• 제목/요약/키워드: inelastic structure

검색결과 333건 처리시간 0.021초

Seismic Retrofit Design Procedure Using a Friction Damper (마찰 감쇠기를 사용한 구조물의 보강 설계법 제안)

  • Moon, Ki-Hoon;Han, Sang-Whan;Jo, Han-Chul;Lee, Kang-Seok
    • Journal of the Earthquake Engineering Society of Korea
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    • 제15권6호
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    • pp.45-53
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    • 2011
  • The purpose of this study was to propose a design procedure for a damped structure with a friction damper for an existing structure. The target displacement of the damped structure was determined using the maximum displacement of the existing structure. The displacement of the damped structures was predicted using a proposed equation for the inelastic displacement ratio. For this study, we conducted a nonlinear response history analysis using 80 earthquake ground motions to verify the validity of the proposed design procedure by comparing the responses of the damped and undamped structures. Based on the dynamic analysis results, it was concluded that the predicted displacement of the damped structure using the proposed design procedure matched well with the analysis results.

Direct Inelastic Earthquake Design Using Secant Stiffness (할선강성을 이용한 직접비탄성내진설계)

  • 박홍근;엄태성
    • Journal of the Earthquake Engineering Society of Korea
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    • 제8권1호
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    • pp.17-27
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    • 2004
  • A new earthquake design method performing iterative calculations using secant stiffness was developed. The proposed design method has the advantages of convenience and stability in numerical analysis because it uses elastic analysis. At the same time, the proposed design method can accurately estimate the strength and ductility demands on the members because it performs the analysis on the inelastic behavior of structure using iterative calculation. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. Design examples using the proposed method were presented, and its advantages were presented by the comparisons with existing design methods using elastic or inelastic analysis. The proposed design method, as an integrated method of analysis and design, can address the earthquake design strategy devised by the engineer. such as ductility limit on each member, the design concept of strong column - weak beam, and etc. In addition, through iterative calculations on the structure preliminarily designed only with member sizing, the strength and ductility demands of each member can be directly calculated so as to satisfy the given design strategy. As the result. economical and safe design can be achieved.

Seismic Safety Assessment of Long Period Structures Base on Elastic/Inelastic Response Characteristics (장주기구조물의 탄소성응답특성을 고려한 지진안전성 평가)

  • Bang, Myung-Seok
    • Journal of the Korean Society of Safety
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    • 제26권3호
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    • pp.52-58
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    • 2011
  • The earthquake characteristic assessment of social overhead facilities would be an important examination issue for seismic capacity enhancement. This study is intended to reasonably evaluate the structural behavior of longperiod frame structures considering near-fault and far-fault earthquake characteristics. Elastic/inelastic time history analyses were performd by selecting the objective structure which can precisely reflect the effect of input ground motion. Based on the result of numerical analysis, we have investigated response aspects of shear force, moment, acceleration and displacement according to earthquake characteristics. Moreover, in order to understand the inelastic behavior of the objective structure, we have analyzed and compared collapse modes by considering the occurrence process of plastic hinges. The outcome of this research is expected to provide the basic information for the seismic safety assessment of long-period frame structures.

Vibration Control of Shear Wall-Frame System using Energy Dissipation Devices (에너지 소산형 감쇠기를 이용한 철근콘크리트 전단벽-골조 시스템의 진동제어)

  • Park, Ji-Hun;Kim, Gil-Hwan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 한국소음진동공학회 2007년도 춘계학술대회논문집
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    • pp.578-581
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    • 2007
  • In this study, the seismic control performance of energy dissipation devices installed in a shear all-frame structure is investigated through nonlinear time history analysis of a 12-story building. Inelastic shear walls are modeled using the multiple vertical line element model (MVLEM) and inelastic columns and girders were modeled using fiber beam elements. For a seismic load increased by 38% compared to the design load, the seismic control performance was analyzed based on the results of a nonlinear time history analysis in terms of the inter-story drift, the story shear and the flexural strain. Friction type dampers was found to performs best if they are installed in the form of a brace adjacent to the shear wall with the friction force of 15 % of the maximum story shear force induced in the original building structure without dampers.

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Damping and frequency changes induced by increasing levels of inelastic seismic demand

  • Aguirre, Diego A.;Montejo, Luis A.
    • Smart Structures and Systems
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    • 제14권3호
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    • pp.445-468
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    • 2014
  • The objective in this research is to determine the feasibility of using changes on the dynamic properties of a reinforced concrete (RC) structure to identify different levels of seismic induced damage. Damping ratio and natural frequency changes in a RC bridge column are analyzed using different signal processing techniques like Hilbert Transforms, Random Decrement and Wavelet Transforms. The data used in the analysis was recorded during a full-scale RC bridge column shake table test. The structure was subjected to ten earthquake excitations that induced different levels of inelastic demand on the column. In addition, low-intensity white noises were applied to the column in-between earthquakes. The results obtained show that the use of the damping ratio and natural frequency of vibration as damage indicators is arguable.

The Application of a Nonlinear Direct Spectrum Method for Mixed Building Structure (복합구조물에 대한 비선형 직접스펙트럼법의 적용)

  • 강병두;박진화;전대한;김재웅
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 한국지진공학회 2002년도 추계 학술발표회 논문집
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    • pp.258-265
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    • 2002
  • Most structures are expected deform nonlinear and inelastic behavior when subjected to strong ground motion. Nonlinear time history analysis(NTHA) is the most rigorous procedure to compute seismic performance in the various inelastic analysis methods. But nonlinear analysis procedures necessitate more reliable and practical tools for predicting seismic behavior of structures. Some building codes propose the capacity spectrum method. This method is the concept of an equivalent linear system, wherein a linear system having reduced stiffness and increased damping is used to estimate the response of the nonlinear system. This procedure are conceptually simple, but the iterative procedure is time-consuming and may sometimes lead to no solution or multiple solutions. This paper presents a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of structures, without iterative computations, given by the structural initial elastic period and yield strength from the pushover analysis, especially for mixed building structure.

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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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    • 한국지진공학회 2005년도 학술발표회 논문집
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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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Modal Combination Method Considering Higher Mode Effects (고차모드 효과를 고려한 모드조합법)

  • Eom, Tae-Sung;Lee, Hye-Rin;Park, Hong-Gun
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 한국지진공학회 2005년도 학술발표회 논문집
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    • pp.185-192
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    • 2005
  • Using existing static methods, it is possible to estimate accurately the reponses of structures governed by the fundamental mode. However, these methods do not provide reliable estimates for the structure where higher mode effects are significant. Parametric study was performed to analyze the dynamic characteristics of the structure with long vibration period. Based on the investigations, a new modal combination method using modal combination coefficients, Factored Modal Combination, was developed, and static earthquake load patterns addressing higher mode effects reasonably were proposed. Existing modal combination methods, such as SRSS and CQC, lack a theoretical basis to be applied to inelastic structures. In contrast, the proposed method can be applied conveniently in inelastic range as well as in elastic range.

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Error Analysis of Nonlinear Direct Spectrum Method to Various Earthquakes (다양한 지진에 따른 비선형 직접스펙트럼법의 오차해석)

  • 강병두;박진화;전대환;김재웅
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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    • pp.53-60
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    • 2002
  • It has been recognized that damage control must become a more explicit design consideration. In an effort to develop design methods based on performance it is clear that the evaluation of the inelastic response is required. The methods available to the design engineer today are nonlinear time history analyses, or monotonic static nonlinear analyses, or equivalent static analyses with simulated inelastic influences. Some codes proposed the capacity spectrum method based on the nonlinear static(pushover) analysis to determine earthquake-induced demand given the structure pushover curve. This procedure is conceptually simple but iterative and time consuming with some errors. This paper presents a nonlinear direct spectrum method to evaluate seismic Performance of structure, without iterative computations, given the structural initial elastic period and yield strength from the pushover analysis, especially for multi degree of freedom structures. The purpose of this paper is to investigate accuracy and confidence of this method from a point of view of various earthquakes and unloading stiffness degradation parameters.

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Direct Earthquake Design Using Secant Stiffness (할선강성을 이용한 직접내진설계)

  • 박홍근;엄태성
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 한국지진공학회 2003년도 추계 학술발표회논문집
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    • pp.239-246
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    • 2003
  • A new earthquake design method performing iterative calculations using secant stiffness was developed. The proposed design method has the advantages of convenience and stability in numerical analysis because it uses elastic analysis. At the same time, the proposed design method can accurately estimate the strength and ductility demands on the members because it performs the analysis on the inelastic behavior of structure using iterative calculation. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. Design examples using the proposed method were presented, and its advantages were presented by the comparisons with existing design methods using elastic or inelastic analysis. The proposed design method, as an integrated method of analysis and design, can address the earthquake design strategy devised by the engineer, such as ductility limit on each member, the design concept of strong column - weak beam, and etc. Through iterative calculations on the structure preliminarily designed only with member sizing, the strength and ductility demands of each member can be directly calculated so as to satisfy the given design strategy As the result economical and safe design can be achieved.

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