• Title, Summary, Keyword: inelastic seismic behavior

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Performance-based design of tall buildings for wind load and application of response modification factor

  • Alinejad, Hamidreza;Jeong, Seung Yong;Kang, Thomas H.K.
    • Wind and Structures
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    • v.31 no.2
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    • pp.153-164
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    • 2020
  • In the design of buildings, lateral loading is one of the most important factors considered by structural designers. The concept of performance-based design (PBD) is well developed for seismic load. Whereas, wind design is mainly based on elastic analysis for both serviceability and strength. For tall buildings subject to extreme wind load, inelastic behavior and application of the concept of PBD bear consideration. For seismic design, current practice primarily presumes inelastic behavior of the structure and that energy is dissipated by plastic deformation. However, due to analysis complexity and computational cost, calculations used to predict inelastic behavior are often performed using elastic analysis and a response modification factor (R). Inelastic analysis is optionally performed to check the accuracy of the design. In this paper, a framework for application of an R factor for wind design is proposed. Theoretical background on the application and implementation is provided. Moreover, seismic and wind fatigue issues are explained for the purpose of quantifying the modification factor R for wind design.

Seismic Performance Evaluation of Building Structures Based on the Adaptive Lateral Load Distribution (적응적 횡하중 분배방법을 이용한 건축구조물의 내진성능평가)

  • 이동근;최원호;정명채
    • Journal of the Earthquake Engineering Society of Korea
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    • v.8 no.1
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    • pp.39-58
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    • 2004
  • It is very important that predict the inelastic seismic behavior exactly for seismic performance evaluation of a building in the performance based seismic design. Evaluation method of seismic performance based on the pushover analysis reflected in PBSE was developed by some researchers. For the evaluation of inelastic global and local seismic responses by pushover analysis exactly. lateral load distribution should be adjusted and reflected the dynamic characteristics of structural system and various seismic ground motions. And performance point should be determined based on the evaluation of reasonable deformation capacity of a building more exactly. An effective method based on the improved the adaptive lateral load distribution and the equivalent responses of a multistory building is proposed in this study to efficiently estimate the accurate inelastic seismic responses. The proposed method can be used to evaluate the seismic performance for the global inelastic behavior of a building and to accurately estimate its local inelastic seismic responses. In order to demonstrate the accuracy and validity of this method, inelastic seismic responses estimated by the proposed method are compared with those obtained from other analytical methods.

Effect of Hysteretic Characteristics on Inelastic Seismic Design Spectra (비탄성 설계스펙트럼에 대한 이력거동 특성의 영향)

  • 오영훈;한상환;이리형
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.207-214
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    • 1997
  • Current seismic design code is based on the assumption that the designed structures would be behaved inelastically during a severe earthquake ground motion. For this reason, seismic design forces calculated by seismic codes are much lower than the forces generated by design earthquakes which makes structures responding elastically. Present procedures for calculating seismic design forces are based on the use of elastic spectra reduced by a strength reduction factors known as "response modificaion factor". The effect of hysteretic behavior, as well as maximum ductility ratio and period on the inelastic strength demand is investigated. Special emphasis is given to the effects of the hysteretic characteristics such as strength degradation or pinching. Results indicate that inelastic strength demands are strongly dependent on level of inelastic deformation, period and hysteretic behavior.

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Inelastic Time History Analysis of a 5-Story Reinforced Concrete IMRF (5층 철근콘크리트 중간모멘트골조의 비탄성 시간이력해석)

  • Kang, Suk Bong;Lim, Byeong Jin
    • Journal of the Earthquake Engineering Society of Korea
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    • v.16 no.6
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    • pp.13-20
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    • 2012
  • In this study, 5-story structures were designed in accordance with KBC2009 for inelastic time history analysis of RC IMRF. Bending moment-curvature relationship for beam and column was identified with fiber model and bending moment-rotation relationship for beam-column joint was calculated with simple and unified joint shear behavior model and moment equilibrium relationship for the joint. The hysteretic behavior was simulated with three-parameter model suggested in IDARC program. The analytical results showed that the inelastic shear behavior of the joint could be neglected in the structural design for seismic design category C but the structure of category D did not satisfy the criteria of FEMA 356 for collapse prevention performance level.

Seismic Fragility Analysis of Torsionally Irregular Wall Structures (평면 비대칭 벽식 구조물의 지진 취약도 분석)

  • Ha, Tae-Hyu;Hong, Sung-Gul
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.161-168
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    • 2005
  • Torsional behavior of eccentric structure under seismic loading may cause the stress and/or deformation concentration. Hence it is hard to estimate the seismic behavior of the structure with plan irregularity. This study suggests the method to setup the seismic fragility curve of the torsionally irregular structures. The suggested fragility curve may be acquired from the fragility surface defined on the D-R plan according to the estimated torsional behavior. The torsional behavior is predicted considering the inelastic region by adapting the inelastic stiffness of each wall. Finally the system displacement is converted to the spectral acceleration and the fragility curve for the seismic excitation level is presented. In addition, the fragility curve considering the excitation direction is proposed.

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Inelastic Energy Absorption Factor for the Seismic Probabilistic Risk Assessment of NPP Containment Structure (확률론적 지진위험도 분석을 위한 원전 격납건물의 비탄성에너지 흡수계수 평가)

  • 최인길;서정문
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.5
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    • pp.47-56
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    • 2001
  • In order to assure the safety of NPP structures, margin of safety or conservatism is incorporated in each design step. Seismic risk evaluation of NPP structures is performed based on the realistic capacity and response of structure eliminated the safety margin and conservatism. In this study, the comparative study on the various evaluation methods of the inelastic energy absorption capacity was performed. The inelastic energy absorption capacity due to the nonlinear behavior of structures has significant effect on the results of seismic probabilistic risk assessment. And the comparison study of the HCLPF(high confidence of low probability of failure) values according to the inelastic energy absorption factors was performed. As a conclusion, the inelastic energy absorption factor of NPP containment structure is estimated about 1.5~1.75. It is essential to estimate the nonlinear behavior of structure and its ductility factor correctly for the seismic risk assessment.

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A Study of influence factors on the bridge seismic behavior (교량의 지진거동에 미치는 영향인자에 관한 연구)

  • Choi, Jong-Man;Kook, Seung-Kyu;Kim, Jun-Bum;Jung, Dong-Won
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.372-379
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    • 2005
  • The earthquake resistant design concept allows the nonlinear behavior of structures under the design earthquake. Therefore the response spectrum method provided in most codes introduces the response modification factors to consider the nonlinear behavior in the design process. For bridges, the response modification factors are given according to the ductility as well as the redundancy of piers. In this study, among influence factors on the nonlinear seismic behavior, the randomness of artificial accelerograms simulated with different durations, the pier ductility represented by the inelastic behavior characteristic curve and the regularity represented by pier heights are selected. The influence of such factor on the seismic behavior is investigated by comparing response modification factors calculated with the nonlinear time step analysis.

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Comparative Study on Evaluation of Inelastic Energy Absorption Capacity for Seismic Fragility Analysis of Structures (구조물의 지진취약도분석을 위한 비탄성에너지흡수능력의 평가 기법에 관한 비교 연구)

  • 조양희;조성국;박형기
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.135-142
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    • 2002
  • This paper introduces the technologies related to seismic resistance assessment of nuclear power plant structures by seismic fragility analysis(SFA). The inelastic energy absorption factor is considered in SFA to represent the effects due to the nonlinear behavior of structures and has a significant effect on the seismic fragility that is a probability of failure of structures by earthquake. Several practical methods to evaluate the inelastic energy absorption capacity of structures are investigated. The capacities determined by those methods are compared with each other. And an improved method that uses the inelastic demand capacity diagram is presented. Conclusively, some comments on each method for practical application are made.

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Transverse seismic response of continuous steel-concrete composite bridges exhibiting dual load path

  • Tubaldi, E.;Barbato, M.;Dall'Asta, A.
    • Earthquakes and Structures
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    • v.1 no.1
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    • pp.21-41
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    • 2010
  • Multi-span steel-concrete composite (SCC) bridges are very sensitive to earthquake loading. Extensive damage may occur not only in the substructures (piers), which are expected to yield, but also in the other components (e.g., deck, abutments) involved in carrying the seismic loads. Current seismic codes allow the design of regular bridges by means of linear elastic analysis based on inelastic design spectra. In bridges with superstructure transverse motion restrained at the abutments, a dual load path behavior is observed. The sequential yielding of the piers can lead to a substantial change in the stiffness distribution. Thus, force distributions and displacement demand can significantly differ from linear elastic analysis predictions. The objectives of this study are assessing the influence of piers-deck stiffness ratio and of soil-structure interaction effects on the seismic behavior of continuous SCC bridges with dual load path, and evaluating the suitability of linear elastic analysis in predicting the actual seismic behavior of these bridges. Parametric analysis results are presented and discussed for a common bridge typology. The response dependence on the parameters is studied by nonlinear multi-record incremental dynamic analysis (IDA). Comparisons are made with linear time history analysis results. The results presented suggest that simplified linear elastic analysis based on inelastic design spectra could produce very inaccurate estimates of the structural behavior of SCC bridges with dual load path.

Correlation of Experimental and Analytical Inelastic Responses of A 1:12 Scale 10-Story Reinforced Concrete Frame-Wall Structure (1:12축소 10층 철근콘크리트 골조-벽식 구조의 비선형 거동에 대한 실험과 해석의 상관성)

  • 이한선;김상호
    • Journal of the Korea Concrete Institute
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    • v.12 no.6
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    • pp.119-126
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    • 2000
  • Reinforced concrete structural walls are widely known to provide an efficient lateral load resistance and drift control. However, many reported researches on them are mostly limited to the RC structural walls reinforced according to seismic details. When the pushover analysis technique is used for the prediction of inelastic behavior of frame-wall structures for the seismic evaluation of existing buildings having non-seismic details, the reliability of this analysis method should be checked by the test results. The objective of this study is to verify the correlation between the experimental and analytical responses of a high-rise reinforced concrete frame-wall structure having non-seismic details by using DRAIN-2DX program[11] and the test results performed previously[1]. It is concluded that the behavior of the frame-wall model is mainly affected by the fixed-end rotation(uplift at base) and bending deformation of the wall and that the analysis with the LINKS model[10] in DRAIN-2DX describes them with good reliability.