• Journal of the Earthquake Engineering Society of Korea
• /
• v.1 no.1
• /
• pp.1-10
• /
• 1997

Current seismic design philosophy for reinforced concrete (RC) structures on energy dissipation through large inelastic defomations. A nonlinear dynamic analysis which is used to represent this behavior is time consuming and expensive, particularly if the computations have to be repeated many times. Therefore, the selection of an efficient yet accurate alogorithm becomes important. The main objective of the present study is to propose a new technique herein called the prediction approach with siffness measure (PASM) method in the convetional direct integration methods, the triangular decomposition of matrix is required for solving equations of motion in every time step or every iteration. The PASM method uses a limited number of predetermined decomposed effective matrices obtained from stiffness states of the structure when it is deformed into the nonlinear range by statically applied cyclic loading. The method to be developed herein will reduce the overall numerical effort when compared to approaches which recompute the stiffness in each time step or iteration.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.3 no.3
• /
• pp.55-62
• /
• 1999

For the efficient performance of steel and composite building structures subjected to strong earthquake, one of current research investigates the cyclic behavior of open-web composite beams. Both experimental test and nonlinear FEM analysis demonstrate their behavior so ductile that four T-sections around the corners of rectangular web-opening develop plastic hinges prior to potential brittle failure at the beam end, i.e. at the column face. This research proposes simplified equations for determining strength and initial stiffness of composite beams with a rectangular web-opening, and compares its results with those of experimental test and nonlinear FEM analysis.

• Journal of Korean Society of Steel Construction
• /
• v.9 no.4 s.33
• /
• pp.637-647
• /
• 1997

As stated in Part(I), the use of the isolator is meant to protect a structure from seismic risk, by concentrating the inelastic deformations to relatively cheap and replaceable devices while the rest of the structures remains elastic. This research has been carried out to investigate the effects of various structural parameters and isolator characteristics on the seismic response of Base Isolated Bridges. Simplified analysis method for practical design is developed by using the results. The Proposed Code-Type approach method can be used to estimate the inertial forces accurately, not only at the isolator but throughout the height of the Base-Isolated Bridges. The proposed method is recommended to use in preliminary design tool or even a final design tool for Base Isolated Bridges. For the validation of simplified design method, examples with artificial earthquake time history and design response spectrum for P.C Box Bridge with bilinear hysteretic steel damper are evaluated.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.12 no.3
• /
• pp.293-308
• /
• 1999

이 논문에서는 패널, 깊은 보 그리고 전단벽과 같이 평면응력상태하에 있는 철근콘크리트 구조물의 비선형 유한요소해석에 있어서의 직교이방성 콘크리트 구성 모델의 적용성을 보여준다. 등가의 일축 변형을 개념을 토대로 콘크리트의 구성 관계가 주변형률 축과 일치하고 하중이력에 따라 회전하는 직교하는 축에 대해 제시된다. 제안된 모델은 이축 압축응력상태와 인장-압축 응력상태에서 각각 압축강도의 증가와 인장 저항력의 감소효과를 보여주는 이축 파괴영역의 정의를 포함한다. 인장균열이 발생한 후, 콘크리트의 압축강도의 감소효과가 제시되고, 인장강화효과로 알려진 철근에 의해 지지되는 콘크리트의 인장응력이 고려된다. 평균응력과 평균변형률 개념을 사용하여 힘의 평형, 적합조건 그리고 철근과 철근을 둘러싼 콘크리트 사이의 부착응력-슬림 관계를 토대로 인장강화효과를 모사하기 위한 모델이 제안된다. 유한요소 모델에 의한 예측은 유용한 실험자료와의 비교에 의해 입증된다. 이 논문에서는 해석결과와 이상화한 전단 패널실험으로부터 얻어진 실험값의 비교연구가 수행되고, 제안된 모델의 타당성을 보여주기 위해 서로 다른 응력상태하의 전단 패널 보와 벽체의 힘-변위 관계를 평가하였다.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.14 no.2
• /
• pp.225-235
• /
• 2001

본 연구는 물리·역학적 특성을 고려한 점탄성 감쇠기의 수치모델에 의한 강뼈대구조물의 지진응답개선에 관해서 조사하고자 한다. 온도변화에 의한 감쇠기 이력거동에 미치는 영향을 고려하기 위하여, 점탄성 감쇠기의 모델은 온도-주기 등가원리와 더불어 개선된 분수도함수법에 기초하여 정식화하였다. 본 감쇠기 모델의 알고리즘을 일반화된 강뼈대구조물의 비선형 동적 해석 프로그램에 추가하였다. 강뼈대구조물에 대한 해석 예를 통하여, 제시된 모델에 의한 점탄성 감쇠기의 지진응답개선에 관한 효과를 확인할 수 있었다.

• Journal of the Korean Geotechnical Society
• /
• v.39 no.12
• /
• pp.7-22
• /
• 2023

In this study, the limit range of input acceleration was investigated based on time domain and response spectrum analyses by considering the relative density, groundwater depth, and soil type. Special attention was paid to the input acceleration and shear modulus of soil, which affect pile behavior. The surrounding soil was identified as an elastoplastic material and subjected to FLAC3D analysis using the Mohr-Coulomb and Finn models as well as FB-Multiplier analysis using a nonlinear p-y curve for soil spring. Based on the analyses, the limit range of acceleration on the pile is much higher for SP soil than for SM soil, and the groundwater level tends to reduce the limit range of input acceleration, irrespective of soil conditions. The limit range of acceleration was mainly affected by the shear modulus. The limit range of acceleration with nonlinear soil behavior is proportional to the relative density of the surrounding soil.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.16 no.2
• /
• pp.1-13
• /
• 2012

Seismic fragility functions are derived for probabilistic evaluation of seismic control performance of energy dissipation devices installed in reinforced concrete structures. Displacement-dependent dampers are added to the nonlinear single-degree-of-freedom systems with different natural periods and hysteretic characteristics of which stiffness and strength has uncertainty. Nonlinear time history analysis is conducted for those SDOF systems and the result is processed statistically to obtain seismic fragility functions in the form of log normal distribution. Variation of seismic fragility functions for different parameters of SDOF systems and dampers are investigated and the seismic control performance is assessed probabilistically.

• Journal of Korean Society of Steel Construction
• /
• v.15 no.4 s.65
• /
• pp.379-388
• /
• 2003

The response of single story buildings and other case studies were investigated to observe trends and develop a better understanding of the impact of some design parameters on the seismic response of Concentrically Braced Frames (CBF). While many parameters are known to influence the behavior of braced frames, the focus of this study was mostly on quantifying energy dissipation in compression and its effectiveness on seismic performance. Based on dynamic analyses of single story braced frame and case studies, a bracing member designed with bigger R and larger KL/r was found to result in lower normalized cumulative energy ratio in both cases.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.15 no.4
• /
• pp.45-54
• /
• 2011

A simple model for reinforced concrete shear walls with boundary elements is proposed, which is a macro-model composed of spring elements representing flexure and shear behaviors. The flexural behaviour is represented by vertical springs at the wall ends, where the moment strength and rotational capacity of the wall are based on section analysis. The shear behaviour is represented by a horizontal spring at the wall center, where the key parameters for the shear behavior are based on the flexural behaviour since the shear walls with boundary elements are governed by the flexure. The proposed model was prepared with the results of hysteretic tests of the shear walls, and then the reliability of the hysteretic rule and variables was investigated by nonlinear dynamic analyses. Using parametric study with nonlinear dynamic analyses, the effect of the variables on demand and capacity, which are major parameters in seismic performance evaluation, are investigated. Results show that the measured and calculated shear forces versus the shear distortion relationships are slightly different, but the global response is well simulated. Furthermore, the demand and capacity are also changed in a similar way to the change in the major parameters so that the proposed model may be appropriate for reinforced concrete shear walls with boundary elements.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.13 no.3
• /
• pp.373-384
• /
• 2000

To assess the safety of nonlinear steel frame structures subjected to short duration dynamic loadings, especially seismic loading, a nonlinear time domain reliability analysis procedure is proposed in the context of the stochastic finite element concept. In the proposed algorithm, the finite element formulation is combined with concepts of the response surface method, the first order reliability method, and the iterative linear interpolation scheme. This leads to the stochastic finite element concept. Actual earthquake loading time-histories are used to excite structures, enabling a realistic representation of the loading conditions. The assumed stress-based finite element formulation is used to increase its efficiency. The algorithm also has the potential to evaluate the risk associated with any linear or nonlinear structure that can be represented by a finite element algorithm subjected to seismic loading or any short duration dynamic loading. The algorithm is explained with help of an example and verified using the Monte Carlo simulation technique.