• Title/Summary/Keyword: 정적 비선형해석

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Dynamic Factor of Safety Calculation of Slope by Nonlinear Response History Analysis (비선형 응답이력해석을 통한 사면의 동적 안전계수 계산)

  • Lee, Yonghee;Kim, Hak-Sung;Ju, Young-Tae;Kim, Daehyeon;Park, Heon-Joon;Park, Duhee
    • Journal of the Korean Geotechnical Society
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    • v.37 no.9
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    • pp.5-12
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    • 2021
  • Pseudo-static slope stability analysis method is widely used in engineering practice to calculate the seismic factor of safety of slope subjected to earthquake ground motions. Although the dynamic analysis method is well recognized to have the primary advantage of simulating the stress-strain response of soils, it is not often used in practice because of the difficult in estimating the factor of safety. In this study, a procedure which utilizes the dynamic analysis method to extract the transient dynamic factor of safety is devleoped. This method overcomes the major limitation of the pseudo-static method, which uses an empirically determined seismic coefficient to derive the factor of safety. The proposed method is applied to a slope model and the result is compared with that of the pseudo-static method. It is shown that minimum dynamic factor of safety calculated by the dynamic analysis is slightly larger than that determined from the pseudo-static method. It is also demonstrated that the dynamic factor of safety becomes minimum when the horizontal seismic coefficient and horizontal average acceleration are maximum.

Verification of the Torsional Amplification Factor for the Seismic Design of Torsionally Imbalanced Buildings (비틀림 비정형 건물의 내진설계를 위한 우발편심 비틀림 증폭계수 검증)

  • Lee, Kwang-Ho;Jeong, Seoung-Hoon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.14 no.6
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    • pp.67-74
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    • 2010
  • Because of the difference between the actual and computed eccentricity of buildings, symmetrical buildings will be affected by torsion. In provisions, accidental eccentricity is intended to cover the effect of several factors, such as unfavorable distributions of dead- and live-load masses and the rotational component of ground motion about a vertical axis. The torsional amplification factor is introduced to reduce the vulnerability of torsionally imbalanced buildings. The effect of the torsional amplification factor is observed for a symmetric rectangular building with various aspect ratios, where the seismic-force-resisting elements are positioned at a variable distance from the geometrical center in each direction. For verifying the torsional amplification factor in provisions, nonlinear reinforced concrete models with various eccentricities and aspect ratios are used in rock. The difference between the maximum displacements of the flexible edge obtained between using nonlinear static and time-history analysis is very small but the difference between the maximum torsional angles is large.

The Nonlinear Behavior Characteristics of the 3D Mixed Building Structures with Variations in the Lower Stories (입체 복합구조물의 하부골조 층수 변화에 따른 비선형 거동특성)

  • 강병두;전대한;김재웅
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.1
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    • pp.55-62
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    • 2002
  • The upper wall-lower frame structures(mixed building structures) are usually composed of shear wall structure in the upper part of structure which is used as residential space and frame structure in the lower part of structure which is used as commercial space centering around the transfer system in the lower part of structure. These structures are characteristics of stiffness irregularity, mass irregularity, and vertical geometric irregularity. The purpose of this study is to investigate the nonlinear response characteristics and the seismic capacity of mixed building structures when the number of stories in the lower frame is varied. The conclusions of this study are following. 1) As the result of push-over analysis of structure such as roof drift(i.e. roof displacement/structural height) and base shear coefficient, when the stories of lower frame system are increased, base shear coefficient is decreased, but roof drift is increased. 2) According to an increase in stories of the lower fame, story drift and ductility ratio of upper wall system are decreased and behavior of upper wall system is closed to elastic. 3) When the stories of lower frame system are increased, the excessive story drift is concentrated on the lower frame system.

Influence of Analytical Models on the Seismic Response of Modular Structures (모듈러 구조물의 해석 모델이 지진응답에 미치는 영향)

  • Choi, Kyung-Suk;Lee, Ho-Chan;Kim, Hyung-Joon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.2
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    • pp.74-85
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    • 2016
  • Seismic design of modular structures is usually carried out under the assumption that their load-carrying mechanism is similar to that of traditional steel moment-resisting frames(SMRFs). However, the load carry mechanism of modular structures would be different with that of traditional SMRFs because of their overlapped structural elements and complicated details of connections for the assembly of the unit-modules. In this study, nonlinear static analyses of 3 and 5-story prototype modular structures have been carried out with four different analytical models, which are established in consideration for the effects of overlapped elements and the hysteretic behavior of connections. Prototype structures present different lateral stiffness and strength depending on the modeling of overlapped elements and the rotational behavior of connections. For modular structures designed under assumption that overlapped structural elements are fully composite each other and connections between unit-modules are fixed, their lateral strength and stiffness can be over-estimated. Furthermore, it is known from the analysis results that modular structures with more than 3-stories would possess relatively low overstrength compared to traditional SMRFs.

Seismic Performance Evaluation of Piloti-type low-rise RC apartment buildings using Nonlinear Static Analysis (비선형 정적해석을 이용한 필로티형 저층 RC 집합주택의 내진성능평가)

  • Lee, Jeong-Jae;Lee, Han-Seon;Kim, Hee-Cheul;Lee, Young-Hak;Lee, Ki-Hak
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.237-240
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    • 2008
  • The objective of this study is to evaluate the seismic performance of the low-rise RC apartment buildings having piloties at ground level by using nonlinear static analysis with regards to the maximum considered and design earthquakes in Korea. To do this, the target displacement at roof was estimated according to FEMA356 (or ASCE/SEI-41), and the deformations of the critical members were compared with the failure criteria of Life Safety(LS) and Collapse Prevention(CP) given in FEMA356. The conclusions are as follows: (1) columns satisfy criteria of LS and CP, but (2) the shear wall in the longitudinal direction failed to satisfy those of both LS and CP while those in the transverse direction satisfy that of LS, but failed that of CP.

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Reliability of Nonlinear Direct Spectrum Method with Mixed Building Structures (복합구조물에 대한 비선형 직접스펙트럼법의 신뢰성)

  • 강병두;김재웅
    • Journal of the Earthquake Engineering Society of Korea
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    • v.7 no.2
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    • pp.75-84
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    • 2003
  • Most structures are expected to deform beyond the limit of linearly elastic behavior when subjected to strong ground motion. Seismic evaluation of structure requires an estimation of the structural performance in terms of displacement demand imposed by earthquakes on the structure. The nonlinear response history analysis(NRHA) among various nonlinear analysis methods is the most accurate to compute seismic performance of structures, but it is time-consuming and necessitate more efforts. The nonlinear approximate methods, which is more practical and reliable tools for predicting seismic behavior of structures, are extensively studied. Among them, the capacity spectrum method(CSM) is conceptually simple, but the iterative procedure is time-consuming and may sometimes lead to no solution or multiple solutions. This paper considers a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of mixed building structures without iterative computations, given dynamic property T from stiffness skeleton curve and nonlinear pseudo acceleration $A_{y}$/g and/or ductility ratio $\mu$ from response spectrum. The nonlinear response history analysis has been performed and analyzed with various earthquakes for estimation of reliability and practicality of NDSM with mixed building structures.

Evaluation of Seismic Performance of Mixed Building Structures by using the Nonlinear Displacement Mode Method (비선형 변위모드법을 적용한 복합구조물의 내진성능평가)

  • 김부식;송호산
    • Journal of the Earthquake Engineering Society of Korea
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    • v.7 no.6
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    • pp.71-80
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    • 2003
  • Though a nonlinear time history analysis may be provided to estimate more exactly the seismic performance of building structure, approximation methods are still needed in the aspect of practicality and simplicity, In converting a multi-story structure to an equivalent SDOF system, the mode vectors of the multi-story structure are assumed as the mode shape in elastic state regardless of elastic or elastic-plastic state. However, the characteristics of displacement mode are also changed after the yielding made in the structural elements, because the structure becomes inelastic in each incremental load step. In this research, a method of converting MDOF system to ESDOF system is presented by using nonlinear displacement mode considering the mode change of structures after the yielding. Also, the accuracy and efficiency of the method of the nonlinear displacement mode method of the estimate of seismic response of Mixed Building Structures were examined by comparing the displacements of the roof level of the multi-story building structures estimated from this converted displacement response of ESDOF with the displacement of the roof level through the nonlinear dynamic analysis of the multi-story building structures subjected to an actual earthquake excitation.

Prediction Approach with a Stiffness Measure in Nonlinear Dynamic Analysis of Reinforced Concrete Structures (철근 콘크리트 구조물의 비선형 동적 해석을 위한 성치 측정에 의한 예측 접근법)

  • 김교신;전경훈
    • Journal of the Earthquake Engineering Society of Korea
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    • v.1 no.1
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    • pp.1-10
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    • 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.

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Progressive Collapse Resisting Capacity of Building Structures with Infill Steel Panels (강판벽이 설치된 건물의 연쇄붕괴 저항성능)

  • Lee, Ha-Na;Kwon, Kwang-Ho;Kim, Jin-Koo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.1
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    • pp.19-26
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    • 2012
  • In this study the progressive collapse behavior of a moment frame with infill steel panels is evaluated using nonlinear static pushdown analysis. The analysis model is a two story two span structure designed only for gravity load, and the load-displacement relationship is obtained with the center column removed. To obtain local stress and strain as well as the global structural behavior, finite element analysis is conducted using ABACUS. Through the analysis the effect of the span length and the thickness of the steel plate on the progressive collapse behavior of the structure is investigated, and the effect of the dividing the infill panel using stud columns is also studied. According to the analysis results, the thickness of the panels required to prevent progressive collapse increases as the span length increases, and as the number of panel division increases the progressive collapse resisting capacity increases slightly but the effect is not significant. It is also observed that when the infill panel is installed in only a part of the span the progressive collapse resisting capacity is somewhat increased.

A Structural Analysis of the Tracked Vehicle (궤도차량의 차체구조해석)

  • Lee, Young-Shin;Choi, Chang;Jun, Byoung-Hee;Oh, Jae-Moon
    • Computational Structural Engineering
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    • v.10 no.3
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    • pp.145-155
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    • 1997
  • In this study, static and dynamic transient analysis of tracked vehicle structure with recoil impact load is performed for transient impact and traveling load using ANSYS and ABAQUS FEM codes. When transient impact loads are applied at tracked vehicle, the maximum dynamic Von Mises stress occurs between beam stiffener of upper plate and race ring and stress level is about 390-450 MPa. The results of transient analysis shows similar level and tendency with static stress with dynamic force effect of 1.6. The excessive stresses occur around the race ring for the both cases. When the traveling loads are applied on the tracked vehicle, the maximum Tresca stress occurs around suspension #1 and is about 450 MPa and results of static and nonlinear transient analysis are quite similar.

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