• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.897-902
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• 2001

Recently, structure performance is maximized by using high strength concrete. In design of structure, concrete need combination with reinforcement, but use of common strength reinforcement make member complex bar placement, so high strength concrete members require increased strength reinforcement. If common strength reinforcement replaced by equal tension area of high strength reinforcement, reinforcement ratio increase and brittle failure of member may occur by material change. So, adequate upper limit of strength ratio is required to affirm ductile behavior in application of high strength reinforcement. In this study, ductility behavior was analysed by factor of reinforcement ratio, strength of concrete and reinforcement. The result indicate that ductile failure is shown under 0.35 $\rho_{b}$ in any reinforcement strength of same section and high strength concrete of 800kg/$cm^{2}$ used commonly is compatible with reinforcement of 5500kg/$cm^{2}$.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.193-198
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• 1998

In this study, the change of concrete temperature, strain and thermal stress were measured by using the embedded type concrete gauges in tendon gallery wall of containment building. A finite element analysis was performed to clarify the thermal behavior of concrete. The analytic and test results were investigated to improve the validity of analytic method. According to the test results, concrete temperature, strain and thermal stress were strongly affected by measuring point and environment condition of member. And the thermal stress was developed in the member which was not demoulded at early ages. This is caused by the change of internal temperature and restrained condition. A finite element effectively interpreted the test results by estimating the concrete properties and the site condition.

• Computers and Concrete
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• v.22 no.2
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• pp.221-225
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• 2018

In this paper, vibration analysis of concrete foundations resting on soil medium is studied. The soil medium is simulated by Winkler model considering spring element. The concrete foundation is modeled by thick plate elements based on classical plate theory (CPT). Utilizing energy method consists of potential energy, kinetic energy and external works in conjunction with Hamilton's principle, the motion equations are derived. Assuming the simply supported boundary condition for the concrete foundation, the Navier method is used for calculating the frequency of the structure. The effect of different parameters such as soil medium, mode numbers, length to width ratio and length to thickness ratio of the concrete foundation are shown on the frequency of the structure. At the first, the results are validated with other published works in order to show the accuracy of the obtained results. The results show that considering the soil medium, the frequency of the structure increases significantly.

• Journal of Korean Society of Steel Construction
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• v.29 no.5
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• pp.353-359
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• 2017

The purpose of this study is to evaluate the strength and behavior of the composite member in case of concrete filled steel tube embedded in concrete for application concrete filled steel tube to steel rib support in tunnel. A total of six beam specimens were prepared for steel tube in-filled with plain concrete and aerated concrete, and static bending tests were performed. As a result, the member of concrete steel tube embedded with plain concrete showed higher strength than those with aerated concrete. However, it was found that the flexural strength of member with reinforcing bar around the steel tube is more influenced by the amount of the reinforcing bar than the type of the filled concrete.

• Magazine of the Korea Concrete Institute
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• v.6 no.5
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• pp.193-202
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• 1994

In this study, an equation for modelling the shear strength of reinforced concrete member with web reinforcement is proposed. Although the general formulas for shear strength of reinforced concrete member with small a /d are obtained based on the experimental results, the proposed equation herein is derived from lower bound theorem of limit analysis. The proposed model takes into account arch mechanism and truss mechanism. And ir provides the values of divided shear strength ratio of each mechanism as well as visual understanding of the mechanism on how the given load is transfered to the support. Also, the model takes into account the effect of a /d. longitudinal reinforcement ratio, and web reiriforcement ratio quantitively. Based on the comparisons of the result of this model with previous, test results, it shows good agreements.

• Computers and Concrete
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• v.17 no.5
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• pp.579-596
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• 2016

This paper describes a method of the refined plastic hinge approach in the framework of the higher-order element formulation that can efficaciously evaluate the limit state capacity of a whole reinforced concrete structural system using least number of element(s), whereas the traditional design of a reinforced concrete structure (i.e. AS3600; Eurocode 2) is member-based approach. Hence, in regard to the material nonlinearities, the efficient and economical cross-section analysis is provided to evaluate the element section capacity of non-uniform and arbitrary concrete section subjected to the interaction effects, which is helpful to formulate the refined plastic hinge method. In regard to the geometric nonlinearities, this paper relies on the higher-order element formulation with element load effect. Eventually, the load redistribution can be considered and make full use of the strength reserved owing to the redundancy of an indeterminate structure. And it is particularly true for the performance-based design of a structure under the extreme loads, while the uncertainty of the extreme load is great that the true behaviour of a whole structural system is important for the economical design approach, which is great superiority over the conservative optimal strength of an individual and isolated member based on traditional design (i.e. AS3600; Eurocode 2).

• Journal of Korean Society of Steel Construction
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• v.24 no.2
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• pp.137-147
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• 2012

This paper describes an experimental study on the mechanical characteristic and behavior of a structure that has a joint between the reinforced concrete (RC) member and steel plate concrete (SC) member. An out-of-plane flexural test on an L-type test specimen and in-plane shear test on an I-type test specimen were carried out by means of repeated cyclic loading until their failure. Based on the results, the former showed pull-out failure mode of anchored vertical bars while the latter exhibited flexural failure mode of the basement member. These results reveal that the maximum capacity of the specimens is 96% and 82%, respectively, compared with the theoretical value.

• Earthquakes and Structures
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• v.14 no.6
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• pp.525-535
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• 2018

This study presents a new beam-column model comprising material nonlinearity and joint flexibility to predict the nonlinear response of reinforced concrete structures. The nonlinear behavior of connections has an outstanding role on the nonlinear response of reinforced concrete structures. In presented research, the joint flexibility is considered applying a rotational spring at each end of the member. To derive the moment-rotation behavior of beam-column connections, the relative rotations produced by the relative slip of flexural reinforcement in the joint and the flexural cracking of the beam end are taken into consideration. Furthermore, the considered spread plasticity model, unlike the previous models that have been developed based on the linear moment distribution subjected to lateral loads includes both lateral and gravity load effects, simultaneously. To confirm the accuracy of the proposed methodology, a simply-supported test beam and three reinforced concrete frames are considered. Pushover and nonlinear dynamic analysis of three numerical examples are performed. In these examples the nonlinear behavior of connections and the material nonlinearity using the proposed methodology and also linear flexibility model with different number of elements for each member and fiber based distributed plasticity model with different number of integration points are simulated. Comparing the results of the proposed methodology with those of the aforementioned models describes that suggested model that only uses one element for each member can appropriately estimate the nonlinear behavior of reinforced concrete structures.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.3
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• pp.149-155
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• 2007

Damage assessment and Damage index for RC members failed in flexure was investigated by using the nonlinear finite element analysis, included with nonlocal constitutive law, which is analyzed for the localization of the failure on the post-peak region. In the nonlcal constitutive law, The local strains obtained at gauss points were averaged over a particular length, i.e. characteristic length and it was used to evaluate the damage of RC column member. As the analysis results, The value of nonlocal strain shows less mesh sensibility. In the damage assessment, It was confirmed that evaluations of damage of RC member were able to use nonlocal compressive strain on a cover concrete and a core concrete of the member. Moreover it was confirmed that damage process for the statically indeterminate structure was able to evaluate the damage context of the component members of the structure.

• Magazine of the Korea Concrete Institute
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• v.3 no.4
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• pp.117-123
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• 1991

It is widely recognized that the strengths of reinforced concrete members have random characteristics due to the variability of the mechanical properties of concrete and steel, the dimensional error as well as incorrect placement of reinforcing bars. Statistical models of the variabilities of strengths of reinforced concrete members, therefore, need to be developed to evaluate the safety level implied in current practices. Based on the probabilistic models of basic factors affecting the R.C. member strengths, in this study, the probabilistic characteristics of member resistance have been studied through Monte Carlo simulation.