• Computers and Concrete
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• 제27권5호
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• pp.457-472
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• 2021

Reinforced concrete (RC) buildings in Taiwan have suffered failure from strong earthquakes, which was magnified by the non-ductile detailing frames. Inadequate reinforcement as a consequence of the design philosophy prior to the introduction of current standards resulted in severe damage in the column and beam-column joint (BCJ). This study establishes a finite element analysis (FEA) of the non-ductile detailing RC column, BCJ, and three-story building that was previously tested through a tri-axial shaking table test. The results were then validated to laboratory specimens having the exact same dimensions and properties. FEA simulation integrates the concrete damage plasticity model and the elastic-perfectly plastic model for steel. The load-displacement responses of the column and BCJ specimens obtained from FEA were in a reasonable agreement with the experimental curves. The resulting initial stiffness and maximum base shear were found to be a close approximation to the experimental results. Also, the findings of a dynamic analysis of the three-story building showed that the time-history data of acceleration and displacement correlated well with the shaking table test results. This indicates the FEA implementation can be effectively used to predict the RC frame performance and failure mode under seismic loads.

• Geomechanics and Engineering
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• 제32권1호
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• pp.69-84
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• 2023

This paper proposes a novel frame element on Winkler-Pasternak foundation for analysis of a non-ductile reinforced concrete (RC) member resting on foundation. These structural members represent flexural-shear critical members, which are commonly found in existing buildings designed and constructed with the old seismic design standards (inadequately detailed transverse reinforcement). As a result, these structures always experience shear failure or flexure-shear failure under seismic loading. To predict the characteristics of these non-ductile structures, efficient numerical models are required. Therefore, the novel frame element on Winkler-Pasternak foundation with inclusion of the shear-flexure interaction effect is developed in this study. The proposed model is derived within the framework of a displacement-based formulation and fiber section model under Timoshenko beam theory. Uniaxial nonlinear material constitutive models are employed to represent the characteristics of non-ductile RC frame and the underlying foundation. The shear-flexure interaction effect is expressed within the shear constitutive model based on the UCSD shear-strength model as demonstrated in this paper. From several features of the presented model, the proposed model is simple but able to capture several salient characteristics of the non-ductile RC frame resting on foundation, such as failure behavior, soil-structure interaction, and shear-flexure interaction. This confirms through two numerical simulations.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1991년도 가을 학술발표회 논문집
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• pp.81-89
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• 1991

Recently increasing number of highrise buildings are aseismically designed by dynamic analysis method. To perform comparative study on the results of seismic design by dynamic analysis method, five-to thirty-story building models of ductile moment resisting frames and braced frames are considered. Base shears of these models using the spectrum of equivalent static method in the current Korean code and the ones of dynamic analysis method in the UBC-88 code are compared. Based on this study design spectra to be used in the dynamic analysis in Korea are proposed and the results are compared.

• 한국구조물진단유지관리공학회 논문집
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• 제25권3호
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• pp.48-56
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• 2021

최근 세계적으로 발생한 지진으로 구조물의 내진보강에 대한 관심이 높아지고 있다. 구조물의 내진성능 향상을 위하여 기둥에 대한 내진 보강이 이루어져야 한다. 기둥의 내진성능을 개선하기 위하여 다양한 보강법이 개발되고 있다. 본 연구에서는 RC기둥의 내진성능을 향상시키기 위하여, 기둥의 표면에 구속응력을 가력하여 내진성능을 평가하기 위한 해석적 연구를 수행하였다. 해석적 연구를 위하여 기둥에 대한 실험연구를 활용하였으며, 실험결과와 해석결과의 파괴형상 및 거동특성을 비교하였다. 해석결과 표면구속응력의 강도에 따라 RC기둥의 연성거동이 발생하였다. 일정 표면구속강도 이상에서는 연성거동이 거의 일정하게 발생하였다. 실험결과와 비교하여 실험에서 사용된 보강재의 보강정도를 RC기둥에 대한 표면구속응력값과 비교하여, 보강효과를 표면구속응력으로 검토하였다. 결론적으로, 본 연구에서 RC기둥의 연성거동을 위한 표면구속응력과 구속강도를 도출하였다. 도출한 결과를 바탕으로 RC기둥의 연성거동유도를 이용한 내진 설계 방법 및 내진성능 보가효과의 검토에 대한 기초자료로 활용이 가능할 것으로 판단된다.

• 콘크리트학회논문집
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• 제19권1호
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• pp.19-26
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• 2007

최근까지 우리나라는 활성단층으로부터 멀리 떨어져 있기 때문에 지진에 대하여 안전지대라 여기었다. 그러나 최근의 강진으로 인간의 생명과 국가 경제에 막대한 손실을 발생시킨다는 것을 인지하게되었다. 따라서 최근에는 사회기간시설물에 대한 내지설계의 중요성이 부각되고 있다. 본 연구에서는 82개 원형단면과 54개의 사각단면의 철근콘크리트 교각에 대한 국내외의 실험 결과를 이용하여 철근콘크리트 교각의 내진설계와 성능평가에 대한 새로운 방법을 제안하였다. 제안된 새로운 내진설계법은 중저진지역에 속하는 우리나라의 실정에 맞도록 한정연성설계 개념을 도입하였다. 또한 우리나라의 철근콘크리트 교각의 내진성능에 있어 중요한 점은 1992년 내지설계규정이 도입되기 이전에 시공된 교각들의 내진성능 확보이다. 따라서 제안된 철근콘크리트 교각의 내진성능평가식은 기존 교각들의 내진 보수 및 보강 방안을 선정하는데 유익하게 사용될 수 있으리라 판단된다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.249-252
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• 2008

Micro V-notching process has been used to manufacturing the safety component in Li-Ion battery. These kinds of safety component in Li-Ion battery plays an important role in the explosion from excessive overheating. Therefore, it is very crucial to estimate accurately the working pressure range of the safety component with micro V-notch. In this study, the relationship with the working internal pressure in Li-Ion battery and fracture phenomenon in micro V-notch was investigated through the numerical analysis. The numerical analysis is especially adopted the finite element method with ductile fracture criteria.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.291-295
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• 2003

The occurrence of ductile fracture is the working limit of many metal forming processes. It is necessary to predict the criteria and to apply the condition in a process design. Over the years. the way for clarifying conditions have been studied and presented. However such a way needs lots of experiments and analysis. In this study, in order to determine the critical damage value of a used material Cu 4N, it was performed a tensile test and FEM analysis by using DEFORM 2D. For applying the obtained critical damage value it was also performed a upsetting test by using DEFORM 2D. The way of determining a critical damage value which is presented in this study will make possible to find easily it which is one of the working limit factor. And the way of determining a critical damage value will make possible to find in multi-pass drawing process.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.733-736
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• 1999

R/C columns, one of the main structural members of reinforced concrete structures, usually sustain the axial forces of combined dead loads and live loads. When subjected to lateral loads, however, they are repeatedly subjected to bending moment, shearing forces and brittle failure such as shear failure can occur. This failure mode is not desirable and extra reinforcement is usually needed to induce a ductile failure. The design equation which is used to evaluate the maximum shear strength of a R/C column is still unsatisfactory. The objective of this study was, therefore, to evaluate the hysteretic strengthening effect and the maximum shear strength of R/C columns strengthened using carbon fibers on the seismic performance of the R/C columns under anti-symmetrical by acting moment. According to this study, it may be suggested that the shear of the strengthened R/C column were adequate to induce ductile failures.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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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/$cm^{2}$.

• 한국정밀공학회지
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• 제17권10호
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• pp.170-179
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• 2000

The objective of this study is to develop an analytical module for the prediction of burr formation during cutting process using the finite element method. This module is based on the rigid-plastic finite element method, ductile fracture criterion, fracture propagation technique and node separation criterion. The sequence of burr formation from burr initiation through end of burr formation is simulated and investigated by this module. The effect of material properties, such as AL6061-T6, AL2024-T4 and Copper, and cutting condition, such as rake angle and cutting depth, on burr formation is also discussed in this study. To validate this module the analysis results are compared with experimental ones.