• Title/Summary/Keyword: nonlinear earthquake analysis

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Dynamic Nonlinear Analysis of Marine Cables Under Wave Force and Earthquake Force (파랑하중 및 지진하중을 받는 해양케이블의 동적 비선형 해석)

  • 김문영
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1999.04a
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    • pp.292-299
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    • 1999
  • In order to investigate dynamic behaviors of marine cables under wave and earthquake forces a geometric nonlinear. F, E formulation of marine cables is presented and tangent stiffness and mass matrices for the isoparametric cable element are derived, The initial equilibrium state of cables subjected to self -weights and current forces is determined and free vibration and dynamic nonlinear analysis of cable structures under additional environmental loads are performed based on the initial configuration Challenging examples are presented and discussed in order to demonstrate the feasibility of the present finite element method and investigate dynamic nonlinear behaviors of marine cables.

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Effect of Earthquake characteristics on seismic progressive collapse potential in steel moment resisting frame

  • Tavakoli, Hamid R.;Hasani, Amir H.
    • Earthquakes and Structures
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    • v.12 no.5
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    • pp.529-541
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    • 2017
  • According to the definition, progressive collapse could occur due to the initial partial failure of the structural members which by spreading to the adjacent members, could result in partial or overall collapse of the structure. Up to now, most researchers have investigated the progressive collapse due to explosion, fire or impact loads. But new research has shown that the seismic load could also be a factor for initiation of the progressive collapse. In this research, the progressive collapse capacity for the 5 and 15-story steel special moment resisting frames using push-down nonlinear static analysis, and nonlinear dynamic analysis under the gravity loads specified in the GSA Guidelines, were studied. After identifying the critical members, in order to investigate the seismic progressive collapse, the 5-story steel special moment resisting frame was analyzed by the nonlinear time history analysis under the effect of earthquakes with different characteristics. In order to account for the initial damage, one of the critical columns was weakened at the initiation of the earthquake or its Peak Ground Acceleration (PGA). The results of progressive collapse analyses showed that the potential of progressive collapse is considerably dependent upon location of the removed column and the number of stories, also the results of seismic progressive collapse showed that the dynamic response of column removal under the seismic load is completely dependent on earthquake characteristics like Arias intensity, PGA and earthquake frequency contents.

3D Nonlinear Seismic Analysis of a Bridge Using Fiber Element (섬유요소를 이용한 교량의 3차원 지진해석)

  • 조정래;곽임종;조창백;김병석;김영진
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2002.09a
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    • pp.141-146
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    • 2002
  • In the present design concept, the nonlinear behavior of bridges is allowed under large earthquake. Therefore, demands for nonlinear analyses of bridges are increased more and more especially in the area of seismic assessment. It is, however, difficult to solve the problem how the nonlinearity of columns should be modelled. In this study, the fiber element Is adopted for model ins pier column. The element is a kind of structural elements like frame element, and it can model the distributed plasticity of plastic hinge. A 3 span continuos bridge is taken for seismic analysis. First, the nonlinear static analysis the column at fixed support are performed so that the characteristics of column is investigated. Second, the nonlinear dynamic analyses of the full bridge model is performed, considering 3 directional earthquake excitations.

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Nonlinear Pushover Analysis Considering Higher Mode Effects (고차모드의 효과를 고려한 비선형정적평가방법)

  • Eom, Tae-Sung;Lee, Hye-Rin;Park, Hong-Gun
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2005.03a
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    • pp.153-160
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    • 2005
  • A new nonlinear static analysis method, Effective Modal Pushover Analysis (EMPA) which can evaluate earthquake responses such as story drift and plastic rotation of plastic hinges addressing higher mode effects was developed. Unlike existing nonlinear static procedure based on properties of fundamental vibration mode, the EMPA performs nonlinear static analysis using multiple effective modes constructed by direct combination of natural vibration modes. Therefore higher mode effects can be efficiently considered. In the present study, procedures of the EPMA evaluating inelastic earthquake responese were established and the results were verified by nonlinear time history analysis. The EMPA can be applied to seismic evaluation of high-rise buildings and irregular buildings where higher mode effects become conspicuous.

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Dynamic Stability Analysis of Base-Isolated Low-level Nonlinear Structure Under Earthquake Excitation (지진시 저층건물 면진구조의 비선형 동적 거동)

  • Mun, Byeong-Yeong;Gang, Gyeong-Ju;Gang, Beom-Su;Kim, Gye-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.11
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    • pp.1743-1750
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    • 2001
  • This paper presents an analysis of nonlinear response of the seismically isolated structure against earthquake excitation to evaluate isolation performances of a rubber bearing. In the analysis of the vibration of building, the building is modeled by lumped mass system where the restoring force is considered as linear, bilinear and trilinear. Fundamental equations of motion are derived for the base isolated structure, and hysteretic and nonlinear-elastic characteristics are considered for a numerical calculation. The excitation levels are magnified fur the recorded strong earthquake motions in order to examine dynamic stability of the structure. Seismic responses (of the building are compared fur the each restoring force type. As a result, it is shown that the effect of the motion by the nonlinear response of the building is comparatively not so large from a seismic design standpoint. The responses of the isolated structures reduce sufficiently and controled the motion of the building well in a practical range. By increasing the acceleration of the earthquake, the yielding of the farce was occurred in the concrete and steel frame, which shows the necessity of the exact nonlinear dynamic analysis.

Determination of earthquake safety of RC frame structures using an energy-based approach

  • Merter, Onur;Ucar, Taner;Duzgun, Mustafa
    • Computers and Concrete
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    • v.19 no.6
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    • pp.689-699
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    • 2017
  • An energy-based approach for determining earthquake safety of reinforced concrete frame structures is presented. The developed approach is based on comparison of plastic energy capacities of the structures with plastic energy demands obtained for selected earthquake records. Plastic energy capacities of the selected reinforced concrete frames are determined graphically by analyzing plastic hinge regions with the developed equations. Seven earthquake records are chosen to perform the nonlinear time history analyses. Earthquake plastic energy demands are determined from nonlinear time history analyses and hysteretic behavior of earthquakes is converted to monotonic behavior by using nonlinear moment-rotation relations of plastic hinges and plastic axial deformations in columns. Earthquake safety of selected reinforced concrete frames is assessed by using plastic energy capacity graphs and earthquake plastic energy demands. The plastic energy dissipation capacities of the frame structures are examined whether these capacities can withstand the plastic energy demands for selected earthquakes or not. The displacements correspond to the mean plastic energy demands are obtained quite close to the displacements determined by using the procedures given in different seismic design codes.

Earthquake Response Analysis of Soil-Structure Interaction Systems considering Nonlinear Soil Behavior (지반의 비선형을 고려한 지반-구조물 상호작용계의 지진응답해석)

  • 이종세;최준성;임동철
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2000.10a
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    • pp.361-368
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    • 2000
  • This paper demonstrates how nonlinear soil behavior in a soil-structure interaction system can be realistically incorporated by using a hybrid method in a nonlinear time-domain analysis. The hybrid method employs a general-purpose nonlinear finite element program coupled with a linear SSI program for the unbounded layered soil medium In order to verify the validity and applicability of the hybrid method, nonlinear earthquake response analyses are carried out for the Hualien free-field problem, in which the ground and underground accelerations were measured during several earthquake events, and for a 2-D subway station. It is found that the nonlinear earthquake responses predicted for the Hualien free-field using the hybrid method compare very well with the observed responses whereas the subway station example gives reasonable results.

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Seismic Object Performance Evaluation of Braced Steel Moment Resisting Frames with Low Rise Building under Different Site Stiffness (지반강성을 고려한 중저층 가새모멘트저항골조의 내진 목표성능평가)

  • Kim, Soo Jung;Choi, Byong Jeong;Park, Ho Young;Lee, Jinwoo
    • Journal of the Earthquake Engineering Society of Korea
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    • v.20 no.2
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    • pp.91-101
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    • 2016
  • This study is the compared seismic performance that are difference between the performance of structures on various site classes and beam-column connection. this analysis model was designed the previous earthquake load. To compare the performance levels of the structure was subjected to nonlinear static and nonlinear dynamic analysis. Nonlinear analysis was used to The Perform 3D program. Nonlinear static analysis was compared with the performance point and Nonlinear dynamic analysis was compared the drift ratio(%). Analysis results, the soft site class of the displacement was more increase than rock site classes of the displacement. Also The smaller the displacement was increased beam-column connection stiffness.

Random Vibration Analysis of Nonlinear Structure System using Perturbation Method

  • Moon, Byung-Young;Kang, Beom-Soo;Kang, Gyung-Ju
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2001.09a
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    • pp.243-250
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    • 2001
  • Industrial machines are sometimes exposed to the danger of earthquake. In the design of a mechanical system, this factor should be accounted for from the viewpoint of reliability. A method to analyze a complex nonlinear structure system under random excitation is proposed. First, the actual random excitation, such as earthquake, is approximated to the corresponding Gaussian process far the statistical analysis. The modal equations of overall system are expanded sequentially. Then, the perturbed equations are synthesized into the overall system and solved in probabilistic way. Several statistical properties of a random process that are of interest in random vibration applications are reviewed in accordance with nonlinear stochastic problem. The obtained statistical properties of the nonlinear random vibration are evaluated in each substructure. Comparing with the results of the numerical simulation proved the efficiency of the proposed method.

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Investigation of Structural Damage in Bearing Wall Buildings with Pilotis by 2017 Pohang Earthquake (2017 포항지진에 의한 필로티형 내력벽건물의 구조손상 분석)

  • Eom, Tae Sung;Lee, Seung Jae;Park, Hong Gun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.23 no.1
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    • pp.9-18
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    • 2019
  • In 2017 Pohang Earthquake, a number of residential buildings with pilotis at their first level were severely damaged. In this study, the results of an analytical investigation on the seismic performance and structural damage of two bearing wall buildings with pilotis are presented. The vibration mode and lateral force-resisting mechanism of the buildings with vertical and plan irregularity were investigated through elastic analysis. Then, based on the investigations, methods of nonlinear modeling for walls and columns at the piloti level were proposed. By performing nonlinear static and dynamic analyses, structural damages of the walls and columns at the piloti level under 2017 Pohang Earthquake were predicted. The results show that the area and arrangement of walls in the piloti level significantly affected the seismic safety of the buildings. Initially, the lateral resistance of the piloti story was dominated mainly by the walls resisting in-plane shear. After shear cracking and yielding of the walls, the columns showing double-curvature flexural behavior contributed significantly to the residual strength and ductility.