• Title, Summary, Keyword: ESDOF

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Seismic Performance Evaluation of Multi-Span Bridges considering Effect of Lateral Load Distributions and Equivalent SDOF methods (횡하중 분포와 등가단자유도 방법의 영향을 고려한 다경간 교량의 내진성능 평가)

  • Song, Jong-Keol;Nam, Wang-Hyun;Chung, Yeong-Hwa
    • Journal of Industrial Technology
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    • v.26 no.A
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    • pp.163-171
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    • 2006
  • To evaluate inelastic seismic responses of multi-span-bridge, the equivalent single-degree-of-freedom (ESDOF) methods and the lateral load distributions are applied to the capacity spectrum method(CSM). From the pushover analysis results using the four ESDOF methods and the six types lateral load distributions, the ESDOF method more than lateral load distribution is found to have an important influence upon the pushover analysis. The effects of the higher mode on the bridge seismic behaviors are also increased as the number of pier increase. Therefore, it can be concluded that lateral load distributions and ESDOF methods for reflection of higher mode effects should be considered in the seismic analysis of the bridge structural.

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Comparison of Energy Demand in Multi-Story Buckling Restrained Braced Frame and Equivalent SDOF System (다층 비좌굴 가새골조와 등가 단자유도계의 에너지 요구량의 비교)

  • 김진구;원영섭
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.16 no.2
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    • pp.173-182
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    • 2003
  • In equivalent static nonlinear analysis and in energy-based design, the structures are generally transformed into an equivalent SDOF system. In this study the seismic energy demands in multi story structures, such as three-, eight-, and twenty-story steel moment-resisting frames(MRF), buckling restrained braced frames(BRBF) and a damage tolerant braced frame(DTBF), are compared with those of equivalent single degree of freedom(ESDOF) systems. Sixty earthquake ground motions recorded In different soil conditions, which are soft rock, soft soil, and neat fault, were used to compute the input and hysteretic energy demands in model structures. In case the modal mass coefficient is less than 0.8, the effects of higher modes are considered in the process of converting into ESDOF According to the analysis results, the hysteretic and input energies obtained from 3 story and 8 story MRF and DTBF agreed well with the results from analysis of equivalent SDOF systems. However in the 20 story BRBF the results from ESDOF underestimated those obtained from the original structures.

Nonlinear Static Analysis for Seismic Performance Evaluation of Multi-Span Bridges Considering Effect of Equivalent SDOF Methods (등가단자유도 방법의 영향을 고려한 다경간 교량의 내진성능 평가를 위한 비탄성 정적해석)

  • Song, Jong-Keol;Nam, Wang-Hyun;Chung, Yeong-Hwa
    • Journal of The Korean Society of Civil Engineers
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    • v.26 no.3A
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    • pp.473-484
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    • 2006
  • The capacity spectrum method (CSM) can be used to simply estimate the maximum displacement response of the nonlinear structures. To evaluate seismic performance of multi-span bridges using the CSM, the representative response for structural system should be derived from the multi-degree-of-freedom (MDOF) responses by using the equivalent single-degree-of-freedom (ESDOF) method. The ESDOF method is used to calculate the capacity curve of the structural system from the pushover curves of all piers or structural members estimated by the pushover analysis. In order to evaluate an accuracy of ESDOF methods used in the CSM, the maximum displacements estimated by the CSM incorporating the several ESDOF methods are compared to those by the inelastic time-history analysis for several artificial earthquakes corresponding to the design spectrum.

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Evaluation of Inelastic Displacement Response for Multi-Span Bridge Structures Subjected to Earthquakes (지진하중에 대한 다경간 교량의 비탄성 변위응답 평가)

  • Song, Jong-Keol;Nam, Wang-Hyun;Chung, Yeong-Hwa
    • Journal of Industrial Technology
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    • v.24 no.A
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    • pp.195-204
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    • 2004
  • To evaluate inelastic seismic responses of multi-span bridge structures, the capacity spectrum method(CSM) incorporating the equivalent single-degree-of freedom(ESDOF) method is presented. Application of the CSM incorporating the ESDOF method is illustrated by example analysis for symmetric and asymmetric bridge structures. To investigate an accuracy of the CSM, the maximum displacements estimated by the CSM are compared to those by inelastic time history analysis for several artificial earthquakes. The results show that the CSM provided conservative estimates of the maximum displacements for the symmetric and asymmetric bridge structures, and the trend of conservative estimates of the asymmetric bridge structures was significantly larger than that of the symmetric bridge structure.

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Evaluation of Seismic Response of Multi-Degree of Freedom Bridge Structures According to The ESDOF Method (등가단자유도 방법에 따른 다자유도 교량의 지진응답평가)

  • Song, Jong-Keol;Nam, Wang-Hyun;Chung, Yeong-Hwa
    • Journal of Industrial Technology
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    • v.25 no.A
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    • pp.23-30
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    • 2005
  • The capacity spectrum method(CSM) can be used for the evaluation of inelastic maximum response of structures and has been recently used in the seismic design using the incorporation of pushover analysis and response spectrum method. To efficiently evaluate seismic performance of multi-degree-of freedom(MDOF) bridge structures, it is important that the equivalent response of MDOF bridge structures should be calculated. To calculate the equivalent response of MDOF system, equivalent responses are obtained by using Song method, Fajfar method and Calvi method. Also, those responses are applied to CSM method and seismic performance of bridge according to the ESDOF method are compared and evaluated straightforwardly.

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Seismic vulnerability assessment of confined masonry buildings based on ESDOF

  • Ranjbaran, Fariman;Kiyani, Amir Reza
    • Earthquakes and Structures
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    • v.12 no.5
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    • pp.489-499
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    • 2017
  • The effects of past earthquakes have demonstrated the seismic vulnerability of confined masonry structures (CMSs) to earthquakes. The results of experimental analysis indicate that damage to these structures depends on lateral displacement applied to the walls. Seismic evaluation lacks an analytical approach because of the complexity of the behavior of this type of structure; an empirical approach is often used for this purpose. Seismic assessment and risk analysis of CMSs, especially in area have a large number of such buildings is difficult and could be riddled with error. The present study used analytical and numerical models to develop a simplified nonlinear displacement-based approach for seismic assessment of a CMS. The methodology is based on the concept of ESDOF and displacement demand and is compared with displacement capacity at the characteristic period of vibration according to performance level. Displacement demand was identified using the nonlinear displacement spectrum for a specified limit state. This approach is based on a macro model and nonlinear incremental dynamic analysis of a 3D prototype structure taking into account uncertainty of the mechanical properties and results in a simple, precise method for seismic assessment of a CMS. To validate the approach, a case study was considered in the form of an analytical fragility curve which was then compared with the precise method.

Seismic Performance Evaluation of Building Structures Using Modified Capacity Spectrum (수정된 능력스펙트럼을 이용한 건축구조물의 내진성능평가)

  • 최원호
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.267-274
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    • 2000
  • Current seismic design codes for building structures are based on the method which can provide enough capacity to satisfy objected performance level and exactly evaluate the seismic performance of buildings. The capacity spectrum method using the nonlinear static(pushover) analysis is becoming a popular tool for evaluating the seismic performance of existing and new building structures. By means of a graphical procedure capacity spectrum method esimates the performance level of structure by comparing the capacity of structure with the demand of earthquake ground motion on the structure. In the method the relation between base shear estimated by a nonlinear static analysis and horizontal displacement is used. Capacity spectrum is usually expressed as what represent the responses of the equivalent single degree of freedom (ESDOF) system for the building structures. However there are some problems in converting procedures into ESDOF system which include not considering the effect of higher modes of structures. The objective of this paper is to compare and verify existing methods and suggest the modified capacity spectrum for seismic performance evaluation of building structures.

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Modeling of the Spatial Structures for Dynamic Analysis and Evaluation of Performance Point Based on Capacity Spectrum Method (동적해석을 위한 대공간 구조물의 모델링 및 능력스펙트럼법에 의한 성능점 산정)

  • Kan, Eun-Young;Lee, Sang-Ju;Han, Sang-Eul
    • Proceeding of KASS Symposium
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    • pp.49-57
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    • 2006
  • Performance based seismic design is a very efficient method in evaluating the seismic capacity of building. In this study, the method estimating the performance point of the spatial structures based on capacity spectrum method(CSM) is proposed. And for efficient evaluation for the performance point of the spatial structures, the algorithm to convert spatial structural system to ESDOF system is proposed. Its efficiency is confirmed by comparing with time history analysis of full model. And dynamic behaviors of spatial structures are examined by using this method. At last, evaluation of structural performance according to variation of stiffness after plastic deformation is carried out.

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A Study on Evaluation of Performance Point for the Latticed Dome (래티스 돔의 성능점 산정에 관한 연구)

  • Han Sang-Eul;Lee Sang-Joo;Gan Eun-Young
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.317-324
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    • 2006
  • Performance-based design concept is needed to evaluate the seismic capacity of building. In this study, the method estimating the performance point of the spatial structures based on capacity spectrum method (CSM) is proposed. And for efficient evaluation for the performance point of the spatial structures, the algorithm to convert spatial structural system to ESDOF system is simulated Its efficiency is confirmed by comparing with time history analysis of full model. And dynamic behaviors of spatial structures are examined by using this method. At last, evaluation of structural performance according to variation of stiffness after plastic deformation on the substructures is carried out.

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Seismic Damage Analysis of Large Steel Structures (대형강구조물의 지진손상도 해석)

  • 송종걸
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.199-206
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    • 1997
  • Under sever earthquake, structural elements or structures may sustain a large number of inelastic excursions. To predict seismic damage of the structures with accuracy, much research for general definition of structural collapse and seismic damage analysis is required. The ductility method, the energy method and Park and Ang method for seismic damage analysis of structural elements and structures are compared in this paper. Also, the seismic damage analysis for system-level of structure is carried out using the ESDOF-system method and Powell method. To compare tendency of the seismic damage analysis using each methods, example analysis is accomplished for several cases of different structures and different earthquake excitation.

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