• Title/Summary/Keyword: pushover analysis

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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
    • KSCE Journal of Civil and Environmental Engineering Research
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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.

Comparison of Performance Evaluation Methods Based on the Estimation of Nonlinear Seismic Responses for Multistory Building (건축구조물의 비선형 지진응답 산정을 위한 내진성능평가 방법의 비교)

  • 최원호;이동근
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2002.03a
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    • pp.349-356
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    • 2002
  • There has been an increasing trend toward the use of pushover analysis as a tool for evaluating the seismic resistant and safety of a building structure in the performance based earthquake engineering field. The ATC-40 document proposed a nonlinear static procedure based on the Capacity Spectrum Method to determine earthquake-induced demand given the structure pushover curve, which a curve representing base shear versus roof displacement. However, the procedure is conceptually simple, iterative and time consuming method and may sometimes lead to no solution or multiple solutions. A new improved method of seismic performance evaluation for moment frame building, which take into account the previously mentioned deficiencies of currently used elastic design procedures, is presented in this paper. The results of nonlinear static and nonlinear time history analysis of an example high-rise steel moment frame designed by the proposed method are presented and discussed.

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Seismic retrofitting of a tower with shear wall in UHPC based dune sand

  • Trabelsi, Abderraouf;Kammoun, Zied;Beddey, Aouicha
    • Earthquakes and Structures
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    • v.12 no.6
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    • pp.591-601
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    • 2017
  • To prevent or limit the damage caused by earthquakes on existing buildings, several retrofitting techniques are possible. In this work, an ultra high performance concrete based on sand dune has been formulated for use in the reinforcement of a multifunctional tower in the city of Skikda in Algeria. Tests on the formulated ultra high performance concrete are performed to determine its characteristics. A nonlinear dynamic analysis, based on the "Pushover" method was conducted. The analysis allowed an optimization of the width of reinforced concrete walls used in seismic strengthening. Two types of concrete are studied, the ordinary concrete and the ultra high performance concrete. Both alternatives are compared with the reinforcement with carbon fibers and by base isolation retrofit design.

The beneficial effects of beam web opening in seismic behavior of steel moment frames

  • Erfani, Saeed;Naseri, Ata Babazadeh;Akrami, Vahid
    • Steel and Composite Structures
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    • v.13 no.1
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    • pp.35-46
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    • 2012
  • Implementation of openings in beams web has been introduced as an innovative method for improving seismic performance of steel moment frames. In this paper, several steel moment frames have been studied in order to evaluate the effect of openings in beams web. The beam sections with web opening have been modeled as a simplified super-element to be used in designing frames and to determine opening configurations. Finite element models of designed frames were generated and nonlinear static pushover analysis was conducted. The efficient location for openings along the beam length was discovered and the effects of beams with web openings on local and global behavioral characteristics of frames were discussed. Base on the results, seismic performance of steel moment frames was improved by creating openings in beams web, in terms of reduction in stress level of frame sensitive areas such as beam to column connections and panel zones.

Effects of confinement reinforcement and concrete strength on nonlinear behaviour of RC buildings

  • Yon, Burak;Calayir, Yusuf
    • Computers and Concrete
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    • v.14 no.3
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    • pp.279-297
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    • 2014
  • This paper investigates the effects of confinement reinforcement and concrete strength on nonlinear behaviour of reinforced concrete buildings (RC). For numerical application, an eleven-storey and four bays reinforced concrete frame building is selected. Nonlinear incremental static (pushover) analyses of the building are performed according to various concrete strengths and whether appropriate confinement reinforcement, which defined in Turkish seismic code, exists or not at structural elements. In nonlinear analysis, distributed plastic hinge model is used. As a result of analyses, capacity curves of the frame building and moment-rotation curves at lower end sections of ground floor columns are determined. These results are compared with each other according to concrete strength and whether appropriate confinement reinforcement exists or not, respectively. According to results, it is seen that confinement reinforcement is important factor for increasing of building capacity and decreasing of rotations at structural elements.

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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The soil effect on the seismic behaviour of reinforced concrete buildings

  • Yon, Burak;Calayir, Yusuf
    • Earthquakes and Structures
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    • v.8 no.1
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    • pp.133-152
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    • 2015
  • This paper investigates the soil effect on seismic behaviour of reinforced concrete (RC) buildings by using the spread plastic hinge model which includes material and geometric nonlinearity of the structural members. Therefore, typical reinforced concrete frame buildings are selected and nonlinear dynamic time history analyses and pushover analyses are performed. Three earthquake acceleration records are selected for nonlinear dynamic time history analyses. These records are adjusted to be compatible with the design spectrum defined in Turkish Seismic Code. Interstory drifts and damages of selected buildings are compared according to local soil classes. Also, capacity curves of these buildings are compared with maximum responses obtained from nonlinear dynamic time history analyses. The results show that, soil class influences the seismic behaviour of reinforced concrete buildings, significantly.

Confinement effect on the behavior factor of dual reinforced concrete moment-resisting systems with shear walls

  • Alireza Habibi;Mehdi Izadpanah;Yaser Rahmani
    • Structural Engineering and Mechanics
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    • v.85 no.6
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    • pp.781-791
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    • 2023
  • Lateral pressure plays a significant role in the stress-strain relationship of compressed concrete. Concrete's internal cracking resistance, ultimate strain, and axial strength are improved by confinement. This phenomenon influences the nonlinear behavior of reinforced concrete columns. Utilizing behavior factors to predict the nonlinear seismic responses of structures is prevalent in seismic codes, and this factor plays a vital role in the seismic responses of structures. This study aims to evaluate the confining action on the behavior factor of reinforced concrete moment resisting frames (RCMRFs) with shear walls (SWRCMRFs). To this end, a diverse range of mid-rise SW-RCMRFs was initially designed based on the Iranian national building code criteria. Second, the stress-strain curve of each element was modeled twice, both with and without the confinement phenomenon. Each frame was then subjected to pushover analysis. Finally, the analytical behavior factors of these frames were computed and compared to the Iranian seismic code behavior factor. The results demonstrate that confining action increased the behavior factors of SW-RCMRFs by 7-12%.

Inelastic Time History Analysis of an Unbraced 5-Story Steel Framed Structure for Arrangement of Semi-Rigid Connection (반강접 접합부 배치에 따른 비가새 5층 철골골조구조물의 비탄성 시간이력해석)

  • Kang, Suk-Bong;Kim, Sin-Ae
    • Journal of Korean Society of Steel Construction
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    • v.22 no.4
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    • pp.313-324
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    • 2010
  • In this study, an unbraced five-story steel-framed structure was designed in accordance with KBC2005 to understand the features of structural behavior for the arrangement of semi-rigid connections. An inelastic time history analysis of structural models was performed, wherein all the connections were idealized as fully rigid and semi-rigid. Additionally, horizontal and vertical arrangements of semi-rigid connections were used for the models. A fiber model was utilized for the moment-curvature relationship of a steel beam and a column, a three-parameter power model for the moment-rotation angle of the semi-rigid connection, and a three-parameter model for the hysteretic behavior of a steel beam, column, and connection. The base-shear force, top displacement, story drift, required ductility for the connection, maximum bending moment of the column, beam, and connection, and distribution of the plastic hinge were investigated using four earthquake excitations with peak ground acceleration for a mean return period of 2,400 years and for the maximum base-shear force in the pushover analysis of a 5% story drift. The maximum base-shear force and story drift decreased with the outer vertical distribution of the semi-rigid connection, and the required ductility for the connection decreased with the higher horizontal distribution of the semi-rigid connection. The location of the maximum story drift differed in the pushover analysis and the time history analysis, and the magnitude was overestimated in the pushover analysis. The outer vertical distribution of the semi-rigid connection was recommended for the base-shear force, story drift, and required ductility for the connection.

Design of Lateral Load Resisting System using Nonlinear Static Analysis (비선형 정적해석을 통한 횡저항 시스템의 보유성능 평가 및 설계방안 연구)

  • Song, Jin-Gyu;Kim, Geon-Woo;Jung, Sung-Jin;Song, Young-Hoon;Lee, Seung-Chang
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.1 s.47
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    • pp.9-16
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    • 2006
  • The design practice of the lateral resisting system has been traditionally dependent on the experience and know-how of a structural engineer. And the method to reflect the evaluation results of building's capacity on design process doesn't exist. The proposal of a rational design of the lateral load resisting system is based on the available full capacity (Rac) of a building and the minimum required capacity (Rcode) suggested in the code. This study suggests thai nonlinear static analysis, which is the estimation of the lateral capacity with the pushover analysis, be included in the existing design procedure of the structure. After finishing the basic structural design, the lateral resisting capacity ol a building is estimated. At the phase of nonlinear static analysis, pushover analysis is peformed to define the fully yielded baseshear (VY). When the design wind baseshear (Vwind) is bigger than the design seismic baseshear (VD), the value is checked to determine whether or not it is smaller than the VY. After confirming that it is smaller, the Rac of the structure is computed. If the VD is bigger at first, only the Rac is computed. When the value of the estimation shows remarkable differences with the Rcode, repetition of the design modification is needed for those approximate to the Rcode. Application of the proposed design procedure to 2-D steel braced RC buildings has proven to be efficient.