• Journal of Navigation and Port Research
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• v.33 no.3
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• pp.235-240
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• 2009

Simulation method based on probability was developed to evaluate the durability of reinforced concrete structures about chloride attack. The effects of the probability parameters(surface chloride ion concentration, initial combined chloride ion concentration, the depth of cover thickness of concrete, and the chloride ion diffusion coefficient), probability distribution function and it's variation were calculated using the Monte Carlo method and Fick's 2nd law. From the durability design method proposed in this study, the following results were obtained. 1) The effects of the distance from the coast and the chloride ion diffusion coefficient to the corrosion probability were quite high. 2) The effect of the variation of each parameters was relatively low.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.439-452
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• 1994

A method to optimize the cost of R/C frames and an algorithm of the optimal limit state design for R/C frames subjected to dynamic loads are presented. The modal superposition method was used to find the dynamic responses of the frames. Each member of R/C frame is made up of more than two elements and the stiffness matrix and consistent mass matrix of three d.o.f in the node of each element was used to include axial, shear and flexural effects. The objective function to be minimized formulated the cost of materials, steel and concrete, and optimised to satisfy the behaviors of R/C frame and each constraint imposed by the limit state requirements. Both objective function and each constraint are derived in terms of design variables which include the effective depth, beam width, compression and tension steel area, and column shear steel area. A few applications are presented which demonstrate the feasibility, the validity and efficiency of the algorithm for automated optimum design of R/C frames where dynamic behavior is to be considered.

• Magazine of the Korea Concrete Institute
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• v.9 no.6
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• pp.233-241
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• 1997

최근 해안환경하에 있는 콘크리트구조물의 철근부식은 구조물의 내구성 저하 및 유지관리라는 차원에서 커다란 문제점을 가지고 있다. 이와 같은 현상은 해양구조물의 건설이 날로 증가하고 있고, 또 콘크리트 제조시 잔골재의 일부를 염분이 함유된 해사를 사용함으로써 더욱 심각해지고 있다. 본 연구에서는 콘크리트 표면으로부터 침투해 들어오는 침입염분의 거동을 모델화하였으며, 콘크리트 세공속의 수용액상에 있은 염화물이온의 확산을 포함하는 물리 화학적 진행, 시멘트 수화물에 고정되는 염분의 흡착과 탈착 및 고정염과의 화학반응 등의 현상을 유한요소법에 의해 해석을 실시하였다. 본 연구의 결과는 콘크리트 내부의 철근 발청시기의 예측, 해안환경하에 있는 콘크리트 구조물의 침투 염분에 의한 콘크리트 덮개의 결정, 콘크리트 구조물의 염화물이온의 허용치 설정을 비롯하여 내구년수를 예측하는데 유용하게 활용될 수 있을 것으로 기대된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.323-329
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• 2011

Most current design codes of concrete structures adopt the partial safety factor format to assure the proper safety margin or reliability against various limit states as a practical design tool. The safety factors, load and resistance factors and so on, are determined based on the theory of structural reliability, which takes into account the statistical uncertainties of both loads and resistances. The establishment of statistical models for load and resistance should be preceded the application of reliability theory. In this paper, especially the influence of the statistical variations of resistance models, which are described in terms of strength of concrete, strength of reinforcements and sectional dimensions and so on, are examined and the probabilistic models for resistance of reinforced concrete members were developed. The statistical data were collected on local tests and experiments in Korea and the Monte Carlo simulation (MCS) technique was used. The results of this paper may be useful and valuable in calibration of design code in this country.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.109-116
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• 2010

Three-dimensional finite element model for analysis of reinforced concrete members was developed in order to investigate the prediction of bending and shear failure of reinforced concrete beams. A failure surface of concrete in strain space was newly proposed in order to predict accurately the ductile response of concrete under multi-axial confining stresses. Cracking of concrete in triaxial state was incorporated with considering the tensile strain-softening behavior of cracked concrete as well as the cracked shear behavior on cracked surface of concrete caused by aggregate interlocking and, dowel action. By correlation study on failure types of bending and shear of beams, current finite element model was well simulated not only the type of ductile bending failure of under-reinforced beams but also the type of brittle shear failure of no-stirruped reinforced concrete beam.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.297-300
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• 2008

This study focuses on the evaluation of efficiency of the explicit FEM program LS-DYNA to predict the failure behavior of reinforced concrete. Analysis variables of reinforced concrete beams were longitudinal bar ratio, shear steel ratio and span-depth ratio. Failure behavior of reinforced concrete beams was approximately simulated by LS-DYNA.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.4 s.50
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• pp.35-44
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• 2006

The purpose of this study is to investigate the inelastic behavior of hollow reinforced concrete bridge columns under varying axial load. The role of the variable axial load is very important in the ductility, strength, stiffness, and energy dissipation. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The proposed numerical method for the inelastic behavior of hollow reinforced concrete bridge columns under varying axial load is verified by comparison with reliable experimental results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.331-340
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• 2008

This study is to suggest the details of new concept of bridge deck. Experimental studies on the behavior of a inverted T-shaped steelconcrete composite deck were carried out. The part of inverted T-shaped steel is embedded in concrete. Reinforced concrete deck specimen and composite deck specimens were fabricated and static bending fracture tests were conducted. The ultimate strength and fracture strength of specimens were evaluated. The effects of shear hole crossing bars of composite deck were also analyzed. From the results of experiments, composite deck with shear hole crossing bar increased shear strength, and showed typical tensile failure. Ultimate strength and fracture strength of composite deck with shear hole crossing bar are higher than those of reinforced concrete deck. The displacement of composite deck is higher than that of reinforced concrete deck.

• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.143-150
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• 2014

To avoid abrupt torsional failure due to concrete crushing before yielding of torsional reinforcement and control the diagonal crack width, design codes specify the limitations on the yield strength of torsional reinforcement of RC members. In 2012, Korean Concrete Institute design code increased the allowable maximum yield strength of torsional reinforcement from 400 MPa to 500 MPa based on the analytical and experimental research results. Although there are many studies regarding the shear behavior of RC members with high strength stirrups, limited studies of the RC members regarding the yield strength of torsional reinforcement are available. In this study, twelve RC beams having different yield strength of torsional reinforcement and compressive strength of concrete were tested. The experimental test results indicated that the torsional failure modes of RC beams were influenced by the yield strength of torsional reinforcement and the compressive strength of concrete. The test beams with normal strength torsional reinforcement showed torsional tension failure, while the test beams with high strength torsional reinforcement greater than 480 MPa showed torsional compression failure. Therefore, additional analytical and experimental works on the RC members subjected to torsion, especially the beams with high strength torsional reinforcement, are needed to find an allowable maximum yield strength of torsional reinforcement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.396-402
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• 2021

A cross section in RC flexural members must be designed to satisfy flexural strength and ductility requirements simultaneously. In design provisions, ductile behavior is ensured by a sufficient reinforcement ratio or depth of the neutral axis. If the reinforcement ratio is less than the balanced reinforcement ratio, ductile behavior is secured, and this value is theoretically the maximum reinforcement ratio. But for a cross section with less steel, brittle failure can occur regardless of ductile behavior because of unqualifying a cracking moment. Recently, designs with a minimum steel ratio have been increasing along with the use of high-strength material, so in design provisions, a minimum amount of reinforcement is suggested. In the KCI(2012) standard, a minimum amount of reinforcement was suggested in terms of strength of steel and concrete. But in the revised KCI(2017) standard, a minimum amount of reinforcement was suggested by a relationship between the design flexural strength and cracking moment indirectly. This code can reflect the effect of cover thickness, but a material model must be defined. Therefore, the minimum amount of reinforcement in KCI(2012) and KCI(2017) was examined, and a rational review method was studied by parametric analysis.