• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.3
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• pp.361-371
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• 2000

RC structure is the composite material system combined concrete and steel showing different plastic behavior. Especially, concrete shows very complex plastic behavior. Therefore, for plastic analysis of RC structures, we have to model carefully each plastic behavior of concrete and steel member. But, because of divergency as well as difficulties and dimensions of modelling, it takes a lot of time and labor or sometimes it is impossible to perform plastic analysis of RC structures. In this study, for simplified plastic analysis of RC structures, we propose material transformation method by homogeneous and isotropic material which have the same plastic property as RC. We generate homogeneous and isotropic material showing the same moment-curvature curves (bi-linear stress-strain relation) as RC members, using bi-linear moment-curvature relation by yielding moment, yielding curvature and ultimate moment, ultimate curvature of RC member. Finally, we prove compatibility in the study by comparing plastic analysis results for various analysis models using transformed material models and RC model.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.568-573
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• 2010

본 논문에서는 압축하중 및 풍하중, 지진하중을 받는 RC (Reinforced Concrete) 빌딩 시공에 필요한 부재의 재료비를 최소화하기 위해 부재의 부피를 최소화하는 최적설계를 수행한다. 최적설계 수행을 위해 상용 PIDO (Process Integration and Design Optimization) 툴인 PIAnO (Process Integration, Automation and Optimization)에서 제공하는 다양한 설계기법들을 이용한다. 먼저 실험계획법을 사용하여 실험계획을 세우고, 실험점에 따라 범용 구조해석 프로그램인 MIDAS Gen을 사용하여 구조해석을 수행한다. 그리고 해석결과를 바탕으로 각 응답에 대한 근사모델을 생성한 후 근사모델과 최적화기법을 이용하여 최적설계를 수행하고, 제한조건을 만족하면서 부재의 부피를 최소화함으로써 제안된 설계방법의 유효성을 보인다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.16-25
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• 2018

Concrete is a suitable construction material for long-term structure, however, it is needed to understand the calcium leaching damage caused by exposure to underground pure water for a long time. In this paper, it is experimentally investigated that the characteristics of flexural behavior in RC member damaged by calcium leaching degradation. From the test results, when calcium leaching is happened, yielding load and flexural rigidity is reduced, neutral axis depth and displacement is increased. That is, calcium leaching degradation adversely affects RC member performance. And, when the mineral admixture is used in the calcium leaching environment, it is considered that the optimal replacement ratio should be prepared according to the type of mineral admixture.

• Journal of the Korean Geophysical Society
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• v.9 no.4
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• pp.301-310
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• 2006

In this short paper, an elasto-plastic repair and retrofit element is developed for the investigation of the seismic performance of damaged reinforced concrete members. The developed element is capable of reflecting the increased characteristics due to both repair and retrofitting for degraded strength and stiffness of the members. The element having both birth and death time can freely be activated within the user-defined time intervals during static and dynamic time-history analysis. Comparative studies are conducted for reinforced concrete members being repaired and retrofitted. Analytical predictions including the developed element display reasonable correlation with experimental results. In short, it is concluded that the developed element is capable of providing salient features for the healthy assessment of seismic performance of RC members being repaired and retrofitted.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.100-108
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• 2010

The axial strength of existing RC columns were experimentally investigated in this paper to understand the strength characteristics of existing structural members and to get a appropriate data in strengthening design of RC members in a remodelling construction. Ten RC columns were prepared by being cut and extracted directly from the demolition site of the apartment housings. Each column was tested under uniaxial loadings with different eccentricities in order to evaluate the axial strength of existing RC columns. From the test results, it was found that axial strength of all the specimens were at least 75% higher than those of the theoretical values required by current code. But member displacement ductility ratio were relatively low ranging from 2.12~5.86.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.75-82
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• 2010

The static strengths of the existing RC beams were experimentally investigated in this paper to understand the strength characteristics of existing structural members and to get appropriate data in strengthening RC members in the remodelling construction. Ten RC beams were prepared by cutting and extracting directly from the demolition site of apartment housings and tested in order to evaluate the flexural and shear strengths of existing RC beams by their geometric condition. From the test results, it was found that most of the specimens had a sufficient structural capacity except for some special case, for example, specimens with severe cracks or concrete losses caused by improper casting. Therefore, the severely deteriorated members originated from bad concrete casting or careless construction process should be repaired and strengthened in remodelling construction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.121-133
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• 1993

Presented is a study on the establishment of a method of advanced reliability analysis for the realistic analysis and design of reinforced concrete(RC) structures. Considerable variabilities exist in concrete structures due to random nature of concrete materials and member dimensions. The present study analyzes first the uncertainties in concrete, reinforcements and member dimensions and then a method is proposed to determine the probability uncertainties of basic variables. The limit state equations are also proposed for the RC members with axial compression and bending and RC footings. The advanced invariant second-moment method is applied to analyze those structures. The present study provides an important base for realistic reliability analysis of RC structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.177-184
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• 2021

In recent years, large-scale earthquake activity has occurred in Korea, and thus public interest in earthquakes is increasing. Accordingly, the importance of seismic performance management of structures is emerging. In particular, the collapse of a bridge, one of main road facilities, directly leads to many casualties. Therefore, engineers need to evaluate the seismic fragility of the bridge and prepare for the earthquake event. The service life of these bridges has been over 30 years, which requires a study on the aging effect on bridges. In this study, seismic analysis of the target RC slab bridge was performed considering the aging effects of each component of the bridge. Components of the bridge included pier and bearing, which dominate the seismic response of the bridge. The seismic performance of the bridge was evaluated using nonlinear static and dynamic analyses. In addition, the limit state and dynamic response of each component were used to evaluate the seismic fragility according to the aging of each component.

• Journal of Korean Association for Spatial Structures
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• v.6 no.3 s.21
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• pp.103-110
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• 2006

This study presents a technique to control quantitatively lateral drift of RC tall frameworks subject to lateral loads. To this end, lateral drift constraints are established by introducing approximation concept that preserves the generality of the mathematical programming and can efficiently solve large scale problems. Also the relationships of sectional properties are established to reduce the number of design variables and resizing technique of member is developed under the 'constant-shape' assumption. Specifically, the methodology of dynamic displacement sensitivity analysis is developed to formulate the approximated lateral displacement constraints. Three types of 10 and 50 story RC framework models are considered to illustrate the features of dynamic stiffness-based optimal design technique proposed in this study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.93-99
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• 2015

This paper is on a practical method for determination of the economical steel ratio in RC flexural members with an equal safety factor. The cost functions of each material and labor are considered to construct the cost function. Then, an equation for determination of the economical flexure steel ratio with the lowest construction cost were proposed. It was found that a relevant steel ratio is recommended to be 0.65~1.0% for designing singly reinforced rectangular beam.