the tension zone of the plain concrete beam, in which microcracks were formed by a large number of cycles, was simulated with assumptions of continuously straight crack and uniform-size crack. The numerical analysis in terms of the chloride diffusion coefficient, D_tot, normalized D_tot, crack width and crack length was issued as a function of the load cycle, N, and load level, SR. The nonlinear model as regarding with the chloride diffusion coefficient in tension zone and the load level was proposed. According to this model, the chloride diffusion increases with increasing load level. The predictions using model fit well with experimental data when we adopted suitable crack density and tortuosity parameter.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001555388
|
oai_dc
|
Global seismic damage assessment of high-rise hybrid structures
|
Global seismic damage assessment of high-rise hybrid structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Xilin Lu(Tongji University); Zhihua Huang(Tongji University); Ying Zhou(Tongji University)"
] |
Nowadays, many engineers believe that hybrid structures with reinforced concrete central core walls and perimeter steel frames offer an economical method to develop the strength and stiffness required for seismic design. As a result, a variety of such structures have recently been applied in actual construction. However, the performance-based seismic design of such structures has not been investigated systematically. In the performance-based seismic design, quantifying the seismic damage of complete structures by damage indices is one of the fundamental issues. Four damage states and the final softening index at each state for high-rise hybrid structures are suggested firstly in this paper. Based on nonlinear dynamic analysis, the relation of the maximum inter-story drift, the main structural characteristics, and the final softening index is obtained. At the same time, the relation between the maximum inter-story drift and the maximum roof displacement over the height is also acquired. A double-variable index accounting for maximum deformation and cumulative energy is put forward based on the pushover analysis. Finally, a case study is conducted on a high-rise hybrid structure model tested on shaking table before to verify the suggested quantities of damage indices.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001555416
|
oai_dc
|
Modeling of concrete containing steel fibers: toughness and mechanical properties
|
Modeling of concrete containing steel fibers: toughness and mechanical properties
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ismail H. Cagatay(University of Cukurova); Riza Dincer(University of Cukurova)"
] |
In this study, effect of steel fibers on toughness and some mechanical properties of concrete were investigated. Hooked-end steel fibers were used in concrete samples with three volume fractions (vf) of 0.5%, 0.75% and 1% and for two aspect ratios (l/d) of 45 and 65. Compressive and flexural tensile strength and modulus of elasticity of concrete were determined for cylindrical, cubic and prismatic samples at the age of 7 and 28 days. The stress-strain curves of standard cylindrical specimens were studied to determine the effect of steel fibers on toughness of steel-fiber-reinforced concrete (SFRC). In addition, the relationship between compressive strength and the flexural tensile strength of SFRC were reported. Finally, a simple model was proposed to generate the stress-strain curves for SFRC based on strains corresponding to the peak compressive strength and 60% of peak compressive stress. The proposed model was shown to provide results in good correlation with the experimental results.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001628064
|
oai_dc
|
Optimization of particle packing by analytical and computer simulation approaches
|
Optimization of particle packing by analytical and computer simulation approaches
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Huan He(Delft University of Technology); Piet Stroeven(Delft University of Technology); Martijn Stroeven(Delft University of Technology); Lambertus Johannes Sluys(Delft University of Technology)"
] |
Optimum packing of aggregate is an important aspect of mixture design, since porosity may be reduced and strength improved. It may also cause a reduction in paste content and is thus of economic relevance too. Several mathematic packing models have been developed in the literature for optimization of mixture design. However in this study, numerical simulation will be used as the main tool for this purpose. A basic, simple theoretical model is used for approximate assessment of mixture optimization. Calculation and simulation will start from a bimodal mixture that is based on the mono-sized packing experiences. Tri-modal and multi-sized particle packing will then be discussed to find the optimum mixture. This study will demonstrate that computer simulation is a good alternative for mixture design and optimization when appropriate particle shapes are selected. Although primarily focusing on aggregate, optimization of blends of Portland cement and mineral admixtures could basically be approached in a similar way.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001628067
|
oai_dc
|
Statistical methods of investigation on the compressive strength of high–performance steel fiber reinforced concrete
|
Statistical methods of investigation on the compressive strength of high–performance steel fiber reinforced concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"P. Ramadoss(Pondicherry Engineering College); K. Nagamani(Anna University)"
] |
The contribution of steel fibers on the 28-day compressive strength of high-performance steel fiber reinforced concrete was investigated, is presented. An extensive experimentation was carried out over water-cementitious materials (w/cm) ratios ranging from 0.25 to 0.40, with silica fume- cementitious materials ratios from 0.05 to 0.15, and fiber volume fractions (Vf = 0.0, 0.5, 1.0 and 1.5%) with the aspect ratios of 80 and 53. Based on the test results of 44 concrete mixes, mathematical model was developed using statistical methods to quantify the effect of fiber content on compressive strength of HPSFRC in terms of fiber reinforcing index. The expression, being developed with strength ratios and not with absolute values of strengths, is independent of specimen parameters and is applicable to wide range of w/cm ratios, and used in the mix design of steel fiber reinforced concrete. The estimated strengths are within ±3.2% of the actual values. The model was tested for the strength results of 14 mixes having fiber aspect ratio of 53. On examining the validity of the proposed model, there exists a good correlation between the predicted values and the experimental values of different researchers. Equation is also proposed for the size effect of the concrete specimens.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001628061
|
oai_dc
|
Determination of double-K fracture parameters of concrete using split-tension cube test
|
Determination of double-K fracture parameters of concrete using split-tension cube test
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Shailendra Kumar(Guru Ghasidas Vishwavidyalaya); S.R. Pandey(National Institute of Technology)"
] |
This paper presents development of double-K fracture model for the split-tension cube specimen for determining the unstable fracture toughness and initial cracking toughness of concrete. There are some advantages of using of split-tension cube test like compactness and lightness over the existing specimen geometries in practice such as three-point bend test, wedge splitting test and compact tension specimen. The cohesive toughness of the material is determined using weight function having four terms for the split-tension cube specimen. Some empirical relations are also suggested for determining geometrical factors in order to calculate stress intensity factor and crack mouth opening displacement for the same specimen. The results of double-K fracture parameters of split-tension cube specimen are compared with those obtained for compact tension specimen. Finally, the influence of the width of the load-distribution of split-tension cube specimen on the double-K fracture parameters for laboratory size specimens is investigated. The input data required for determining double-K fracture parameters for both the specimen geometries are obtained using well known version of the Fictitious Crack Model.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001628066
|
oai_dc
|
Prediction of deflection of high strength steel fiber reinforced concrete beams and columns
|
Prediction of deflection of high strength steel fiber reinforced concrete beams and columns
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ilker Fatih Kara(Nigde University); Cengiz Dundar(Cukurova University)"
] |
This paper presents an analytical procedure for the analysis of high strength steel fiber reinforced concrete members considering the cracking effect in the serviceability loading range. Modifications to a previously proposed formula for the effective moment of inertia are presented. Shear deformation effect is also taken into account in the analysis, and the variation of shear stiffness in the cracked regions of members has been considered by reduced shear stiffness model. The effect of steel fibers on the behavior of reinforced concrete members have been investigated by the developed computer program based on the aforementioned procedure. The inclusion of steel fibers into high strength concrete beams and columns enhances the effective moment of inertia and consequently reduces the deflection reinforced concrete members. The contribution of the shear deformation to the total vertical deflection of the beams is found to be lower for beams with fibers than that of beams with no fibers. Verification of the proposed procedure has been confirmed from series of reinforced concrete beam and column tests available in the literature. The analytical procedure can provide an accurate and efficient prediction of deflections of high strength steel fiber reinforced concrete members due to cracking under service loads. This procedure also forms the basis for the three dimensional analysis of frames with steel fiber reinforced concrete members.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001628063
|
oai_dc
|
A decision support system for diagnosis of distress cause and repair in marine concrete structures
|
A decision support system for diagnosis of distress cause and repair in marine concrete structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Masoud Dehghani Champiri(Amirkabir University); Faramarz Moodi(Amirkabir University); S. Hossein Mousavizadegan(Amirkabir University)"
] |
Marine Structures are very costly and need a continuous inspection and maintenance routine. The most effective way to control the structural health is the application of an expert system that can evaluate the importance of any distress on the structure and provide a maintenance program. An extensive literature review, interviews with expert supervisors and a national survey are used to build a decision support system for concrete structures in sea environment. Decision trees are the main rules in this system. The system input is inspection information and the system output is the main cause(s) of distress(es) and the best repair method(s). Economic condition, severity of distress, distress situation, and new technologies and the most repeated classical methods are considered to choose the best repair method. A case study demonstrates the application of the developed decision support system for a type of marine structure.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001592932
|
oai_dc
|
Modelling seismically repaired and retrofitted reinforced concrete shear walls
|
Modelling seismically repaired and retrofitted reinforced concrete shear walls
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"W. Leonardo Cortés-Puentes(University of Ottawa); Dan Palermo(University of Ottawa)"
] |
The Finite Element Method (FEM) was employed to demonstrate that accurate simulations of seismically repaired and retrofitted reinforced concrete shear walls can be achieved provided a good analysis program with comprehensive models for material and structural behaviour is used. Furthermore, the analysis tool should have the capability to retain residual damage experienced by the original structure and carry it forward in the repaired and retrofitted structure. The focus herein is to provide quick, simple,but reliable modelling procedures for repair and retrofitting strategies such as concrete replacement, addition of diagonal reinforcing bars, bolting of external steel plates, and bonding of external steel plates and fibre reinforced polymer sheets, thus illustrating versatility in the modelling. Slender, squat, and slender-squat shear walls were investigated. The modelling utilized simple rectangular membrane elements for the concrete, truss bar elements for the steel and FRP retrofitting materials, and bond-link elements for the bonding interface between steel or FRP to concrete. The analyses satisfactorily simulated seismic behaviour, including lateral load capacity, displacement capacity, energy dissipation, hysteretic response, and failure mode.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001592921
|
oai_dc
|
Predicting the high temperature effect on mortar compressive strength by neural network
|
Predicting the high temperature effect on mortar compressive strength by neural network
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"N. Yuzer(Yildiz Technical University); B. Akbas(Gebze Institute of Technology); A.B. Kizilkanat(Yildiz Technical University)"
] |
Before deciding if structures exposed to high temperature are to be repaired or demolished, their final state should be carefully examined. Destructive and non-destructive testing methods are generally applied for this purpose. Compressive strength and color change in mortars are observed as a result of the effects of high temperature. In this study, ordinary and pozzolan-added mortar samples were produced using different aggregates, and exposed to 100, 200, 300, 600, 900 and 1200ºC. The samples were divided into two groups and cooled to room temperature in water and air separately. Compression tests were carried out on these samples, and the color change was evaluated by the Munsell Color System. The relationships between the change in compressive strength and color of mortars were determined by using a multilayered feed-forward Neural Network model trained with the back-propagation algorithm. The results showed that providing accurate estimates of compressive strength by using the color components and ultrasonic pulse velocity design parameters were possible using the approach adopted in this study.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001592978
|
oai_dc
|
Signal-based AE characterization of concrete with cement-based piezoelectric composite sensors
|
Signal-based AE characterization of concrete with cement-based piezoelectric composite 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); Lei Qin(University of Jinan)"
] |
The signal-based acoustic emission (AE) characterization of concrete fracture process utilizing home-programmed AE monitoring system was performed for three kinds of static loading tests (Cubic-splitting, Direct-shear and Pull-out). Each test was carried out to induce a distinct fracture mode of concrete. Apart from monitoring and recording the corresponding fracture process of concrete, various methods were utilized to distinguish the characteristics of detected AE waveform to interpret the information of fracture behavior of AE sources (i.e. micro-cracks of concrete). Further, more signal-based characters of AE in different stages were analyzed and compared in this study. This research focused on the relationship between AE signal characteristics and fracture processes of concrete. Thereafter, the mode of concrete fracture could be represented in terms of AE signal characteristics. By using cement-based piezoelectric composite sensors, the AE signals could be detected and collected with better sensitivity and minimized waveform distortion, which made the characterization of AE during concrete fracture process feasible. The continuous wavelet analysis technique was employed to analyze the wave-front of AE and figure out the frequency region of the P-wave & S-wave. Defined RA (rising amplitude), AF (average frequency) and P-wave & S-wave importance index were also introduced to study the characters of AE from concrete fracture. It was found that the characters of AE signals detected during monitoring could be used as an indication of the cracking behavior of concrete.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001592924
|
oai_dc
|
Probability-based durability design software for concrete structures subjected to chloride exposed environments
|
Probability-based durability design software for concrete structures subjected to chloride exposed environments
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"신경준(충남대학교); 김지상(서경대학교); 이광명(성균관대학교)"
] |
Although concrete is believed to be a durable material, concrete structures have been degraded by severe environmental conditions such as the effects of chloride and chemical, abrasion, and other deterioration processes. Therefore, durability evaluation has been required to ensure the long term serviceability of structures located in chloride exposed environments. Recently, probability-based durability analysis and design have proven to be reliable for the service-life predictions of concrete structures. This approach has been successfully applied to durability estimation and design of concrete structures. However, currently it is difficult to find an appropriate method engineers can use to solve these probability-based diffusion problems. In this paper, computer software has been developed to facilitate probability-based durability analysis and design. This software predict the chloride diffusion using the Monte Carlo simulation method based on Fick’s second law, and provides durability analysis and design solutions. A graphic user interface (GUI) is adapted for intuitive and easy use. The developed software is very useful not only for prediction of the service life but for the durability design of the concrete structures exposed to chloride environments.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001592983
|
oai_dc
|
Efficiency factor of high calcium Class F fly ash in concrete
|
Efficiency factor of high calcium Class F fly ash in concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"V. Sata(Khon Kaen University); P. Khammathit(Khon Kaen University); P. Chindaprasirt(Khon Kaen University)"
] |
This paper studied the cement efficiency factor (k factor) of high calcium Class F fly ash. This k factor represents a unit of fly ash with efficiency equivalent to k unit of cement. The high calcium Class F fly ash was used to replace cement in concrete. The modified Bolomey’s law with linear relationship was used for the analysis of the result of compressive strength, cement to water ratio (c/w) and fly ash to water ratio (f/w) by using the multi-linear regression to determine the k factor and other constants in the equations. The results of analysis were compared with the results from other researcher and showed that the k factor of high calcium Class F fly ash depends on the fineness of fly ash, replacement level and curing age. While the amount of CaO content in Class F fly ash not evident. Furthermore, necessary criteria and variables for the determination of the k factor including the use of the k factor in concrete mix design containing fly ash were proposed.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001592930
|
oai_dc
|
Fiber reinforced concrete properties- a multiscale approach
|
Fiber reinforced concrete properties- a multiscale approach
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Erez Gal(Ben-Gurion University); Roman Kryvoruk(Ben-Gurion University)"
] |
This paper describes the development of a fiber reinforced concrete (FRC) unit cell for analyzing concrete structures by executing a multiscale analysis procedure using the theory of homogenization. This was achieved through solving a periodic unit cell problem of the material in order to evaluate its macroscopic properties. Our research describes the creation of an FRC unit cell through the use of concrete paste generic information e.g. the percentage of aggregates, their distribution, and the percentage of fibers in the concrete. The algorithm presented manipulates the percentage and distribution of these aggregates along with fiber weight to create a finite element unit cell model of the FRC which can be used in a multiscale analysis of concrete structures.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001592994
|
oai_dc
|
Modeling the confined compressive strength of hybrid circular concrete columns using neural networks
|
Modeling the confined compressive strength of hybrid circular concrete columns using neural networks
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Andres W.C. Oreta(De La Salle University); Jason M.C. Ongpeng(De La Salle University)"
] |
With respect to rehabilitation, strengthening and retrofitting of existing and deteriorated columns in buildings and bridges, CFRP sheets have been found effective in enhancing the performance of existing RC columns by wrapping and bonding CFRP sheets externally around the concrete. Concrete columns and piers that are confined by both lateral steel reinforcement and CFRP are sometimes referred to as “hybrid” concrete columns. With the availability of experimental data on concrete columns confined by steel reinforcement and/or CFRP, the study presents modeling using artificial neural networks (ANNs) to predict the compressive strength of hybrid circular RC columns. The prediction of the ultimate confined compressive strength of RC columns is very important especially when this value is used in estimating the capacity of structures. The present ANN model used as parameters for the confining materials the lateral steel ratio (ρs) and the FRP volumetric ratio (ρFRP). The model gave good predictions for three types of confined columns: (a) columns confined with steel reinforcement only, (b) CFRP confined columns, and (c) hybrid columns confined by both steel and CFRP. The model may be used for predicting the compressive strength of existing circular RC columns confined with steel only that will be strengthened or retrofitted using CFRP.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001602961
|
oai_dc
|
Reliability based calibration of the capacity design rule of reinforced concrete beam-column joints
|
Reliability based calibration of the capacity design rule of reinforced concrete beam-column joints
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"George C. Thomos(National Technical University of Athens); Constantin G. Trezos(National Technical University of Athens)"
] |
The capacity design rule for beam-column joints, as adopted by the EC8, forces the formation of the plastic hinges to be developed in beams rather than in columns. This is achieved by deriving the design moments of the columns of a joint from equilibrium conditions, assuming that plastic hinges with their possible overstrengths have been developed in the adjacent beams of the joint. In this equilibrium the parameters (dimensions, material properties, axial forces etc) are, in general, random variables. Hence,the capacity design is associated with a probability of non-compliance (probability of failure). In the present study the probability of non-compliance of the capacity design rule of joints is being calculated by assuming the basic variables as random variables. Parameters affecting this probability are examined and a modification of the capacity design rule for beam-column joints is proposed, in order to achieve uniformity of the safety level.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001602964
|
oai_dc
|
Site-response effects on RC buildings isolated by triple concave friction pendulum bearings
|
Site-response effects on RC buildings isolated by triple concave friction pendulum bearings
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Sevket Ates(Karadeniz Technical University); Muhammet Yurdakul(Bayburt University)"
] |
The main object of this study is to evaluate the seismic response effects on a reinforced concrete building isolated by triple concave friction pendulum (TCFP) bearings. The site-response effects arise from the difference in the local soil conditions at the support points of the buildings. The local soil conditions are, therefore, considered as soft, medium and firm; separately. The results on the responses of the isolated building are compared with those of the non-isolated. The building model used in the time history analysis, which is a two-dimensional and eight-storey reinforced concrete building with and without the seismic isolation bearings and/or the local soil conditions, is composed of two-dimensional moment resisting frames for superstructure and of plane elements featuring plane-stress for substructure. The TCFP bearings for isolating the building are modelled as of a series arrangement of the three single concave friction pendulum (SCFP) bearings. In order to investigate the efficiency of both the seismic isolation bearings and the site-response effects on the buildings, the time history analyses are elaborately conducted. It is noted that the site-response effects are important for the isolated building constructed on soft, medium or firm type local foundation soil. The results of the analysis demonstrate that the siteresponse has significant effects on the response values of the structure-seismic isolation-foundation soil system.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001602959
|
oai_dc
|
Properties of artificial lightweight aggregates made from waste sludge
|
Properties of artificial lightweight aggregates made from waste sludge
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"I.J. Chiou(Nanya Institute of Technology); C.H. Chen(National Taipei University)"
] |
In this investigation, reservoir sediment and municipal sewage sludge were sintered to form the artificial lightweight aggregates. The sintered aggregates were compared with the commercialized lightweight aggregates to in terms of potential alkali-silica reactivity and chemical stability based on analyses of their physical and chemical properties, leaching of heavy metal, alkali-silica reactivity, crystal phase species and microstructure. Experimental results demonstrated that the degree of sintering of an aggregate affected the chemical resistance more strongly than did its chemical composition. According to ASTM C289-94, all potential alkali-silica reactivity of artificial lightweight aggregates were in the harmless zone, while the potential reactivity of artificial lightweight aggregates made from reservoir sediment and municipal sewage sludge were much lower than those of traditional lightweight aggregates.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001602962
|
oai_dc
|
The origins and evolution of cement hydration models
|
The origins and evolution of cement hydration models
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Tiantian Xie(Tennessee Technological University Cookeville); Joseph J. Biernacki(Tennessee Technological University Cookeville)"
] |
Our ability to predict hydration behavior is becoming increasingly relevant to the concrete community as modelers begin to link material performance to the dynamics of material properties and chemistry. At early ages, the properties of concrete are changing rapidly due to chemical transformations that affect mechanical, thermal and transport responses of the composite. At later ages, the resulting, nano-, micro-, meso- and macroscopic structure generated by hydration will control the life-cycle performance of the material in the field. Ultimately, creep, shrinkage, chemical and physical durability, and all manner of mechanical response are linked to hydration. As a way to enable the modeling community to better understand hydration, a review of hydration models is presented offering insights into their mathematical origins and relationships one-to-the-other. The quest for a universal model begins in the 1920’s and continues to the present, and is marked by a number of critical milestones. Unfortunately, the origins and physical interpretation of many of the most commonly used models have been lost in their overuse and the trail of citations that vaguely lead to the original manuscripts. To help restore some organization, models were sorted into four categories based primarily on their mathematical and theoretical basis: (1) mass continuity-based, (2) nucleation-based, (3) particle ensembles, and (4) complex multiphysical and simulation environments. This review provides a concise catalogue of models and in most cases enough detail to derive their mathematical form. Furthermore, classes of models are unified by linking them to their theoretical origins, thereby making their derivations and physical interpretations more transparent. Models are also used to fit experimental data so that their characteristics and ability to predict hydration calorimetry curves can be compared. A sort of evolutionary tree showing the progression of models is given along with some insights into the nature of future work yet needed to develop the next generation of cement hydration models.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001602963
|
oai_dc
|
Influence of particle packing on fracture properties of concrete
|
Influence of particle packing on fracture properties of concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Huan He(Delft University of Technology); Piet Stroeven(Delft University of Technology); Martijn Stroeven(Delft University of Technology); Lambertus Johannes Sluys(Delft University of Technology)"
] |
Particle packing on meso-level has a significant influence on workability of fresh concrete and also on the mechanical and durability properties of the matured material. It was demonstrated earlier that shape exerts but a marginal influence on the elastic properties of concrete provided being packed to the same density, which is not necessarily the case with different types of aggregate. Hence, elastic properties of concrete can be treated as approximately structure-insensitive parameters. However, fracture behaviour can be expected structure-sensitive. This is supported by the present study based on discrete element method (DEM) simulated three-phase concrete, namely aggregate, matrix and interfacial transition zones (ITZs). Fracture properties are assessed with the aid of a finite element method (FEM) based on the damage materials model. Effects on tensile strength due to grain shape and packing density are investigated. Shape differences are shown to have only modest influence. Significant effects are exerted by packing density and physicalmechanical properties of the phases, whereby the ITZ takes up a major position.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001602966
|
oai_dc
|
Crack constitutive model for the prediction of punching failure modes of fiber reinforced concrete laminar structures
|
Crack constitutive model for the prediction of punching failure modes of fiber reinforced concrete laminar structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"A. Ventura-Gouveia(Polytechnic Institute of Viseu); Joaquim A.O. Barros(University of Minho); Álvaro F.M. Azevedo(University of Porto)"
] |
The capability of a multi-directional fixed smeared crack constitutive model to simulate the flexural/punching failure modes of fiber reinforced concrete (FRC) laminar structures is discussed. The constitutive model is implemented in a computer program based on the finite element method, where the FRC laminar structures were simulated according to the Reissner-Mindlin shell theory. The shell is discretized into layers for the simulation of the membrane, bending and out-of-plane shear nonlinear behavior. A stress-strain softening diagram is proposed to reproduce, after crack initiation, the evolution of the normal crack component. The in-plane shear crack component is obtained using the concept of shear retention factor, defined by a crack-strain dependent law. To capture the punching failure mode, a softening diagram is proposed to simulate the decrease of the out-of-plane shear stress components with the increase of the corresponding shear strain components, after crack initiation. With this relatively simple approach, accurate predictions of the behavior of FRC structures failing in bending and in shear can be obtained. To assess the predictive performance of the model, a punching experimental test of a module of a façade panel fabricated with steel fiber reinforced self-compacting concrete is numerically simulated. The influence of some parameters defining the softening diagrams is discussed.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001602965
|
oai_dc
|
Nonlinear finite element analysis of RC beams strengthened with CFRP strip against shear
|
Nonlinear finite element analysis of RC beams strengthened with CFRP strip against shear
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Nalan Bulut(Gazi University); Özgür Anil(Gazi University); Çagatay M. Belgin(Gazi University)"
] |
Strengthening of reinforced concrete (RC) members against shear that is one of the failure modes especially avoided by using carbon fiber reinforced polymer (CFRP) is widely used technique, which is studied at many experimental studies. However, conducting experimental studies are required more financial resources and laboratory facilities. In addition, along with financial resources, more time is needed in order to carry out comprehensive experimental studies. For these reasons, a verified finite element model that is tested with previous experimental studies can be used for reaching generalized results and investigating parameters that are not studied. For this purpose, previous experimental study results are used and “T” cross-sectioned RC beams strengthened with CFRP strips with insufficient shear strength are modeled by using ANSYS software. First, finite elements modeling of the previously tested RC beams are done, and then the computed results are compared with the experimental ones whether they are matched or not. As a result, the finite element model is verified. Later, analyses of the cases without any test results are done by using the verified model. Optimum CFRP strip spacing is determined with this verified finite element model, and compared with the experimental findings.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001574022
|
oai_dc
|
Minimum deformability design of high-strength concrete beams in non-seismic regions
|
Minimum deformability design of high-strength concrete beams in non-seismic regions
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"J.C.M. Ho(The University of Hong Kong); K.J.H. Zhou(The University of Hong Kong)"
] |
In the design of reinforced concrete (RC) beams, apart from providing adequate strength, it is also necessary to provide a minimum deformability even for beams not located in seismic regions. In most RC design codes, this is achieved by restricting the maximum tension steel ratio or neutral axis depth. However, this empirical deemed-to-satisfy method, which was developed based on beams made of normal-strength concrete (NSC) and normal-strength steel (NSS), would not provide a consistent deformability to beams made of high-strength concrete (HSC) and/or high-strength steel (HSS). More critically, HSC beams would have much lower deformability than that provided previously to NSC beams. To ensure that a consistent deformability is provided to all RC beams, it is proposed herein to set an absolute minimum rotation capacity to all RC beams in the design. Based on this requirement, the respective maximum limits of tension steel ratio and neutral axis depth for different concrete and steel yield strengths are derived based on a formula developed by the authors. Finally for incorporation into design codes, simplified guidelines for designing RC beams having the proposed minimum deformability are developed.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001574006
|
oai_dc
|
A constitutive model for fiber-reinforced extrudable fresh cementitious paste
|
A constitutive model for fiber-reinforced extrudable fresh cementitious paste
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Xiangming Zhou(Brunel University); Zongjin Li(The Hong Kong University of Science)"
] |
In this paper, time-continuous constitutive equations for strain rate-dependent materials are presented first, among which those for the overstress and the consistency viscoplastic models are considered. By allowing the stress states to be outside the yield surface, the overstress viscoplastic model directly defines the flow rule for viscoplastic strain rate. In comparison, a rate-dependent yield surface is defined in the consistency viscoplastic model, so that the standard Kuhn-Tucker loading/unloading condition still remains true for rate-dependent plasticity. Based on the formulation of the consistency viscoplasticity, a computational elasto-viscoplastic constitutive model is proposed for the short fiber-reinforced fresh cementitious paste for extrusion purpose. The proposed constitutive model adopts the von-Mises yield criterion, the associated flow rule and nonlinear strain rate-hardening law. It is found that the predicted flow stresses of the extrudable fresh cementitious paste agree well with experimental results. The rate-form constitutive equations are then integrated into an incremental formulation, which is implemented into a numerical framework based on ANSYS/LS-DYNA finite element code. Then, a series of upsetting and ram extrusion processes are simulated. It is found that the predicted forming load-time data are in good agreement with experimental results, suggesting that the proposed constitutive model could describe the elasto-viscoplastic behavior of the short fiber-reinforced extrudable fresh cementitious paste.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001574012
|
oai_dc
|
A mesoscale model for concrete to simulate mechanical failure
|
A mesoscale model for concrete to simulate mechanical failure
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jörg F. Unger(Bauhaus University Weimar); Stefan Eckardt(Bauhaus University Weimar); Carsten Könke(Bauhaus University Weimar)"
] |
In this paper, a mesoscale model of concrete is presented, which considers particles, matrix material and the interfacial transition zone (ITZ) as separate constituents. Particles are represented as ellipsoides, generated according to a prescribed grading curve and placed randomly into the specimen. In this context, an efficient separation procedure is used. The nonlinear behavior is simulated with a cohesive interface model for the ITZ and a combined damage/plasticity model for the matrix material. The mesoscale model is used to simulate a compression and a tensile test. Furthermore, the influence of the particle distribution on the loaddisplacement curve is investigated.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001574024
|
oai_dc
|
Flexural ductility and deformability of reinforced and prestressed concrete sections
|
Flexural ductility and deformability of reinforced and prestressed concrete sections
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Francis T.K. Au(The University of Hong Kong); Cliff C.Y. Leung(The University of Hong Kong); Albert K.H. Kwan(The University of Hong Kong)"
] |
In designing a flexural member for structural safety, both the flexural strength and ductility have to be considered. For this purpose, the flexural ductility of reinforced concrete sections has been studied quite extensively. As there have been relatively few studies on the flexural ductility of prestressed concrete sections, it is not well understood how various structural parameters affect the flexural ductility. In the present study, the full-range flexural responses of reinforced and prestressed concrete sections are analyzed taking into account the nonlinearity and stress-path dependence of constitutive materials. From the numerical results, the effects of steel content, yield strength and degree of prestressing on the yield curvature and ultimate curvature are evaluated. It is found that whilst the concept of flexural ductility in terms of the ductility factor works well for reinforced sections, it can be misleading when applied to prestressed concrete sections. For prestressed concrete sections, the concept of flexural deformability in terms of ultimate curvature times overall depth of section may be more appropriate.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001574008
|
oai_dc
|
Feasibility of utilizing oven-drying test to estimate the durability performance of concrete
|
Feasibility of utilizing oven-drying test to estimate the durability performance of concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"How-Ji Chen(Cheng-Shiu University); Hsien-Sheng Peng(Cheng-Shiu University); Chao-Wei Tang(Cheng-Shiu University)"
] |
The increasing concern for reinforced concrete structure durability has been justifying in many ways in the last few decades. However, there is no perfect durability test method till now. In this research an alternative method, which is based on the cumulative moisture loss percent of the concrete specimens after oven-drying, was proposed to estimate the durability performance of the concrete. Two temperatures were considered for the oven-drying tests: 100°C and 200°C. Test results showed that oven-drying at 200°C was obviously an unsuitable procedure to preserve the fragile microstructure of cement-based materials. By contrast, experimental results through oven-drying at 100°C allowed estimating the moisture loss percent of cement-based materials in a more rational manner. Moreover, the magnitudes of the cumulative moisture loss percent obtained from oven-drying tests at 100°C for 48 hours have good correlations with the data of other well-known methods, namely, electrical resistance test, water permeability test, and mercury intrusion porosimetry test. This investigation established that regarding the oven-drying test as one of the tests for evaluating the potential durability of concrete is considerably practicable.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001574015
|
oai_dc
|
Thermal stress and pore pressure development in microwave heated concrete
|
Thermal stress and pore pressure development in microwave heated concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"A. Akbarnezhad(National University of Singapore); K.C.G. Ong(National University of Singapore)"
] |
Most previous studies have generally overlooked the contribution of thermal stresses generated within the concrete mass when subjected to microwave heating and reported on pore-pressure as being the dominant cause of surface spalling. Also, the variation in electromagnetic properties of concrete and its effects on the microwave heating process have not been studied in detail. In this paper, finite element modeling is used to examine the simultaneous development of compressive thermal stresses and porepressure arising from the microwave heating of concrete. A modified Lambert’s Law formulation is proposed to estimate the microwave power dissipation in the concrete mass. Moreover, the effects of frequency and concrete water content on the concrete heating rate and pattern are investigated. Results show high compressive stresses being generated especially in concrete with a high water content when heated by microwaves of higher frequencies. The results also reveal that the water content of concrete plays a crucial role in the microwave heating process.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001574023
|
oai_dc
|
Investigation of bond behavior between lightweight aggregate concrete and steel rebar using bending test
|
Investigation of bond behavior between lightweight aggregate concrete and steel rebar using bending test
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Mehmet Emin Arslan(Karadeniz Technical University); Ahmet Durmu(Karadeniz Technical University)"
] |
This paper investigates bond behavior of structural lightweight concrete (SLWC) and ordinary concrete (OC) comparatively using bending test called Standard Belgium Hinged Beam Test (SBHBT). For this purpose the experiments were carried out as three series on 36 beam specimens (12 specimens of SLWC and OC with 20φ development length, 12 specimens of SLWC with 25φ development length). For each series bond behavior of steel rebars with 8, 10, 12, 14 mm diameters were tested. The results indicate that bond strength of SLWC is considerable lower than OC and 20φ development length is insufficient for steel rebars with 12 mm and 14 mm diameters. Therefore development length of SLWC was extended to 25φ, even if 8 and 10 mm steel rebars provided acceptable bond strength. In this way, bond strength between SLWC and 8 and 10 mm steel rebars was developed. In addition, adequate bond behavior was achieved for 12 mm rebar but the beam in which 14 mm rebar used exceeded their bearing capacity by shear forces before yield stress. This result shows that SBHBT is more convenient for small sized steel rebars.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001608489
|
oai_dc
|
Size-effect of fracture parameters for crack propagation in concrete: a comparative study
|
Size-effect of fracture parameters for crack propagation in concrete: a comparative study
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Shailendra Kumar(National Institute of Technology); S.V. Barai(Indian Institute of Technology)"
] |
The size-effect study of various fracture parameters obtained from two parameter fracture model, effective crack model, double-K fracture model and double-G fracture model is presented in the paper. Fictitious crack model (FCM) for three-point bend test geometry for cracked concrete beam of laboratory size range 100-400 mm is developed and the different fracture parameters from size effect model, effective crack model, double-K fracture model and double-G fracture model are evaluated using the input data obtained from FCM. In addition, the fracture parameters of two parameter fracture model are obtained using the mathematical coefficients available in literature. From the study it is concluded that the fracture parameters obtained from various nonlinear fracture models including the double-K and double-G fracture models are influenced by the specimen size. These fracture parameters maintain some definite interrelationship depending upon the specimen size and relative size of initial notch length.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001608492
|
oai_dc
|
A numerical study on the damage of projectile impact on concrete targets
|
A numerical study on the damage of projectile impact on concrete targets
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Gang Lu(Shaw Stone & Webster Nuclear); Xibing Li(Central South University); Kejin Wang(Iowa State University)"
] |
This paper presents the numerical simulation of the rigid 12.6 mm diameter kinetic energy ogive-nosed projectile impact on plain and fiber reinforced concrete (FRC) targets with compressive strengths from 45 to 235 MPa, using a three-dimensional finite element code LS-DYNA. A combined dynamic constitutive model, describing the compressive and tensile damage of concrete, is implemented. A modified Johnson_Holmquist_Cook (MJHC) constitutive relationship and damage model are incorporated to simulate the concrete behavior under compression. A tensile damage model is added to the MJHC model to analyze the dynamic fracture behavior of concrete in tension, due to blast loading. As a consequence, the impact damage in targets made of plain and fiber reinforced concrete with same matrix material under same impact velocities (650 m/s) are obtained. Moreover, the damage distribution of concrete after penetration is procured to compare with the experimental results. Numerical simulations provide a reasonable prediction on concrete damage in both compression and tension.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001608542
|
oai_dc
|
Determination of representative volume element in concrete under tensile deformation
|
Determination of representative volume element in concrete under tensile deformation
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"L/ . Skarz· yn´ski(Gdan´ sk University of Technology,); J. Tejchman(Gdan´ sk University of Technology)"
] |
The 2D representative volume element (RVE) for softening quasi-brittle materials like concrete is determined. Two alternative methods are presented to determine a size of RVE in concrete subjected to uniaxial tension by taking into account strain localization. Concrete is described as a heterogeneous threephase material composed of aggregate, cement matrix and bond. The plane strain FE calculations of strain localization at meso-scale are carried out with an isotropic damage model with non-local softening.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001608546
|
oai_dc
|
Evaluation of behavior and strength of prestressed concrete deep beams using nonlinear analysis
|
Evaluation of behavior and strength of prestressed concrete deep beams using nonlinear analysis
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"김태훈((주)삼성물산 건설부문); 천주현(성균관대학교); 신현목(성균관대학교)"
] |
The purpose of this study is to evaluate the behavior and strength of prestressed concrete deep beams using nonlinear analysis. By using a sophisticated nonlinear finite element analysis program, the accuracy and objectivity of the assessment process can be enhanced. A computer program, the RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), was used for the analysis of reinforced concrete structures. Tensile, compressive and shear models of cracked concrete and models of reinforcing and prestressing steel were used to account for the material nonlinearity of prestressed concrete. The smeared crack approach was incorporated. A bonded or unbonded prestressing bar element is used based on the finite element method, which can represent the interaction between the prestressing bars and concrete of a prestressed concrete member. The proposed numerical method for the evaluation of behavior and strength of prestressed concrete deep beams is verified by comparing its results with reliable experimental results.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001608545
|
oai_dc
|
Fracture process of rubberized concrete by fictitious crack model and AE monitoring
|
Fracture process of rubberized concrete by fictitious crack model and AE monitoring
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chao Wang(Hohai University); Zhe Zhao(Southeast University); Yamei Zhang(Southeast University)"
] |
According to the results of three-point bending tests of rubberized concrete and plain concrete, the parameters such as total fracture energy (GF), initial fracture energy (Gf), and tensile strength (ft) are obtained for concrete material. Using ABAQUS software and a bilinear softening fictitious crack model, the crack propagation process was simulated and compared to the experimental results. It is found that the increase of AE hit count has a similar trend with the increase of energy dissipation in FEM simulation. For two types of concretes, both experimental results and numerical simulation indicate that the rubberized concrete has a better fracture resistance.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001491739
|
oai_dc
|
2D evaluation of crack openings using smeared and embedded crack models
|
2D evaluation of crack openings using smeared and embedded crack models
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"André Luís Gamino(University of Campinas); Osvaldo Luís Manzoli(UNESP - Univ Estadual Paulista); José Luiz Antunes de Oliveira e Sousa(University of Campinas); Túlio Nogueira Bittencourt(University of São Paulo)"
] |
This work deals with the determination of crack openings in 2D reinforced concrete structures using the Finite Element Method with a smeared rotating crack model or an embedded crack model. In the smeared crack model, the strong discontinuity associated with the crack is spread throughout the finite element. As is well known, the continuity of the displacement field assumed for these models is incompatible with the actual discontinuity. However, this type of model has been used extensively due to the relative computational simplicity it provides by treating cracks in a continuum framework, as well as the reportedly good predictions of reinforced concrete members’ structural behavior. On the other hand, by enriching the displacement field within each finite element crossed by the crack path, the embedded crack model is able to describe the effects of actual discontinuities (cracks). This paper presents a comparative study of the abilities of these 2D models in predicting the mechanical behavior of reinforced concrete structures. Structural responses are compared with experimental results from the literature, including crack patterns, crack openings and rebar stresses predicted by both models.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001491844
|
oai_dc
|
Modelling creep of high strength concrete
|
Modelling creep of high strength concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"D. Dias-da-Costa(University of Coimbra); E.N.B.S. Júlio(University of Coimbra)"
] |
Recent developments in concrete mixing made possible the production of concretes with high compressive strength showing, simultaneously, high workability. These concretes also present high strengths at young ages, allowing the application of loads sooner. It is of fundamental importance to verify if creep models developed for current concrete still apply to these new concretes. First, a FEM-based software was adopted to test available creep models, most used for normal strength concrete, considering examples with known analytical results. Several limitations were registered, resulting in an incorrect simulation of threedimensional creep. Afterwards, it was implemented a Kelvin-chain algorithm allowing the use of a chosen number of elements, which adequately simulated the adopted examples. From the comparison between numerical and experimental results, it was concluded that the adopted algorithm can be used to model creep of high strength concrete, if the material properties are previously experimentally assessed.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001491839
|
oai_dc
|
Investigation of short column effect of RC buildings: failure and prevention
|
Investigation of short column effect of RC buildings: failure and prevention
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ismail H. Cagatay(Cukurova University); Caner Beklen(); Khalid M. Mosalam(University of California)"
] |
If an infill wall in a reinforced concrete frame is shorter than the column height and there is no initial gap between the column and the infill wall, the short column effect can occur during an earthquake shaking. This form of damage is frequently observed in many earthquake-damaged buildings all around the world and especially in Turkey. In this study, an effective method, which consists of placing additional infill wall segments surrounding the short column, to prevent this type of failure is examined. The influence of adding infill wall in the reduction of the shear force in the short column is also investigated. A parametric study is carried out for one-storey infilled frames with one to five bays using the percentage of the additional infill wall surrounding the short column and the number of spans as the parameters. Then the investigation is extended to a case of a multistorey building damaged due to short column effect during the 1998 Adana-Ceyhan earthquake in Turkey. The results show that the addition of the infill walls around the potential short columns is an effective way to significantly reduce the shear force.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001491852
|
oai_dc
|
Mapping method for elliptical shape loadings on finite element mesh for airport pavement anaysis
|
Mapping method for elliptical shape loadings on finite element mesh for airport pavement anaysis
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"김인태(명지대학교); 이창준(경북대학교 ); 박철우(강원대학교)"
] |
토목공학
| null |
kci_detailed_000098.xml
|
||||
ART001491830
|
oai_dc
|
Quantification of void shape in cemented materials
|
Quantification of void shape in cemented materials
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Okan Önal(Kaynaklar Yerleskesi); Gürkan Özden(Kaynaklar Yerleskesi); Burak Felekoglu(Kaynaklar Yerleskesi)"
] |
A color based segmentation procedure and a modified signature technique have been applied to the detection and analyses of complicated void shapes in cemented materials. The gray-scale segmentation and available signature methods were found to be inefficient especially for the analyses of complicated void shapes. The applicability of the developed methodology has been demonstrated on artificially prepared cemented materials made of self compacted concrete material. In order to characterize the void shapes in the investigated sample images, two new shape parameters called as coefficients of inclusion and exclusion have been proposed. When compared with the traditional use of the signature method, it was found that the methodology followed herein would better characterize complicated void shapes. The methodology followed in this study may be applied to the analysis of complicated void shapes that are often encountered in other cementitious materials such as clays and rocks.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001491759
|
oai_dc
|
Finite element analysis of elastic property of concrete composites with ITZ
|
Finite element analysis of elastic property of concrete composites with ITZ
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Said Abdelmoumen(Universite de Picardie Jules Verne); Brandon Lynge(University of Tulsa); Michele Queneudec-t'Kint(Universite de Picardie Jules Verne); Emmanuel Bellenger(Universite de Picardie Jules Verne)"
] |
For better estimation of elastic property of concrete composites, the effect of Interfacial Transition Zone (ITZ) has been found to be significant. Numerical concrete composites models have been introduced using Finite Element Method (FEM), where ITZ is modeled as a thin shell surrounding aggregate. Therefore, difficulties arise from the mesh generation. In this study, a numerical concrete composites model in 3D based on FEM and random unit cell method is proposed to calculate elastic modulus of concrete composites with ITZ. The validity of the model has been verified by comparing the calculated elastic modulus with those obtained from other analytical and numerical models.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474618
|
oai_dc
|
Modeling of sulfate ionic diffusion in porous cement based composites: effect of capillary size change
|
Modeling of sulfate ionic diffusion in porous cement based composites: effect of capillary size change
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Peter N. Gospodinov(Bulgarian Academy of Sciences)"
] |
The paper considers a theoretical model to study sulfate ion diffusion in saturated porous media - cement based mineral composites, accounting for simultaneous effects, such as filling micro-capillaries (pores) with ions and chemical products and liquid push out of them. Pore volume change and its effect on the distribution of ion concentration within the specimen are investigated. Relations for the distribution of the capillary relative radius and volume within the composite under consideration are found. The numerical algorithm used is further completed to consider capillary size change and the effects accompanying sulfate ion diffusion. Ion distribution within the cross section and volume of specimens fabricated from mineral composites is numerically studied, accounting for the change of material capillary size and volume. Characteristic cases of 2D and 3D diffusion are analyzed. The results found can be used to both assess the sulfate corrosion in saturated systems and predict changes occurring in the pore structure of the composite as a result of sulfate ion diffusion.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474614
|
oai_dc
|
Nonlinear analysis of RC beams strengthened by externally bonded plates
|
Nonlinear analysis of RC beams strengthened by externally bonded plates
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"이광명(성균관대학교); 박재근(성균관대학교); 신현목(성균관대학교); 박윤제(S & Q Engineering Co, Ltd,)"
] |
External bonding of steel or FRP plates to reinforced concrete (RC) structures has been a popular method for strengthening RC structures; however, unexpected premature failure often occurs due to debonding between the concrete and the epoxy. We proposed a Coulomb criterion with a constant failure surface as the debonding failure criterion for the concrete-epoxy interface. Diagonal shear bonding tests were conducted to determine the debonding properties that were related to the failure criterion, such as the angle of internal friction and the coefficient of cohesion. In addition, an interface element that utilized the Coulomb criterion was implemented in a nonlinear finite element analysis program to simulate debonding failure behavior. Experimental studies and numerical analysies on RC beams strengthened by an externally bonded steel or FRP plate were used to determine the range of the coefficient of cohesion. The results that were presented prove that premature failure loads of strengthened RC beams can be predicted with using the bonding properties and the finite element program with including the proposed Coulomb criterion.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474609
|
oai_dc
|
A direct XFEM formulation for modeling of cohesive crack growth in concrete
|
A direct XFEM formulation for modeling of cohesive crack growth in concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"J. L. Asferg(Technical University of Denmark); P. N. Poulsen(Technical University of Denmark); L. O. Nielsen(Technical University of Denmark)"
] |
Applying a direct formulation for the enrichment of the displacement field an extended finite element (XFEM) scheme for modeling of cohesive crack growth is developed. Only elements cut by the crack is enriched and the scheme fits within the framework of standard FEM code. The scheme is implemented for the 3-node constant strain triangle (CST) and the 6-node linear strain triangle (LST). Modeling of standard concrete test cases such as fracture in the notched three point beam bending test (TPBT) and in the four point shear beam test (FPSB) illustrates the performance. The XFEM results show good agreement with results obtained by applying standard interface elements in FEM and with experimental results. In conjunction with criteria for crack growth local versus nonlocal computation of the crack growth direction is discussed.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474611
|
oai_dc
|
3D material model for nonlinear basic creep of concrete
|
3D material model for nonlinear basic creep of concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jorg Bockhold(ZERNA INGENIEURE)"
] |
A new model predicting the nonlinear basic creep behaviour of concrete structures subjected to high multi-axial stresses is proposed. It combines a model based on the thermodynamic framework of the elasto-plastic continuum damage theory for time-independent material behaviour and a rheological model describing phenomenologically the long-term delayed deformation. Strength increase due to ageing is regarded. The general 3D solution for the creep theory is derived from a rate-type form of the uniaxial formulation by the assumption of associated creep flow and a theorem of energy equivalence. The model is able to reproduce linear primary creep as well as secondary and tertiary creep stages under high compressive stresses. For concrete in tension a simple viscoelastic formulation is applied. The material law is then incorporated into a finite element solution procedure for analysis of reinforced concrete structures. Numerical examples of uniaxial creep tests and concrete members show excellent agreement with experimental results.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474616
|
oai_dc
|
3D nonlinear mixed finite-element analysis of RC beams and plates with and without FRP reinforcement
|
3D nonlinear mixed finite-element analysis of RC beams and plates with and without FRP reinforcement
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"M. Hoque(The University of Manitoba); N. Rattanawangcharoen(The University of Manitoba); A. H. Shah(The University of Manitoba); Y. M. Desai(Indian Institute of Technology Powai)"
] |
Three 3D nonlinear finite-element models are developed to study the behavior of concrete beams and plates with and without external reinforcement by fibre-reinforced plastic (FRP). All three models are formulated based upon the 3D theory of elasticity. The stress model is modified from the element developed by Ramtekkar, et al. (2002) to incorporate material nonlinearity in the formulation. Both transverse stress and displacement components are used as nodal degrees-of-freedom to ensure the continuity of both stress and displacement components between the elements. The displacement model uses only displacement components as nodal degrees-of-freedom. The transition model has both stress and displacement components as nodal degrees-of-freedom on one surface, and only displacement components as nodal degrees-of-freedom on the opposite surface. The transition model serves as a connector between the stress and the displacement models. The developed models are validated by comparing the results of the analyses with an existing experimental result. Parametric studies of the effects of the externally reinforced FRP on the load capacity of reinforced concrete (RC) beams and concrete plates are performed to demonstrate the practicality and the efficiency of the proposed models.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474534
|
oai_dc
|
Finite element analysis of shear critical prestressed SFRC beams
|
Finite element analysis of shear critical prestressed SFRC beams
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Job Thomas(Indian Institute of Science); Ananth Ramaswamy(Indian Institute of Science)"
] |
This study reports the details of the finite element analysis of eleven shear critical partially prestressed concrete T-beams having steel fibers over partial or full depth. Prestressed concrete T-beams having a shear span to depth ratio of 2.65 and 1.59 and failing in the shear have been analyzed using 'ANSYS', The 'ANSYS' model accounts for the nonlinear phenomenon, such as, bond-slip of longitudinal reinforcements, post-cracking tensile stiffness of the concrete, stress transfer across the cracked blocks of the concrete and load sustenance through the bridging of steel fibers at crack interface. The concrete is modeled using 'SOLID65?eight-node brick element, which is capable of simulating the cracking and crushing behavior of brittle materials. The reinforcements such as deformed bars, prestressing wires and steel fibers have been modeled discretely using 'LINK8'-3D spar element. The slip between the reinforcement (rebar, fibers) and the concrete has been modeled using a 'COMBIN39" non-linear spring element connecting the nodes of the "LINK8' element representing the reinforcement and nodes of the 'SOLID65' elements representing the concrete. The "ANSYS' model correctly predicted the diagonal tension failure and shear compression failure of prestressed concrete beams observed in the experiment. The capability of the model to capture the critical crack regions, loads and deflections for various types of shear failures in prestressed concrete beam has been illustrated.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474529
|
oai_dc
|
Nonlinear analysis of prestressed concrete structures considering slip behavior of tendons
|
Nonlinear analysis of prestressed concrete structures considering slip behavior of tendons
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"곽효경(한국과학기술원); 김재홍(울산과학기술대학교); 김선훈(영동대학교)"
] |
A tendon model that can effectively be used in finite element analyses of prestressed concrete (PSC) structures with bonded tendons is proposed on the basis of the bond characteristics between a tendon and its surrounding concrete. Since tensile forces between adjacent cracks are transmitted from a tendon to concrete by bond forces, the constitutive law of a bonded tendon stiffened by grouting is different from that of a bare tendon. Accordingly, the apparent yield stress of an embedded tendon is determined from the bond-slip relationship. The definition of the multi-linear average stress-strain relationship is then obtained through a linear interpolation of the stress difference at the post-yielding stage. Unlike in the case of a bonded tendon, on the other hand, a stress increase beyond the effective prestress in an unbonded tendon is not section-dependent but member-dependent. The tendon stress unequivocally represents a uniform distribution along the length when the friction loss is excluded. Thus, using a strain reduction factor, the modified stress-strain curve of an unbonded tendon is derived by successive iterations. The validity of the proposed two tendon models is verified through correlation studies between analytical and experimental results for PSC beams and slabs.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474514
|
oai_dc
|
Effect of strain ratio variation on equivalent stress block parameters for normal weight high strength concrete
|
Effect of strain ratio variation on equivalent stress block parameters for normal weight high strength concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Prabhat Kumar(Central Building Research Institute)"
] |
Replacement of actual stress distribution in a reinforced concrete (RC) flexural member with a simpler geometrical shape, which maintains magnitude and location of the resultant compressive force, is an acceptable conceptual trick. This concept was originally perfected for normal strength concrete. In recent years, high strength concrete (HSC) has been introduced and widely used in modern construction. The stress block parameters require updating to account for special features of HSC in the design of flexural members. In future, more varieties of concrete may be developed and a corresponding design procedure of RC flexural members will be required. The usual practice is to conduct large number of experiments on various sizes of specimen and then evolve an empirical relation. This paper presents a numerical procedure through which the stress block parameters can be numerically derived for a given strain ratio variation. The material model for concrete is presented and computational procedure is described. This procedure is illustrated with several variations of strain ratio. The advantages of numerical procedure are that it costs less and it can be used with new material models for any new variety of concrete.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474508
|
oai_dc
|
ReliabIlity analysis of containment building subjected to earthquake load using response surface method
|
ReliabIlity analysis of containment building subjected to earthquake load using response surface method
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"이성로(목포대학교)"
] |
The seismic safety of reinforced concrete containment building can be evaluated by probabilistic analysis considering randomness of earthquake, which is more rational than deterministic analysis. In the safety assessment of earthquake-resistant structures by the deterministic theory, it is not easy to consider the effects of random variables but the reliability theory and random vibration theory are useful to assess the seismic safety with considering random effects. The reliability assessment of reinforced concrete containment building subjected to earthquake load includes the structural analysis considering random variables such as load, resistance and analysis method, the definition of limit states and the reliability analysis. The reliability analysis procedure requires much time and labor and also needs to get the high confidence in results. In this study, random vibration analysis of containment building is performed with random variables as earthquake load, concrete compressive strength, modal damping ratio. The seismic responses of critical elements of structure are approximated at the most probable failure point by the response surface method. The response surface method helps to figure out the quantitative characteristics of structural response variability. And the limit state is defined as the failure surface of concrete under multi-axial stress, finally the limit state probability of failure can be obtained simply by first-order second moment method. The reliability analysis for the multiaxial strength limit state and the uniaxial strength limit state is performed and the results are compared with each other. This study concludes that the multiaxial failure criterion is a likely limit state to predict concrete failure strength under combined state of stresses and the reliability analysis results are compatible with the fact that the maximum compressive strength of concrete under biaxial compression state increases.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474523
|
oai_dc
|
VR-based education system for inspection of concrete bridges
|
VR-based education system for inspection of concrete bridges
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ayaho Miyamoto(Yamaguchi University); Masa-aki Konno(JIP Techno Science Corporation); Tommi Rissanen(Yamaguchi University)"
] |
In this study, a novel education system for inspection of concrete bridges is presented. The new education approach uses virtual reality (VR) and three-dimensional computer graphics (3DCG) in training engineers to become bridge inspection specialists. The slow time-dependent deterioration of concrete bridges can be reproduced on the computer screen in any chosen time frame, thus providing the trainees with illustrative and educative insight into the deterioration problem. In the proposed VR/3DCG approach a three-dimensional model of concrete bridge, including surfaces, viewpoints and walkthrough paths is created. With the help of this virtual bridge model, an experienced bridge inspection specialist teaches the different deterioration phenomena of concrete bridges to the trainees. The new system was tested, and the inspection results from the case bridge showed that in comparison with the traditional Japanese bridge inspection education system, the new system gives better results. In addition to the improvement of quality of bridge inspections, the new VR/3DCG system-based education brings along some other, more intangible benefits.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474714
|
oai_dc
|
Study on durability of densified high-performance lightweight aggregate concrete
|
Study on durability of densified high-performance lightweight aggregate concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"H. Y. Wang(National Kaohsiung University of Applied Science)"
] |
The densified mixture design algorithm (DMDA) was employed to manufacture high-performance lightweight concrete (LWAC) using silt dredged from reservoirs in southern Taiwan. Dredged silt undergoing hydration and high-temperature sintering was made into a lightweight aggregate for concrete mixing. The workability and durability of the resulting concrete were examined. The LWAC made from dredged silt had high flowability, which implies good workability. Additionally, the LWAC also had good compressive strength and anti-corrosion properties, high surface electrical resistivity and ultrasonic pulse velocity as well as low chloride penetration, all of which are indicators of good durability.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474711
|
oai_dc
|
Investigation on correlation between pulse velocity and compressive strength of concrete using ANNs
|
Investigation on correlation between pulse velocity and compressive strength of concrete using ANNs
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chao-Wei Tang(Cheng-Shiu University); Yiching Lin(National Chung Hsing University); Shih-Fang Kuo(National Chung Hsing University)"
] |
The ultrasonic pulse velocity method has been widely used to evaluate the quality of concrete and assess the structural integrity of concrete structures. But its use for predicting strength is still limited since there are many variables affecting the relationship between strength and pulse velocity of concrete. This study is focused on establishing a complicated correlation between known input data, such as pulse velocity and mixture proportions of concrete, and a certain output (compressive strength of concrete) using artificial neural networks (ANN). In addition, the results predicted by the developed multilayer perceptrons (MLP) networks are compared with those by conventional regression analysis. The result shows that the correlation between pulse velocity and compressive strength of concrete at various ages can be well established by using ANN and the accuracy of the estimates depends on the quality of the information used to train the network. Moreover, compared with the conventional approach, the proposed method gives a better prediction, both in terms of coefficients of determination and root-mean-square error.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474703
|
oai_dc
|
Nonlinear analysis of RC beams based on simplified moment-curvature relation considering fixed-end rotation
|
Nonlinear analysis of RC beams based on simplified moment-curvature relation considering fixed-end rotation
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"김선필(현대건설 기술개발원)"
] |
A simple analytical procedure to analyze reinforced concrete (RC) beams with cracked section is proposed on the basis of the simplified moment-curvature relations of RC sections. Unlike previous analytical models which result in overestimation of stiffness and underestimation of structural deformations induced from assuming perfect-bond condition between steel and concrete, the proposed analytical procedure considers fixed-end rotation caused by anchorage. Furthermore, the proposed analytical procedure, compared with previous numerical models, promotes effectiveness of analysis by reflecting several factors which can influence nonlinearity of RC structure into the simplified moment-curvature relation. Finally, correlation studies between analytical and experimental results are conducted to establish the applicability of the proposed analytical procedure to the nonlinear analysis of RC structures.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474698
|
oai_dc
|
The effect of fly ash/slag on the property of reactive powder mortar designed by using Fuller's ideal curve and error function
|
The effect of fly ash/slag on the property of reactive powder mortar designed by using Fuller's ideal curve and error function
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"C. L. Hwang(National Taiwan University of Science and Technology); S. L. Hsieh(National Taiwan University of Science and Technology)"
] |
This study is mainly focused on applying Fuller?s ideal gradation curve to theoretically design blended ratio of all solid materials of a reactive powder mortar (RPM), also known as reactive powder concrete (RPC), with the aid of error function, and then to study the effect of fly ash/slag on the performance of RPM. The solid particle is assumed to be spherical particles. Then, the void volume of paste (Vv) and the paste content with specific quality can be obtained. As conclusion, under Fuller?s ideal grading curve, the amount of fly ash/slag mixture is higher than that with silica fume along due to it better filled the void within solid particle and obtains higher packing density.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474700
|
oai_dc
|
Shrinkage analysis of reinforced concrete floors using shrinkage-adjusted elasticity modulus
|
Shrinkage analysis of reinforced concrete floors using shrinkage-adjusted elasticity modulus
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"F. T. K. Au(The University of Hong Kong); C. H. Liu(The University of Hong Kong); P. K. K. Lee( The University of Hong Kong)"
] |
The shrinkage of large reinforced concrete floors often gives rise to cracking problems. To identify the problematic areas, shrinkage movement analysis is often carried out by finite element method with proper creep and shrinkage models using step-by-step time integration. However as the full stress history prior to the time interval considered is necessary, with the increase in the number of time intervals used, the amount of computations increases dramatically. Therefore a new method using the shrinkageadjusted elasticity modulus (SAEM) is introduced so that analysis can be carried out using one single step. Examples are presented to demonstrate its usefulness.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474635
|
oai_dc
|
IBEM analyses on half-cell potential measurement for NDE of rebar corrosion
|
IBEM analyses on half-cell potential measurement for NDE of rebar corrosion
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"경제운(한양대학교); 태성호(한양대학교); 이한승(한양대학교); Yalcin Alver(Kumamoto University); 유조형(한양대학교)"
] |
Corrosion of Reinforcement (rebar) is nondestructively estimated by the half-cell potential measurement. As is the case with other nondestructive testings (NDT), understanding of the underlying principles should be clarified in order to obtain meaningful results. Therefore, the measurement of potentials in concrete is analytically investigated. The effect of internal defects on the potentials measured is clarified numerically by the boundary element method (BEM). Thus, a simplified inversion by BEM is applied to convert the potentials on concrete surface to those on rebars, taking into account the concrete resistivity. Because the potentials measured on concrete surface are so sensitive to moisture content, concrete resistivity and surface condition, an inverse procedure to convert the potentials on concrete surface into those on rebars is developed on the basis of BEM. It is found that ASTM criterion is practically applicable to estimate corrosion from the potential values converted. In experiments, an applicability of the procedure is examined by accelerated corrosion tests of reinforced concrete (RC) slabs. For practical use, the procedure is developed where results of IBEM are visualized by VRML (Virtual Reality modeling Language) in three-dimensional space.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474637
|
oai_dc
|
Application of support vector regression for the prediction of concrete strength
|
Application of support vector regression for the prediction of concrete strength
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"이종재(세종대학교); 김두기(군산대학교); 장성규(군산대학교); 이장호(군산대학교)"
] |
The compressive strength of concrete is a commonly used criterion in producing concrete. However, the test on the compressive strength is complicated and time-consuming. More importantly, since the test is usually performed 28 days after the placement of the concrete at the construction site, it is too late to make improvements if unsatisfactory test results are incurred. Therefore, an accurate and practical strength estimation method that can be used before the placement of concrete is highly desirable. In this study, the estimation of the concrete strength is performed using support vector regression (SVR) based on the mix proportion data from two ready-mixed concrete companies. The estimation performance of the SVR is then compared with that of neural network (NN). The SVR method has been found to be very efficient in estimation accuracy as well as computation time, and very practical in terms of training rather than the explicit regression analyses and the NN techniques.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474629
|
oai_dc
|
Limit state assessment of nodal zone capacity in strut-and-tie models
|
Limit state assessment of nodal zone capacity in strut-and-tie models
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Tjen N. Tjhin(Buckland & Taylor Ltd.); Daniel A. Kuchma(University of Illinois at Urbana-Champaign)"
] |
A method based on the lower-bound theorem of limit analysis is presented for the capacity assessment of nodal zones in strut-and-tie models. The idealized geometry of the nodal zones is formed by the intersection of effective widths of the framing struts and ties. The stress distribution is estimated by dividing the nodal zones into constant stress triangles separated by lines of stress discontinuity. The strength adequacy is verified by comparing the biaxial stress field in each triangle with the corresponding failure criteria. The approach has been implemented in a computer-based strut-and-tie tool called CAST (Computer-Aided Strut-and-Tie). An application example is also presented to illustrate the approach.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474633
|
oai_dc
|
Mechanisms of sulfate ionic diffusion in porous cement based composites
|
Mechanisms of sulfate ionic diffusion in porous cement based composites
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"P. Gospodinov(Bulgarian Academy of Sciences); M. Mironova(Bulgarian Academy of Sciences); R. Kazandjiev(Bulgarian Academy of Sciences)"
] |
The paper considers a theoretical model for the study of the process of transfer of sulfate ions in saturated porous media - mineral composites. In its turn, the model treats diffusion of sulfate ions into cement based composites, accounting for simultaneous effects such as filling of micro-capillaries with ions and chemical products and liquid push out of them. The proposed numerical algorithm enables one to account for those simultaneous effects, as well as to model the diffusive behavior of separate sections of the considered volume, such as inert fillers. The cases studied illustrate the capabilities of the proposed model and those of the algorithm developed to study diffusion, considering the specimen complex configuration. Computations show that the theoretical assumptions enable one to qualitatively estimate the experimental evidence and the capabilities of the studied composite. The results found can be used to both assess the sulfate corrosion in saturated systems and predict and estimate damage of structures built of cement-based mineral composites.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474640
|
oai_dc
|
Shape optimization of steel reinforced concrete beams
|
Shape optimization of steel reinforced concrete beams
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"K. S. Babu Narayan(National Institute of Technology Karnataka); Katta Venkataramana(National Institute of Technology Karnataka)"
] |
Steel reinforced concrete is perhaps the most versatile and widely used construction material. The versatility is attributed to mouldability of concrete to any conceivable shape. The inherent property of cracking of concrete is the reason for its low tensile strength and hence the design approach of RCC sections in flexure adopts the cracked section theory where in concrete in tension zone is ignored. Means, modes and methods of exploitation of concrete strength by conceiving shapes other than rectangular whereby ineffective concrete in tension zone is reduced and incorporated in compression zone where it is effective needs consideration. Shape optimization of beams is attempted in this analytical investigation employing Sequential Unconstrained Minimization Technique (SUMT). The results clearly show that trapezoidal beams happen to be less costlier than their rectangular counterparts, their usage needs serious reconsideration by the designers.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474875
|
oai_dc
|
Numerical simulation of fracture and damage behaviour of concrete at different ages
|
Numerical simulation of fracture and damage behaviour of concrete at different ages
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Nanguo Jin(Zhejiang University); Ye Tian(Zhejiang University); Xianyu Jin(Zhejiang University)"
] |
Based on the experiment results, the damage and fracture behavior of concrete at the ages of 1d, 2d, 7d and 28d, in three-point bending and uniaxial tensile tests, were simulated with a finite element program, ABAQUS. The critical stress intensity factor and the critical crack tip opening displacement (CTODC) of concrete were calculated with effective-elastic crack approach for the three-point bending test of grade C30 concrete. Based on the crack band model, a bilinear strain-softening curve was derived to simulate the LOAD-CMOD curves and LOAD-Displacement curves. In numerical analysis of the uniaxial tension test of concrete of grade C40, the damage and fracture mechanics were combined. The smeared cracking model coupling with damaged variable was adopted to evaluate the onset and development of microcracking of uniaxial tensile specimen. The uniaxial tension test was simulated by invoking the damage plastic model which took both damage and plasticity as inner variables with user subroutines. All the numerical simulated results show good agreement with the experimental results.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474622
|
oai_dc
|
Nonlinear finite element analysis of high strength concrete slabs
|
Nonlinear finite element analysis of high strength concrete slabs
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"M. M. Smadi(Jordan University of Science and Technology); K. A. Belakhdar(Jordan University of Science and Technology)"
] |
A rational three-dimensional nonlinear finite element model is described and implemented for evaluating the behavior of high strength concrete slabs under transverse load. The concrete was idealized by using twenty-nodded isoparametric brick elements with embedded reinforcements. The concrete material modeling allows for normal (NSC) and high strength concrete (HSC), which was calibrated based on experimental data. The behavior of concrete in compression is simulated by an elastoplastic work-hardening model, and in tension a suitable post-cracking model based on tension stiffening and shear retention models are employed. The nonlinear equations have been solved using the incremental iterative technique based on the modified Newton-Raphson method. The FE formulation and material modeling is implemented into a finite element code in order to carry out the numerical study and to predict the behavior up to ultimate conditions of various slabs under transverse loads. The validity of the theoretical formulations and the program used was verified through comparison with available experimental data, and the agreement has proven to be very good. A parametric study has been also carried out to investigate the influence of different material and geometric properties on the behavior of HSC slabs. Influencing factors, such as concrete strength, steel ratio, aspect ratio, and support conditions on the load-deflection characteristics, concrete and steel stresses and strains were investigated.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474877
|
oai_dc
|
Damage classification of concrete structures based on grey level co-occurrence matrix using Haar's discrete wavelet transform
|
Damage classification of concrete structures based on grey level co-occurrence matrix using Haar's discrete wavelet transform
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Shahid Kabir(Universite de Sherbrooke); Patrice Rivard(Universite de Sherbrooke)"
] |
A novel method for recognition, characterization, and quantification of deterioration in bridge components and laboratory concrete samples is presented in this paper. The proposed scheme is based on grey level co-occurrence matrix texture analysis using Haar's discrete wavelet transform on concrete imagery. Each image is described by a subset of band-filtered images containing wavelet coefficients, and then reconstructed images are employed in characterizing the texture, using grey level co-occurrence matrices, of the different types and degrees of damage: map-cracking, spalling and steel corrosion. A comparative study was conducted to evaluate the efficiency of the supervised maximum likelihood and unsupervised K-means classification techniques, in order to classify and quantify the deterioration and its extent. Experimental results show both methods are relatively effective in characterizing and quantifying damage; however, the supervised technique produced more accurate results, with overall classification accuracies ranging from 76.8% to 79.1%.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474623
|
oai_dc
|
Mechanical behaviors of concrete combined with steel and synthetic macro-fibers
|
Mechanical behaviors of concrete combined with steel and synthetic macro-fibers
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Zongcai Deng(Beijing University of Technology); Jianhui Li(Beijing University of Technology)"
] |
In this paper, hybrid fibers including high elastic modulus steel fiber and low elastic modulus synthetic macro-fiber (HPP) as two elements were used as reinforcement materials in concrete. The flexural toughness, flexural impact and fracture performance of the composites were investigated systematically. Flexural impact strength was analyzed with statistic analyses method; based on ASTM and JSCE method, an improved flexural toughness evaluating method suitable for concrete with synthetic macro-fiber was proposed herein. The experimental results showed that when the total fiber volume fractions () were kept as a constant (=1.5%), compared with single type of steel or HPP fibers, hybrid fibers can significantly improve the toughness, flexural impact life and fracture properties of concrete. Relative residual strength RSI', impact ductile index l and fracture energy GF of concrete combined with hybrid fibers were respectively 66-80%, 5-12 and 121-137 N/m, which indicated that the synergistic effects (or combined effects) between steel fiber and synthetic macro-fiber were good.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474621
|
oai_dc
|
Seismic damage estimation through measurable dynamic characteristics
|
Seismic damage estimation through measurable dynamic characteristics
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"N. Lakshmanan(Structural Engineering Research Centre); B. K. Raghuprasad(Indian Institute of Science); K. Muthumani(Structural Engineering Research Centre); N. Gopalakrishnan(Structural Engineering Research Centre); R. Sreekala(Structural Engineering Research Centre)"
] |
Ductility based design of reinforced concrete structures implicitly assumes certain damage under the action of a design basis earthquake. The damage undergone by a structure needs to be quantified, so as to assess the post-seismic reparability and functionality of the structure. The paper presents an analytical method of quantification and location of seismic damage, through system identification methods. It may be noted that soft ground storied buildings are the major casualties in any earthquake and hence the example structure is a soft or weak first storied one, whose seismic response and temporal variation of damage are computed using a non-linear dynamic analysis program (IDARC) and compared with a normal structure. Time period based damage identification model is used and suitably calibrated with classic damage models. Regenerated stiffness of the three degrees of freedom model (for the three storied frame) is used to locate the damage, both on-line as well as after the seismic event. Multi resolution analysis using wavelets is also used for localized damage identification for soft storey columns.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474604
|
oai_dc
|
Validation of 3D crack propagation in plain concrete. Part I: Experimental investigation - the PCT3D test
|
Validation of 3D crack propagation in plain concrete. Part I: Experimental investigation - the PCT3D test
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"C. Feist(University of Innsbruck); G. Hofstetter(University of Innsbruck)"
] |
The objective of this paper is to provide experimental data on the propagation of curved crack-surfaces and the respective load-displacement diagrams for the validation of numerical models for cracking of concrete, subjected to three-dimensional stress states. To this end beam-shaped specimens are subjected to combined bending and torsional loading, leading to the formation of a spatially curved crack-surface. The experimental data contain the evolution of the load and of the strains at selected points in terms of the crack mouth opening displacement and the propagation of the crack surface.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474599
|
oai_dc
|
Computer-aided approach of parameters influencing concrete service life and field validation
|
Computer-aided approach of parameters influencing concrete service life and field validation
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"V. G. Papadakis(University of Ioannina); M. P. Efstathiou(Patras Science Park S.A.); C. A. Apostolopoulos(University of Patras)"
] |
Over the past decades, an enormous amount of effort has been expended in laboratory and field studies on concrete durability estimation. The results of this research are still either widely scattered in the journal literature or mentioned briefly in the standard textbooks. Moreover, the theoretical approaches of deterioration mechanisms with a predictive character are limited to some complicated mathematical models not widespread in practice. A significant step forward could be the development of appropriate software for computer-based estimation of concrete service life, including reliable mathematical models and adequate experimental data. In the present work, the basis for the development of a computer estimation of the concrete service life is presented. After the definition of concrete mix design and structure characteristics, as well as the consideration regarding the environmental conditions where the structure will be found, the concrete service life can be reliably predicted using fundamental mathematical models that simulate the deterioration mechanisms. The prediction is focused on the basic deterioration phenomena of reinforced concrete, such as carbonation and chloride penetration, that initiate the reinforcing bars corrosion. Aspects on concrete strength and the production cost are also considered. Field observations and data collection from existing structures are compared with predictions of service life using the above model. A first attempt to develop a database of service lives of different types of reinforced concrete structure exposed to varying environments is finally included.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474602
|
oai_dc
|
Tension and impact behaviors of new type fiber reinforced concrete
|
Tension and impact behaviors of new type fiber reinforced concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Zongcai Deng(Beijing University of Technology); Jianhui Li(Beijing University of Technology)"
] |
This paper is concentrated on the behaviors of five different types of fiber reinforced concrete (FRC) in uniaxial tension and flexural impact. The complete stress-strain responses in tension were acquired through a systematic experimental program. It was found that the tensile peak strains of concrete with micro polyethylene (PEF) fiber are about 18-31% higher than that of matrix concrete, those for composite with macro polypropylene fiber is 40-83% higher than that of steel fiber reinforced concrete (SFRC). The fracture energy of composites with micro-fiber is 23-67% higher than that of matrix concrete; this for macro polypropylene fiber and steel fiber FRCs are about 150-210% and 270-320% larger than that of plain concrete respectively. Micro-fiber is more effective than macro-fiber for initial crack impact resistance; however, the failure impact resistance of macro-fiber is significantly larger than that of micro-fiber, especially macro-polypropylene-fiber.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474603
|
oai_dc
|
Numerical modeling of slipforming operations
|
Numerical modeling of slipforming operations
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"M. Lachemi(Ryerson University); R. Elimov(Ryerson University)"
] |
Slipforming is a construction method in which the forms move continuously during concrete placement. This paper presents a numerical procedure based on the finite element method to simulate the thermal behavior of concrete during slipforming operations. The validity of the model was successfully tested by simulating a very complex but well documented field case of actual slipforming operations performed during the construction of an offshore concrete oil platform structure. The results obtained have been related to the shape of the concrete ?hardened front? in the forms, which allows quick evaluation of the operation. The results of the numerical investigation have shown that the shape of the hardened front? can be affected by the temperature of the fresh concrete and ambient conditions. For a given initial concrete temperature, there are limitations for the ambient temperature that, when exceeded, can create an unfavorable shape of the concrete ?hardened front? in the forms. Similarly, for a given ambient temperature,the initial concrete temperature should not be fall below an established limit in order to avoid unfavorable shape of the ?hardened front?.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474606
|
oai_dc
|
Validation of 3D crack propagation in plain concrete. Part II: Computational modeling and predictions of the PCT3D test
|
Validation of 3D crack propagation in plain concrete. Part II: Computational modeling and predictions of the PCT3D test
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"T. Christian Gasser(Royal Institute of Technology (KTH))"
] |
The discrete crack-concept is applied to study the 3D propagation of tensile-dominated failure in plain concrete. To this end the Partition of Unity Finite Element Method (PUFEM) is utilized and the strong discontinuity approach is followed. A consistent linearized implementation of the PUFEM is combined with a predictor-corrector algorithm to track the crack path, which leads to a robust numerical description of concrete cracking. The proposed concept is applied to study concrete failure during the PCT3D test and the predicted numerical results are compared to experimental data. The proposed numerical concept provides a clear interface for constitutive models and allows an investigation of their impact on concrete cracking under 3D conditions, which is of significant scientific interests to interpret results from 3D experiments.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474575
|
oai_dc
|
Time dependent equations for the compressive strength of self-consolidating concrete through statistical \r\noptimization
|
Time dependent equations for the compressive strength of self-consolidating concrete through statistical \r\noptimization
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"K. M. A. Hossain(Ryerson University); M. Lachemi(Ryerson University)"
] |
Self-consolidating concrete (SCC) in the fresh state is known for its excellent deformability, high resistance to segregation, and use, without applying vibration, in congested reinforced concrete structures characterized by difficult casting conditions. Such a concrete can be obtained by incorporating either mineral or chemical admixtures. This paper presents the results of an investigation to asses the applicability of Abram뭩 law in predicting the compressive strength of SCC to any given age. Abram's law is based on the assumption that the strength of concrete with a specific type of aggregate at given age cured at a prescribed temperature depends primarily on the water-to-cement ratio (W/C). It is doubtful that such W/C law is applicable to concrete mixes with mineral or chemical admixtures as is the case for SCC where water to binder ratio (W/B) is used instead of W/C as the basis for mix design. Strength data of various types of SCC mixtures is collected from different sources to check the performance of Abram's law. An attempt has been made to generalize Abram's law by using various optimization methodologies on collected strength data of various SCC mixtures. A set of generalized equations is developed for the prediction of SCC strength at various ages. The performance of generalized equations is found better than original Abram's equations.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474571
|
oai_dc
|
Saw-tooth softening/stiffening - a stable computational procedure for RC
|
Saw-tooth softening/stiffening - a stable computational procedure for RC
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jan G. Rots(University of Technology); Stefano Invernizzi(Politecnico di Torino); Beatrice Belletti(University of Parma)"
] |
Over the past years techniques for non-linear analysis have been enhanced significantly via improved solution procedures, extended finite element techniques and increased robustness of constitutive models. Nevertheless, problems remain, especially for real world structures of softening materials like concrete. The softening gives negative stiffness and risk of bifurcations due to multiple cracks that compete to survive. Incremental-iterative techniques have difficulties in selecting and handling the local peaks and snap-backs. In this contribution, an alternative method is proposed. The softening diagram of negative slope is replaced by a saw-tooth diagram of positive slopes. The incremental-iterative Newton method is replaced by a series of linear analyses using a special scaling technique with subsequent stiffness/strength reduction per critical element. It is shown that this event-by-event strategy is robust and reliable. First, the model is shown to be objective with respect to mesh refinement. Next, the example of a large-scale dog-bone specimen in direct tension is analyzed using an isotropic version of the saw-tooth model. The model is capable of automatically providing the snap-back response. Subsequently, the saw-tooth model is extended to include anisotropy for fixed crack directions to accommodate both tensile cracking and compression strut action for reinforced concrete. Three different reinforced concrete structures are analyzed, a tension-pull specimen, a slender beam and a slab. In all cases, the model naturally provides the local peaks and snap-backs associated with the subsequent development of primary cracks starting from the rebar. The secant saw-tooth stiffness is always positive and the analysis always 멵onverges? Bifurcations are prevented due to the scaling technique.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474576
|
oai_dc
|
Effect of axial load on flexural behaviour of cyclically loaded RC columns
|
Effect of axial load on flexural behaviour of cyclically loaded RC columns
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"F. T. K. Au(The University of Hong Kong); Z. Z. Bai(The University of Hong Kong)"
] |
The flexural behaviour of symmetrically reinforced concrete (RC) columns cast of normal- and high-strength concrete under both monotonic and cyclic loading is studied based on an analytical procedure, which employs the actual stress-strain curves and takes into account the stress-path dependence of concrete and steel reinforcement. The analysis is particularly extended into the post-peak stage with large inelastic deformation at various applied axial load level. The effect of axial load on their complete flexural behaviour is then identified based on the results obtained. The axial load is found to have fairly large effect on the flexural behaviour of RC columns under both monotonic and cyclic loading. Such effects are discussed through examination of various aspects including the moment-curvature relationship, moment capacity, flexural ductility, variation of neutral axis depth and steel stress.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474570
|
oai_dc
|
Material modeling of steel fiber reinforced concrete
|
Material modeling of steel fiber reinforced concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"B. Thomee(Technische Universitat Munchen); K. Schikora(Technische Universitat Munchen); K.-U. Bletzinger(Technische Universitat Munchen)"
] |
Modeling of physically non-linear behavior becomes more and more important for the analysis of SFRC structures in practical applications. From this point of view we will present an effective, three-dimensional constitutive model for SFRC, that is also easy to implement in commercial finite element programs. Additionally, the finite element analysis should only require standard material parameters which can be gained easily from conventional experiments or which are specified in appropriate building codes. Another important point is attaining the material parameters from experimental data. The procedures to determine the material parameters proposed in appropriate codes seem to be only approximations and are unsuitable for precise structural analysis. Therefore a finite element analysis of the test itself is used to get the material parameters. This process is also denoted as inverse analysis. The efficiency of the proposed constitutive model is demonstrated on the basis of numerical examples and their comparison to experimental results. In the framework of material parameter identification the idea of a new, indirect tension testing procedure, the 밠odified Tension Test? is adopted and extended to an easy-to-carry-out tension test for steel fiber reinforced concrete specimens.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474573
|
oai_dc
|
A numerical analysis of compressive strength of\r\nrectangular concrete columns confined by FRP
|
A numerical analysis of compressive strength of\r\nrectangular concrete columns confined by FRP
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Huei-Jeng Lin(National Taiwan University); Chin-I Liao(National Taiwan University); Chin Yang(National Taiwan University)"
] |
This investigation presents an analysis procedure for simulating the compressive behavior of a rectangular concrete column confined by fiber-reinforced plastic (FRP) under uniaxial load. That is, the entire stress-strain curve can be drawn through the present analysis procedure. The modified Mander뭩 stress-strain model (Mander, et al. 1988) and finite element method are adopted in this analysis procedure. The numerical analysis results are compared with the experimental results to verify the accuracy of the analysis procedure. This study offers a useful analysis procedure of researching the compressive behavior of rectangular concrete columns confined by FRP. Two main parameters, the number of FRP layers and the radius of the round corners of a rectangular column, are investigated. The numerical results show that non-uniform stresses occur and reduce the sectional effective area owing to the geometry of the confined rectangular column. The stresses are concentrated at the corners of the rectangular column. Compressive strength of a rectangular column increases greatly because the number of FRP layers increase. The maximum predicted compressive stress of the rectangular column has approximately 10% error as compared to the experimental results. Comparing the numerical and experimental results demonstrates that the accuracy of this analysis procedure is credible. Besides, the stress-strain curves of the R30 models, which are rectangular concrete column with large radius of round corners, are almost bilinear. This calculated results conform to the expectation and show the present analysis procedure are more suitable than Mander뭩 model (1988) to analyze the compressive behavior of the rectangular concrete column confined by FRP.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001479317
|
oai_dc
|
Open-slip coupled model for simulating three-dimensional bond behavior of reinforcing bars in concrete
|
Open-slip coupled model for simulating three-dimensional bond behavior of reinforcing bars in concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Feng Shang(Tsinghua University); Seji Kawai(Tsinghua University); Tetsuya Mishima(Maeda Corporation); Xuhui An(Tsinghua University)"
] |
The bond mechanism for reinforcing bars in concrete is equivalent to the normal contact and friction between the inclined ribs and the surrounding concrete. Based on the contact density model for the computation of shear transfer across cracks, an open-slip coupled model was developed for simulating three-dimensional bond behavior for reinforcing bars in concrete. A parameter study was performed and verified by simulating pull-out experiments of extremely different boundary conditions: short bar embedment with a huge concrete cover, extremely long bar embedment with a huge concrete cover, embedded aluminum bar and short bar embedded length with an insufficient concrete cover. The bar strain effect and splitting of the concrete cover on a local bond can be explained by finite element (FE) analysis. The analysis shows that the strain effect results from a large local slip and the splitting effect of a large opening of the interface. Finally, the sensitivity of rebar geometry was also checked by FE analysis and implies that the open-slip coupled model can be extended to the case of plain bar.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001479327
|
oai_dc
|
Numerical and statistical analysis of permeability of concrete as a random heterogeneous composite
|
Numerical and statistical analysis of permeability of concrete as a random heterogeneous composite
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Kefei Li(Tsinghua University); Chunsheng Zhou(Tsinghua University)"
] |
This paper investigates the concrete permeability through a numerical and statistical approach. Concrete is considered as a random heterogeneous composite of three phases: aggregates, interfacial transition zones (ITZ) and matrix. The paper begins with some classical bound and estimate theories applied to concrete permeability and the influence of ITZ on these bound and estimate values is discussed. Numerical samples for permeability analysis are established through random aggregate structure (RAS) scheme, each numerical sample containing randomly distributed aggregates coated with ITZ and dispersed in a homogeneous matrix. The volumetric fraction of aggregates is fixed and the size distribution of aggregates observes Fuller’s curve. Then finite element method is used to solve the steady permeation problem on 2D numerical samples and the overall permeability is deduced from flux-pressure relation. The impact of ITZ on overall permeability is analyzed in terms of ITZ width and contrast ratio between ITZ and matrix permeabilities. Hereafter, 3680 samples are generated for 23 sample sizes and 4 contrast ratios, and statistical analysis is performed on the permeability dispersion in terms of sample size and ITZ characteristics. By sample theory, the size of representative volume element (RVE) for permeability is then quantified considering sample realization number and expected error. Concluding remarks are provided for the impact of ITZ on concrete permeability and its statistical characteristics.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001479326
|
oai_dc
|
Prediction of ECC tensile stress-strain curves based on modified fiber bridging relations considering fiber distribution characteristics
|
Prediction of ECC tensile stress-strain curves based on modified fiber bridging relations considering fiber distribution characteristics
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Bang Yeon Lee(University of Michigan); 김진근(KAIST); 김윤용(Chungnam National University)"
] |
This paper presents a prediction and simulation method of tensile stress-strain curves of Engineered Cementitious Composites (ECC). For this purpose, the bridging stress and crack opening relations were obtained by the fiber bridging constitutive law which is quantitatively able to consider the fiber distribution characteristics. And then, a multi-linear model is employed for a simplification of the bridging stress and crack opening relation. In addition, to account the variability of material properties, randomly distributed properties drawn from a normal distribution with 95% confidence are assigned to each element which is determined on the basis of crack spacing. To consider the variation of crack spacing, randomly distributed crack spacing is drawn from the probability density function of fiber inclined angle calculated based on sectional image analysis. An equation for calculation of the crack spacing that takes into quantitative consideration the dimensions and fiber distribution was also derived. Subsequently, a series of simulations of ECC tensile stress-strain curves was performed. The simulation results exhibit obvious strain hardening behavior associated with multiple cracking, which correspond well with test results.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001479325
|
oai_dc
|
Nonlinear finite element analysis of effective CFRP bonding length and strain distribution along concrete-CFRP interface
|
Nonlinear finite element analysis of effective CFRP bonding length and strain distribution along concrete-CFRP interface
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ali Baran Dogan(MITENG Engineering Inc.); Ozgur Anil(Gazi University)"
] |
CFRP has been widely used for strengthening reinforced concrete members in last decade. The strain transfer mechanism from concrete face to CFRP is a key factor for rigidity, ductility, energy dissipation and failure modes of concrete members. For these reasons, determination of the effective CFRP bonding length is the most crucial step to achieve effective and economical strengthening. In this paper, generalizations are made on effective bonding length by increasing the amount of test data. For this purpose, ANSYS software is employed, and an experimentally verified nonlinear finite element model is prepared. Special contact elements are utilized along the concrete-CFRP strip interface for investigating stress distribution, load-displacement behavior, and effective bonding length. Then results are compared with the experimental results. The finite element model found consistent results with the experimental findings.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001479319
|
oai_dc
|
Modeling of ion diffusion coefficient in saturated concrete
|
Modeling of ion diffusion coefficient in saturated concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Xiao-Bao Zuo(Southeast University); Wei Sun(Southeast University); Cheng Yu(Southeast University); Xu-Rong Wan(Nanjing University Of Science & Technology)"
] |
This paper utilizes the modified Davis model and the mode coupling theory, as parts of the electrolyte solution theory, to investigate the diffusivity of the ion in concrete. Firstly, a computational model of the ion diffusion coefficient, which is associated with ion species, pore solution concentration, concrete mix parameters including water-cement ratio and cement volume fraction, and microstructure parameters such as the porosity and tortuosity, is proposed in the saturated concrete. Secondly, the experiments, on which the chloride diffusion coefficient is measured by the rapid chloride penetration test,have been carried out to investigate the validity of the proposed model. The results indicate that the chloride diffusion coefficient obtained by the proposed model is in agreement with the experimental result. Finally, numerical simulation has been completed to investigate the effects of the porosity, tortuosity, water-cement ratio, cement volume fraction and ion concentration in the pore solution on the ion diffusion coefficients. The results show that the ion diffusion coefficient in concrete increases with the porosity, water-cement ratio and cement volume fraction, while we see a decrease with the increasing of tortuosity. Meanwhile, the ion concentration produces more obvious effects on the diffusivity itself, but has almost no effects on the other ions.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474589
|
oai_dc
|
Investigations on the tensile strength of high-performance fiber reinforced concrete using statistical methods
|
Investigations on the tensile strength of high-performance fiber reinforced concrete using statistical methods
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"P. Ramadoss(Anna University); K. Nagamani(Anna University)"
] |
This paper presents the investigations towards developing a better understanding on the contribution of steel fibers on the tensile strength of high-performance fiber reinforced concrete (HPFRC). An extensive experimentation was carried out with w/cm ratios ranging from 0.25 to 0.40 and fiber content ranging from zero to 1.5 percent with an aspect ratio of 80. For 32 concrete mixes, flexural and splitting tensile strengths were determined at 28 days. The influence of fiber content in terms of fiber reinforcing index on the flexural and splitting tensile strengths of HPFRC is presented. Based on the test results, mathematical models were developed using statistical methods to predict 28-day flexural and splitting tensile strengths of HPFRC for a wide range of w/cm ratios. The expressions, being developed with strength ratios and not with absolute values of strengths and are applicable to wide range of w/cm ratio and different sizes/shapes of specimens. Relationship between flexural and splitting tensile strengths has been developed using regression analysis and absolute variation of strength values obtained was within 3.85 percent. To examine the validity of the proposed model, the experimental results of previous researchers were compared with the values predicted by the model.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474587
|
oai_dc
|
Elimination of the effect of strain gradient from concrete compressive strength test results
|
Elimination of the effect of strain gradient from concrete compressive strength test results
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Sami W. Tabsh(American University of Sharjah)"
] |
Poor strength test results are sometimes not an indication of low concrete quality, but rather inferior testing quality. In a compression test, the strain distribution over the ends of the specimen is a critical factor for the test results. Non-uniform straining of a concrete specimen leads to locally different compressive stresses on the cross-section, and eventual premature breaking of the specimen. Its effect on a specimen can be quantified by comparing the compressive strength results of two specimens, one subjected to uniform strain and another to a specified strain gradient. This can be done with the help of a function that relates two parameters, the strain ratio and the test efficiency. Such a function depends on the concrete strength and cross-sectional shape of the specimen. In this study, theoretical relationships between the strain ratio and test efficiency are developed using a concrete stress-strain model. The results show that for the same strain ratio, the test efficiency is larger for normal strength concrete than for high strength concrete. Further, the effect of the strain gradient on the test result depends on the cross-sectional shape of the specimen. Implementation of the results is demonstrated with the aid of two examples.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474593
|
oai_dc
|
Numerical modelling and finite element analysis of \r\nstress wave propagation for ultrasonic pulse velocity testing of concrete
|
Numerical modelling and finite element analysis of \r\nstress wave propagation for ultrasonic pulse velocity testing of concrete
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Ismail Ozgur Yaman(Middle East Technical University); Zekai Akbay(DaimlerChrysler AG); Haluk Aktan(Wayne State University)"
] |
Stress wave propagation through concrete is simulated by finite element analysis. The concrete medium is modeled as a homogeneous material with smeared properties to investigate and establish the suitable finite element analysis method (explicit versus implicit) and analysis parameters (element size, and solution time increment) also suitable for rigorous investigation. In the next step, finite element analysis model of the medium is developed using a digital image processing technique, which distinguishes the mortar and aggregate phases of concrete. The mortar and aggregate phase topologies are, then, directly mapped to the finite element mesh to form a heterogeneous concrete model. The heterogeneous concrete model is then used to simulate wave propagation. The veracity of the model is demonstrated by evaluating the intrinsic parameters of nondestructive ultrasonic pulse velocity testing of concrete. Quantitative relationships between aggregate size and testing frequency for nondestructive testing are presented.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474591
|
oai_dc
|
Prediction of chloride ingress into saturated concrete\r\non the basis of a multi-species model by numerical calculations
|
Prediction of chloride ingress into saturated concrete\r\non the basis of a multi-species model by numerical calculations
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"T.Q. Nguyen(Laboratoire Central des Ponts et Chauss?s); V. Baroghel-Bouny(Laboratoire Central des Ponts et Chauss?s); P. Dangla(Laboratoire des Matriaux et Structures du G?ie Civil)"
] |
A multi-species model based on the Nernst-Planck equation has been developed by using a finite volume method. The model makes it possible to simulate transport due to an electrical field or by diffusion and to predict chloride penetration through water saturated concrete. The model is used in this paper to assess and analyse chloride diffusion coefficients and chloride binding isotherms. The experimental assessment of the effective chloride diffusion coefficient consists in measuring the chloride penetration depth by using a colorimetric method. The effective diffusion coefficient determined numerically allows to correctly reproduce the chloride penetration depth measured experimentally. Then, a new approach for the determination of chloride binding, based on non-steady state diffusion tests, is proposed. The binding isotherm is identified by a numerical inverse method from a single experimental total chloride concentration profile obtained at a given exposure time and from Freundlich뭩 formula. In order to determine the initial pore solution composition (required as initial conditions for the model), the method of Taylor that describes the release of alkalis from cement and alkali sorption by the hydration products is used here. Finally, with these input data, prediction of total and water-soluble chloride concentration profiles has been performed. The method is validated by comparing the results of numerical simulations to experimental results obtained on various types of concretes and under different exposure conditions.
|
토목공학
| null |
kci_detailed_000098.xml
|
|||
ART001474597
|
oai_dc
|
Artificial neural network model for the strength prediction of fully restrained RC slabs subjected to membrane action
|
Artificial neural network model for the strength prediction of fully restrained RC slabs subjected to membrane action
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Khandaker M. A. Hossain(Ryerson University); Mohamed Lachemi(Ryerson University); Said M. Easa(Ryerson University)"
] |
This paper develops an artificial neural network (ANN) model for uniformly loaded restrained reinforced concrete (RC) slabs incorporating membrane action. The development of membrane action in RC slabs restrained against lateral displacements at the edges in buildings and bridge structures significantly increases their load carrying capacity. The benefits of compressive membrane action are usually not taken into account in currently available design methods based on yield-line theory. By extending the existing knowledge of compressive membrane action, it is possible to design slabs in building and bridge decks economically with less than normal reinforcement. The processes involved in the development of ANN model such as the creation of a database of test results from previous research studies, the selection of architecture of the network from extensive trial and error procedure, and the training and performance validation of the model are presented. The ANN model was found to predict accurately the ultimate strength of fully restrained RC slabs. The model also was able to incorporate strength enhancement of RC slabs due to membrane action as confirmed from a comparative study of experimental and yield line-based predictions. Practical applications of the developed ANN model in the design process of RC slabs are also highlighted.
|
토목공학
| null |
kci_detailed_000099.xml
|
|||
ART001464235
|
oai_dc
|
Multi-cracking modelling in concrete solved by a modified DR method
|
Multi-cracking modelling in concrete solved by a modified DR method
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Rena C. Yu(Universidad de Castilla-La Mancha); Gonzalo Ruiz(Universidad de Castilla-La Mancha)"
] |
Our objective is to model static multi-cracking processes in concrete. The explicit dynamic relaxation (DR) method, which gives the solutions of non-linear static problems on the basis of the steady-state conditions of a critically damped explicit transient solution, is chosen to deal with the high geometric and material non-linearities stemming from such a complex fracture problem. One of the common difficulties of the DR method is its slow convergence rate when non-monotonic spectral response is involved. A modified concept that is distinct from the standard DR method is introduced to tackle this problem. The methodology is validated against the stable three point bending test on notched concrete beams of different sizes. The simulations accurately predict the experimental load-displacement curves.
The size effect is caught naturally as a result of the calculation. Micro-cracking and non-uniform crack propagation across the fracture surface also come out directly from the 3D simulations.
|
토목공학
| null |
kci_detailed_000099.xml
|
|||
ART001473757
|
oai_dc
|
Finite element analysis of carbon fiber-reinforced\r\npolymer (CFRP) strengthened reinforced concrete beams
|
Finite element analysis of carbon fiber-reinforced\r\npolymer (CFRP) strengthened reinforced concrete beams
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"SangHun Kim(Syracuse University); Riyad S. Aboutaha(Syracuse University)"
] |
This paper presents investigation of a three-dimensional (3-D) nonlinear finite element model analysis to examine the behavior of reinforced concrete beams strengthened with Carbon Fiber Reinforced Polymer (CFRP) composites to enhance the flexural capacity and ductility of the beams. Three-dimensional nonlinear finite element models were developed between the internal reinforcement and concrete using a smeared relationship. In addition, bond models between the concrete surface and CFRP composite were developed using a smeared bond for general analyses and a contact bond for sensitivity analyses. The results of the FEA were compared with the experimental data on full-scale members. The results of two finite-element bonding models showed good agreement with those of the experimental tests.
|
토목공학
| null |
kci_detailed_000099.xml
|
|||
ART001473735
|
oai_dc
|
Analysis of the fracture surface morphology of concrete\r\nby the method of vertical sections Analysis of the fracture surface morphology of concrete\r\nby the method of vertical sections
|
Analysis of the fracture surface morphology of concrete\r\nby the method of vertical sections Analysis of the fracture surface morphology of concrete\r\nby the method of vertical sections
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Janusz Konkol(Rzeszow University of Technology); Grzegorz Prokopski(Rzeszow University of Technology)"
] |
The examinations carried out have confirmed a relationship existing between the character of fracture surfaces and the composition and structure of (basalt and gravel) concretes. For both concretes investigated, a very good correlation was obtained between the profile line development factor, RL, and the fracture surface development factor, RS. With the increase in the RL parameter, the fracture surface development factor RS also increased. Agreement between the proposed relationship of RS = f(RL) and the proposal given by Coster and Chermant (1983) was obtained. Stereological examinations carried out along with fractographic examinations made it possible to obtain a statistical model for the determination of RL (or RS) based on the volume of air voids in concrete, Vair , the specific surface of air pores, the specific surface of coarse aggregate, SVagg., and the volume of mortar, Vm. An effect of coarse aggregate type on the obtained values of the profile line development factor, RL , as well as on the relationship RS = f(RL) was observed. The increment in the fracture surface development factor RS with increasing RL parameter was larger in basalt concretes than in gravel concretes, which was a consequence of the level of complexity of fractures formed, resulting chiefly from the shape of coarse aggregate grains.
|
토목공학
| null |
kci_detailed_000099.xml
|
|||
ART001473803
|
oai_dc
|
Numerical simulations of localization of deformation in quasi-brittle materials within non-local softening plasticity
|
Numerical simulations of localization of deformation in quasi-brittle materials within non-local softening plasticity
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"J. Bobinski(Gdansk University of Technology); J. Tejchman(Gdansk University of Technology)"
] |
The paper presents results of FE-calculations on shear localizations in quasi-brittle materials during both an uniaxial plane strain compression and uniaxial plane strain extension. An elasto-plastic model with a linear Drucker-Prager type criterion using isotropic hardening and softening and non-associated flow rule was used. A non-local extension was applied in a softening regime to capture realistically shear localization and to obtain a well-posed boundary value problem. A characteristic length was incorporated via a weighting function. Attention was focused on the effect of mesh size, mesh alignment, non-local parameter and imperfections on the thickness and inclination of shear localization. Different methods to calculate plastic strain rates were carefully discussed.
|
토목공학
| null |
kci_detailed_000099.xml
|
|||
ART001473788
|
oai_dc
|
Tension stiffening effect of RC panels\r\nsubject to biaxial stresses
|
Tension stiffening effect of RC panels\r\nsubject to biaxial stresses
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Hyo-Gyoung Kwak( KAIST); Do-Yeon Kim(KAIST)"
] |
An analytical model which can simulate the post-cracking nonlinear behavior of reinforced concrete (RC) members such as bars and panels subject to uniaxial and biaxial stresses is presented. The proposed model includes the description of biaxial failure criteria and the average stress-strain relation of reinforcing steel. Based on strain distribution functions of steel and concrete after cracking, a criterion to consider the tension-stiffening effect is proposed using the concept of average stresses and strains. The validity of the introduced model is established by comparing the analytical predictions for reinforced concrete uniaxial tension members with results from experimental studies. In advance, correlation studies between analytical results and experimental data are also extended to RC panels subject to biaxial tensile stresses to verify tAn analytical model which can simulate the post-cracking nonlinear behavior of reinforced concrete (RC) members such as bars and panels subject to uniaxial and biaxial stresses is presented. The proposed model includes the description of biaxial failure criteria and the average stress-strain relation of reinforcing steel. Based on strain distribution functions of steel and concrete after cracking, a criterion to consider the tension-stiffening effect is proposed using the concept of average stresses and strains. The validity of the introduced model is established by comparing the analytical predictions for reinforced concrete uniaxial tension members with results from experimental studies. In advance, correlation studies between analytical results and experimental data are also extended to RC panels subject to biaxial tensile stresses to verify the efficiency of the proposed model and to identify the significance of various effects on the response of biaxially loaded reinforced concrete panels.
he efficiency of the proposed model and to identify the significance of various effects on the response of biaxially loaded reinforced concrete panels.
|
토목공학
| null |
kci_detailed_000099.xml
|
|||
ART001474580
|
oai_dc
|
Dynamic behaviour of stiffened and damaged coupled shear walls
|
Dynamic behaviour of stiffened and damaged coupled shear walls
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"S. A. Meftah(Universitade Sidi Bel Abbes); A. Tounsi(Universitade Sidi Bel Abbes); E. A. Adda-Bedia(Universitade Sidi Bel Abbes)"
] |
The free vibration of stiffened and damaged coupled shear walls is investigated using the mixed finite element method. The anisotropic damage model is adopted to describe the damage extent of the reinforced concrete shear wall element. The internal energy of a locally damaged shear wall element is derived. Polynomial shape functions established by Kwan are used to present the component of displacements vector on each point within the wall element. The principle of virtual work is employed to deduce the stiffness matrix of a damaged shear wall element. The stiffened system is reinforced by an additional stiffening beam at some level of the structure. This induces additional axial forces, and thus reduces the bending moments in the walls and the lateral deflection, and increases the natural frequencies. The effects of the damage extent and the stiffening beam on the free vibration characteristics of the structure are studied. The optimal location of the stiffening beam for increasing as far as possible the first natural frequency of vibration is presented.
|
토목공학
| null |
kci_detailed_000099.xml
|
|||
ART001474581
|
oai_dc
|
Spatial dispersion of aggregate in concrete a computer simulation study
|
Spatial dispersion of aggregate in concrete a computer simulation study
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Jing Hu(Delft University of Technology); Huisu Chen(Delft University of Technology); Piet Stroeven(Delft University of Technology)"
] |
Experimental research revealed that the spatial dispersion of aggregate grains exerts pronounced influences on the mechanical and durability properties of concrete. Therefore, insight into this phenomenon is of paramount importance. Experimental approaches do not provide direct access to three-dimensional spacing information in concrete, however. Contrarily, simulation approaches are mostly deficient in generating packing systems of aggregate grains with sufficient density. This paper therefore employs a dynamic simulation system (with the acronym SPACE), allowing the generation of dense random packing of grains, representative for concrete aggregates. This paper studies by means of SPACE packing structures of aggregates with a Fuller type of size distribution, generally accepted as a suitable approximation for actual aggregate systems. Mean free spacing , mean nearest neighbour distance (NND) between grain centres , and the probability density function of D3 are used to characterize the spatial dispersion of aggregate grains in model concretes. Influences on these spacing parameters are studied of volume fraction and the size range of aggregate grains. The values of these descriptors are estimated by means of stereological tools, whereupon the calculation results are compared with measurements. The simulation results indicate that the size range of aggregate grains has a more pronounced influence on the spacing parameters than exerted by the volume fraction of aggregate. At relatively high volume density of aggregates, as met in the present cases, theoretical and experimental values are found quite similar. The mean free spacing is known to be independent of the actual dispersion characteristics (Underwood 1968); it is a structural parameter governed by material composition. Moreover, scatter of the mean free spacing among the serial sections of the model concrete in the simulation study is relatively small, demonstrating the sample size to be representative for composition homogeneity of aggregate grains. The distribution of observed in this study is markedly skew, indicating a concentration of relatively small values of . The estimate of the size of the representative volume element (RVE) for configuration homogeneity based on NND exceeds by one order of magnitude the estimate for structure-insensitive properties. This is in accordance with predictions of Brown (1965) for composition and configuration homogeneity (corresponding to structure-insensitive and structure-sensitive properties) of conglomerates.
|
토목공학
| null |
kci_detailed_000099.xml
|
|||
ART001474585
|
oai_dc
|
A mortar mix proportion design algorithm based \r\non artificial neural networks
|
A mortar mix proportion design algorithm based \r\non artificial neural networks
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Tao Ji(Fuzhou University); Xu Jian Lin(Fuzhou University)"
] |
The concepts of four parameters of nominal water-cement ratio, equivalent water-cement ratio, average paste thickness, fly ash-binder ratio were introduced. It was verified that the four parameters and the mix proportion of mortar can be transformed each other. The behaviors (strength, workability, et al.) of mortar primarily determined by the mix proportion of mortar now depend on the four parameters. The prediction models of strength and workability of mortar were built based on artificial neural networks (ANNs). The calculation models of average paste thickness and equivalent water-cement ratio of mortar can be obtained by the reversal deduction of the two prediction models, respectively. A mortar mix proportion design algorithm was proposed. The proposed mortar mix proportion design algorithm is expected to reduce the number of trial and error, save cost, laborers and time.
|
토목공학
| null |
kci_detailed_000099.xml
|
|||
ART001474584
|
oai_dc
|
Using radial basis function neural networks to model torsional strength of reinforced concrete beams
|
Using radial basis function neural networks to model torsional strength of reinforced concrete beams
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Chao-Wei Tang(Cheng-Shiu University)"
] |
The application of radial basis function neural networks (RBFN) to predict the ultimate torsional strength of reinforced concrete (RC) beams is explored in this study. A database on torsional failure of RC beams with rectangular section subjected to pure torsion was retrieved from past experiments in the literature; several RBFN models are sequentially built, trained and tested. Then the ultimate torsional strength of each beam is determined from the developed RBFN models. In addition, the predictions of the RBFN models are also compared with those obtained using the ACI 318 Code equations. The study shows that the RBFN models give reasonable predictions of the ultimate torsional strength of RC beams. Moreover, the results also show that the RBFN models provide better accuracy than the existing ACI 318 equations for torsion, both in terms of root-mean-square error and coefficients of determination.
|
토목공학
| null |
kci_detailed_000099.xml
|
|||
ART001474583
|
oai_dc
|
Design optimization of reinforced concrete structures
|
Design optimization of reinforced concrete structures
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Andres Guerra(Colorado School of Mines); Panos D. Kiousis(Colorado School of Mines)"
] |
A novel formulation aiming to achieve optimal design of reinforced concrete (RC) structures is presented here. Optimal sizing and reinforcing for beam and column members in multi-bay and multi-story RC structures incorporates optimal stiffness correlation among all structural members and results in cost savings over typical-practice design solutions. A Nonlinear Programming algorithm searches for a minimum cost solution that satisfies ACI 2005 code requirements for axial and flexural loads. Material and labor costs for forming and placing concrete and steel are incorporated as a function of member size using RS Means 2005 cost data. Successful implementation demonstrates the abilities and performance of MATLAB's (The Mathworks, Inc.) Sequential Quadratic Programming algorithm for the design optimization of RC structures. A number of examples are presented that demonstrate the ability of this formulation to achieve optimal designs.
|
토목공학
| null |
kci_detailed_000099.xml
|
|||
ART001474340
|
oai_dc
|
The fractal analysis of the fracture surface of concretes made from different coarse aggregates
|
The fractal analysis of the fracture surface of concretes made from different coarse aggregates
|
{
"journal_name": "국제구조공학회",
"publisher": null,
"pub_year": null,
"pub_month": null,
"volume": null,
"issue": null
}
|
[
"Grzegorz Prokopski(Rzeszow University of Technology); Janusz Konkol(Rzeszow University of Technology)"
] |
The article presents the results of examination of the fractal dimension D of concrete specimenfracture surfaces obtained in fracture toughness tests. The concretes were made from three different types of coarse aggregate: gravel, dolomite and basalt aggregate. Ordinary concretes (C40) and highperformance concretes (HPC) were subjected to testing after 7, 14, 28 and 90 days of curing, respectively. In fracture toughness and compressive tests, different behaviours of concretes were found, depending on the type of aggregate and class of concrete (C40, HPC). A significant increase in the strength parameters tested occurred also after a period of 28 days (up to the 90th day of curing) and was particularly large for concretes C40. Fractal examinations performed on fracture replicas showed that the fractal dimension D was diverse, depending on the coarse aggregate type and concrete class being, however, statistically constant after 7 and 14 days for respective concretes during curing. The fractal dimension D was the greater, the worse strength properties were possessed by the concrete. A cross-grain crack propagation occurred in that case, due to weak cohesion forces at the coarse aggregate/mortar interface. A similar effect was observed for C40 and HPC made from the same aggregate. A greater dimension D was exhibited by concretes C40, in which case the fracture was easier to form compared with highperformance concretes, where, as a result of high aggregate/mortar cohesion forces, the crack propagation was of inter-granular type, and the resulted fracture was flatter.
|
토목공학
| null |
kci_detailed_000099.xml
|
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