• Architectural research
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• v.26 no.2
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• pp.31-39
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• 2024

The numerical study focuses on the analysis of the structural behavior of concrete beams containing outdated concrete and offers an innovative method of strengthening them using carbon-fiber-reinforced polymer sheets (CFRP). The focus is on modeling and analyzing the performance of aged concrete beams strengthened by CFRP in the flexural direction. This study presents an ultimate load model for CFRP-strengthened RC beams featuring outdated concrete layers. Validation through four-point bending tests and finite element modeling demonstrated the efficacy of the model. Findings indicate that CFRP sheets significantly enhance beam strength, particularly in structures with outdated concrete layers, resulting in increased ultimate load capacity. Moreover, an inverse relationship between ultimate load and concrete layer height was observed, with the CFS-21-15-30 sample exhibiting the most substantial reduction. Validation of the model was achieved using finite element analysis con-ducted in Abaqus software.

• Earthquakes and Structures
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• v.7 no.5
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• pp.627-645
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• 2014

Using OpenSees as a framework, constitutive models of reinforced, prestressed and prestressed steel fiber concrete found by the panel tests have been implemented into a finite element program called Simulation of Concrete Structures (SCS) to predict the seismic behavior of shear-critical reinforced and prestressed concrete structures. The developed finite element program was validated by tests on prestressed steel fiber concrete beams under monotonic loading, post tensioned precast concrete column under reversed cyclic loading, framed shear walls under reversed cyclic loading or shaking table excitations, and a seven-story wall building under shake table excitations. The comparison of analytical results with test outcomes indicates good agreement.

• Computers and Concrete
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• v.14 no.4
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• pp.405-417
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• 2014

The poor seismic performance of reinforced concrete buildings during the latest earthquakes has become a serious issue in the building industry in Turkey. This case, designing new buildings without structural irregularities against earthquake loads reveals to be quite significant. This study mainly is focused on the effects of different torsional irregularities on construction costs and earthquakes performance of reinforced concrete buildings. In that respect, structural torsional irregularities are investigated based on the Turkish Earthquake Code. The study consists of major eight main parametric models. In this models consist of totally 49 models together with the variations in the number of storey. With this purpose, the earthquake performances and construction costs (especially steel quantities) of reinforced concrete buildings which having different structural torsional irregularities were obtained with the help of Sta4-CAD program. Each model has been analyzed by both the methods of equivalent earthquake loading and dynamic analysis. The obtained results reveal that the model-1 which has lower torsional irregularity coefficient shows the best earthquake performance owing to its regular plan geometry. Also, economical comparisons on costs of the torsional irregularity are performed, and results-recommendations are given.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.203-210
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• 2002

In these days, High-strength steel prevails throughout the construction fields for the benefit of structural and economical aspects. But high-strength steel is used by the simple calculation of flexural capacities for the purpose of reducing flexural reinforcement. So, this paper is mainly focused on the shear behavior of high-strength steel reinforced concrete beams without stirrups comparing with normal-strength steel reinforced concrete beams. Specimens were made and tested with the experimental parameters, such as steel yield strength, reinforcement ratios and minimum shear reinforcement. The main result was that not only area but also the yield strength of flexural reinforcement should be considered to predict the shear capacities of concrete beams. In addition, the experimental results were simulated by modified compression field theory analysis program, RESPONSE 2000. A good agreement was achieved between the test results and program analyses.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.3
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• pp.99-108
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• 2012

In this paper, to intend anticorrosive effect and weight reduction of conventional reinforced concrete slab, lightweight concrete slab reinforced with glass fiber reinforced polymer(GFRP) bar was considered and some basic behaviour of the slab were investigated. Measurement of splitting tensile strength and fracture energy of the concrete, a number of flexural experiment of the slab, numerical analysis using nonlinear finite element analysis, and comparison of the experimental results to the numerical analysis, were conducted. As a result, even the weight of the lightweight concrete slab could be reduced by about 28% than the normal concrete slab, failure load of the lightweight concrete slab was 36% smaller than the normal concrete slab. Such a thing can be attributed to the lower axial stiffness and lower bond strength of GFRP bar. In the numerical analysis, to consider decreasing property of bond strength of the lightweight concrete, interface element was used between the concrete and the GFRP bar elements and this method was shown to be a better way for the numerical analysis to approach the experimental results.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.387-390
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• 2003

Direct tensile tests were carried out for the tensile members of steel-reinforced polymer concrete with different steel diameters and steel ratios to figure out the effect of tensile strength of polymer concrete. In the experiments, polymer concrete with $1000kgf/cm^2$ of compressive strength, steel with $5200kgf/cm^2$ of tensile strength, and the tensile members with 100 cm of constant length were used. Experimental results showed that, regardless of steel diameters and steel content, the strain energy exerted by concrete till the initial crack was 14-15% of the total energy till the point of yield: The energy was much larger than the one of high-strength cement concrete. The behaviors of tensile members of steel-reinforced polymer concrete were in relatively good agreement with the model suggested by Gupta-Maestrini (1990), which was idealized by the effective tensile stress-strain relationship of concrete and the load-strain relationship of members, while those showed a big difference from CEB-FIP model and ACI-224 equation suggested for the load-displacement relationship that was defined as the cross sectional stiffness of effective axis. Modified ACI-224 model code about the load-displacement relationship for the tensile members of steel-reinforced polymer concrete and theoretical equation for the polymer concrete tensile stiffness of polymer concrete suggested through the results of this study are expected to be used in an accurate structural analysis and design for the polymer concrete structural members.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.590-595
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• 2008

In the present paper, the impact damage behavior of steel plate reinforced concrete panels exposed to shock impulsive loading and fragment impact loading is investigated. To evaluate the retrofit performance of a steel-strengthened concrete panels, a numerical experiment using a numerical simulation with AUTODYN, an explicit analysis program is introduced because a real explosion experiment requires the vast investment and expense for facilities as well as the deformation mechanisms are too complicated to be reproduced with a conventional closed-form analyses. The model for the analysis is simplified and idealized as a two-dimensional and axisymmetric case controled with geometry, boundary condition and material properties in order to obtain a resonable computation time. As a result of the analysis, panels subject to either shock loading or fragment loading without the steel plate reinforcement experience the perforation with spalled fragments. In addition, the panels reinforced with steel plate can prevent the perforation and provide the good mechanical effect such as the increase of global stiffness and strength through the composite action between the concrete slab and the steel plate.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.729-732
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• 1999

In this paper, the Mohr-Coulomb criterion was adopted to predict the bonding failure load of the reinforced concrete beams strengthened by the externally bonded steel plates. Based on this criterion, a nonlinear analysis program of APSB(Analysis Program for Strengthened Beams) and nonlinear finite element analysis program of RCSD-SB (Reinforced Concrete Structural Design - Strengthened Beams) were developed. Numerical results were then compared with experimental results and good agreements were obtained.

• Structural Engineering and Mechanics
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• v.1 no.1
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• pp.75-86
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• 1993

The punching shear strength of concrete flat plates is one of the topics of intensive research in recent years by various concrete structures researchers. This paper reviews four current methods of analysing the punching shear strength at the corner-and edge-column positions of reinforced concrete flat plates. They include those recommended in the Australian Standard AS3600-1988, the American Concrete Institute ACI318-89 and the British Standard on Concrete Practices (BS8110) as well as the approach developed at the University of Wollongong, Australia. Based on half-scale model test results, a comparative study of these four analysis methods is made with regard to their limitation, accuracy and reliability. It is found that the Wollongong approach in general gives the best performance in predicting the punching shear strength of flat plates with torsion strips and those with spandrel beams. The Australian Standard procedure performs just as satisfactorily for flat plates with torsion strips but tends to be unsafe for those with spandrel beams. Both the ACI and the British methods are applicable only to flat plates with torsion strips; they also tend to give unsafe predictions for the punching shear strength.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1363-1372
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• 2014

In the previous study, the structural performance of proposed precast concrete arch with reinforced joint was evaluated by structural experiment. In this paper, finite element analysis considering both material and contact nonlinearity was carried out on the specimens of the previous study. Based on the result of analysis and experiment, friction coefficient between concrete blocks was determined. To evaluate the strength of sectional member, elastic analysis was carried out on the arch using linear elastic analysis program. The section force was compared with the nominal strength of arch section. It was concluded that the maximum load of all the specimens exceed the nominal strength of arch section. Those results of the strength evaluation were similar to the results of structural experiments. Therefore, it is concluded that the elastic analysis and ultimate strength model can effectively evaluate the strength for the proposed precast concrete arch composed of concrete blocks and reinforced joint in design.