Evaluation of seismic collapse capacity of regular RC frames using nonlinear static procedure

Maysam Jalilkhani,Ali Reza Manafpour 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.6

The Incremental Dynamic Analysis (IDA) procedure is currently known as a robust tool for estimation of seismic collapse capacity. However, the procedure is time-consuming and requires significant computational efforts. Recently some simplified methods have been developed for rapid estimation of seismic collapse capacity using pushover analysis. However, a comparative review and assessment of these methods is necessary to point out their relative advantages and shortcomings, and to pave the way for their practical use. In this paper, four simplified pushover analysis-based methods are selected and applied on four regular RC intermediate moment-resisting frames with 3, 6, 9 and 12 stories. The accuracy and performance of the different simplified methods in estimating the median seismic collapse capacity are evaluated through comparisons with the results obtained from IDAs. The results show that reliable estimations of the summarized 50% fractile IDA curve are produced using SPO2IDA and MPA-based IDA methods; however, the accuracy of the results for 16% and 84% fractiles is relatively low. The method proposed by Shafei et al. appears to be the most simple and straightforward method which gives rise to good estimates of the median sidesway collapse capacity with minimum computational efforts.

Development of a nonlinear seismic response capacity spectrum method for intake towers of dams

Leonardo Cocco,Luis E. Suárez,Enrique E. Matheu 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.36 No.3

The seismic-induced failure of a dam could have catastrophic consequences associated with the sudden release of the impounded reservoir. Depending on the severity of the seismic hazard, the characteristics and size of the dam-reservoir system, preventing such a failure scenario could be a problem of critical importance. In many cases, the release of water is controlled through a reinforced-concrete intake tower. This paper describes the application of a static nonlinear procedure known as the Capacity Spectrum Method (CSM) to evaluate the structural integrity of intake towers subject to seismic ground motion. Three variants of the CSM are considered: a multimodal pushover scheme, which uses the idea proposed by Chopra and Goel (2002); an adaptive pushover variant, in which the change in the stiffness of the structure is considered; and a combination of both approaches. The effects caused by the water surrounding the intake tower, as well as any water contained inside the hollow structure, are accounted for by added hydrodynamic masses. A typical structure is used as a case study, and the accuracy of the CSM analyses is assessed with time history analyses performed using commercial and structural analysis programs developed in Matlab.

Development of a nonlinear seismic response capacity spectrum method for intake towers of dams

Cocco, Leonardo,Suarez, Luis E.,Matheu, Enrique E. Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.36 No.3

The seismic-induced failure of a dam could have catastrophic consequences associated with the sudden release of the impounded reservoir. Depending on the severity of the seismic hazard, the characteristics and size of the dam-reservoir system, preventing such a failure scenario could be a problem of critical importance. In many cases, the release of water is controlled through a reinforced-concrete intake tower. This paper describes the application of a static nonlinear procedure known as the Capacity Spectrum Method (CSM) to evaluate the structural integrity of intake towers subject to seismic ground motion. Three variants of the CSM are considered: a multimodal pushover scheme, which uses the idea proposed by Chopra and Goel (2002); an adaptive pushover variant, in which the change in the stiffness of the structure is considered; and a combination of both approaches. The effects caused by the water surrounding the intake tower, as well as any water contained inside the hollow structure, are accounted for by added hydrodynamic masses. A typical structure is used as a case study, and the accuracy of the CSM analyses is assessed with time history analyses performed using commercial and structural analysis programs developed in Matlab.

Seismic assessment and retrofitting of existing structure based on nonlinear static analysis

Ni, Pengpeng Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.5

Seismic assessment and retrofitting of existing structure is a complicated work that typically requires more sophisticated analyses than performing a new design. Before the implementation of a Code for seismic design of buildings (GBJ 11-89), not enough attention has been paid on seismic performance of structures and a great part of the existing reinforced concrete structures built in China have been poorly designed according to the new version of the same code (GB 50011-2010). This paper presents a case study of seismic assessment of a non-seismically designed reinforced concrete building in China. The structural responses are evaluated using the nonlinear static procedure (the so-called pushover analysis), which requires its introduction within a process that allows the estimation of the demand, against which the capacity is then compared with. The capacity of all structural members can be determined following the design code. Based on the structural performance, suitable retrofitting strategies are selected and implemented to the existing system. The retrofitted structure is analyzed again to check the effectiveness of the rehabilitation. Different types of retrofitting strategy are discussed and classified according to their complexity and benefits. Finally, a proper intervention methodology is utilized to upgrade this typical low-rise non-ductile building.

Seismic assessment and retrofitting of existing structure based on nonlinear static analysis

Pengpeng Ni 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.5

Seismic assessment and retrofitting of existing structure is a complicated work that typicallyrequires more sophisticated analyses than performing a new design. Before the implementation of a Codefor seismic design of buildings (GBJ 11-89), not enough attention has been paid on seismic performance ofstructures and a great part of the existing reinforced concrete structures built in China have been poorlydesigned according to the new version of the same code (GB 50011-2010). This paper presents a case studyof seismic assessment of a non-seismically designed reinforced concrete building in China. The structuralresponses are evaluated using the nonlinear static procedure (the so-called pushover analysis), whichrequires its introduction within a process that allows the estimation of the demand, against which thecapacity is then compared with. The capacity of all structural members can be determined following thedesign code. Based on the structural performance, suitable retrofitting strategies are selected andimplemented to the existing system. The retrofitted structure is analyzed again to check the effectiveness ofthe rehabilitation. Different types of retrofitting strategy are discussed and classified according to theircomplexity and benefits. Finally, a proper intervention methodology is utilized to upgrade this typical lowrisenon-ductile building.

역량스펙트럼방법을 이용한 PSC 박스교의 지진취약도 해석

김광전,송종걸,Kim. Gwang Jeon,Song. Jong-Keol 한국방재학회 2014 한국방재학회논문집 Vol.14 No.4

대부분의 기존 지진취약도 해석은 응답이력해석을 이용하여 수행되어 오고 있다. 지반운동 동안에 많은 수의 구조부재를 가진 구조시스템에 대하여 비탄성 지진응답을 계산하는 데는 많은 시간이 소요된다. 지진취약도 해석은 많은 개수의 지반운동을 사용하여 평가함으로 많은 시간이 소요되는 과정을 포함한다. 보다 간단한 지진해석방법이 지진취약도 해석에 사용된다면 이와 같은 해석노력을 감소시킬 수 있다. 본 연구에서는 간단한 지진해석방법으로 역량스펙트럼방법을 PSC 박스거더교의 지진취약도를 평가하는데 사용하였다. 응답이력해석과 역량스펙트럼방법에 의한 지진취약도 곡선을 비교하여 평가하였다. Most of existing seismic fragility analysis have been performed using the response history analysis (RHS). It takes many times to calculate inelastic seismic response for a structural system with many structural members during a ground motion. Since seismic fragility analysis are evaluated using many ground motions, it is time consuming process. If the more simple seismic analysis method can be used to seismic fragility analysis, these analysis efforts can be reduced. In this study, the capacity spectrum method (CSM) as simple seismic analysis method is used to evaluate seismic fragility of PSC box-girder bridges. The seismic fragility curves calculated by using RHA and CSM are compared.

기존 화력발전소 터빈구조물의 비선형 내진성능평가

김갑순 ( Kim Kap-sun ),이경진 ( Lee Kyung-jin ),서용표 ( Suh Yong-pyo ) 한국구조물진단유지관리공학회 2002 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.6 No.2

Seismic capacity evaluation of Fossile power plant facilities must be carried out with appropriate evaluation scopes and methods according to guidelines and philosophies. But currently, there is no accurate seismic capacity evaluation provision of existing turbine generator structure in Fossil power plant. The purpose of this study is to evaluate accurate nonlinear seismic capacity of turbine generator structure. Seismic evaluation procedure is performed based on Capacity spectrum method(ATC-40). Nonlinear static analysis was performed and performance point for each seismic load level was computed. From the rusults, Although the turbine structure was designed for Z=0.075, it was sufficient to Z=0.15, 0.4’s earthquake demand.

2방향 중공슬래브 구조시스템의 비선형 지진거동 평가

박용구,김현수,고현 아이스트,박현재,이동근 한국지진공학회 2011 한국지진공학회논문집 Vol.15 No.1

최근 들어 슬래브 차음성능에 대한 관심이 커지고 있으며 이에 대응하여 슬래브 두께 증가가 요구되고 있다. 또한 건축물의 효율적인 공간 활용을 위하여 장스팬의 바닥판 시스템이 많이 사용되고 있다. 이러한 요구를 만족하기 위해 개발된 바닥판 시스템중의 하나가 2방향 중공슬래브이다. 2방향 중공슬래브의 구조적 성능을 확인하기 위해서는 지진이 발생하였을 때의 안전성에 대한 검토가 반드시 필요하다. 따라서 본 연구에서는 재료비선형 시간이력해석을 통하여 2방향 중공슬래브의 지진하중에 대한 거동을 평가하였다. 효율적인 시간이력해석을 위하여 기존에 제안된 등가플레이트 모델을 사용하였고, 또한 유효보폭법을 적용한 비선형 모델을 이용하여 2방향 중공슬래브를 적용한 예제구조물의 내진성능을 평가하였다. 이를 통하여 2방향 중공슬래브를 사용한 구조물이 동일한 슬래브 두께의 일반 플랫 플레이트 구조물에 비하여 내진성능이 저하되지 않음을 확인 할 수 있었다. Recently, there has been an increased interest in the noise isolation capacity of floor slabs, and thus an increase of slab thickness is required. In addition, long span floor systems are frequently used for efficient space use of building structures. In order to satisfy these requirements, a biaxial hollow slab system has been developed. To verify the structural capacity of a biaxial hollow slab system, safety verification against earthquake loads is essential. Therefore, the seismic behavior of a biaxial hollow slab system has been investigated using material nonlinear time history analyses. For efficient time history analyses, the equivalent plate element model previously proposed was used and the seismic capacity of the example structure having a biaxial hollow slab system has been evaluated using the nonlinear finite element model developed by the equivalent frame method. Based on analytical results, it has been shown that the seismic capacity of a biaxial hollow slab system is not worse than that of a flat plate slab system with the same thickness.

성능스펙트럼법을 이용한 기존 학교 건축물의 내진성능평가 및 보강효과 검증

장정현 ( Jeong Hyun Jang ),황지훈 ( Ji Hoon Hwang ),양경석 ( Kyeong Seok Yang ),( Kamiya Takashi ),최재혁 ( Jae Hyouk Choi ) 조선대학교 공학기술연구원 2012 공학기술논문지 Vol.5 No.1

Large scale earthquake was occurred in different parts of the world like Japan (in 1995), Republic of Pakistan (2005), in China (2008) etc and enormous structures were damaged. As a result of collapse of school buildings structures numerous students are died and it had a big impact on the international community. Therefore, the interest of preparing the seismic resistant school building structures in our country is increases as school building are used as emergency shelter for local residents. But the current standard of seismic design ratio of 3.7% is applied for school building in Korea which is only significant earthquake damage is expected. In order to overcome the current situation, seismic performance evaluation is carried out for the existing school building and an accurate and appropriate seismic retrofit is required based on performance evaluation to upgrade the existing school buildings. In this paper, nonlinear analysis on existing school buildings for ATC-40(Applied Technology Council, ATC) and FEMA-356(Federal Emergency Management Agency, FEMA) are carried out using the capacity spectrum method to evaluate seismic performance and to determine the need for retrofitting. In addition after reinforcement to enhance the seismic performance is applied the seismic perfor-mance evaluation is carried out to verify the effectiveness of seismic retrofit.

복합구조물의 하부골조층수 변화에 따른 비선형 약산법의 응답특성

김재웅,강병두,전대한,남영우 대한건축학회지회연합회 2005 대한건축학회지회연합회 학술발표대회논문집 Vol.1 No.1

One of the most accurate earthquake analysis method for the performance evaluation of structure is nonlinear time history analysis, but it is time-consuming and necessitate more efforts. Approximate methods are presented for estimating the capacity of structures while subjecting earthquake ground motions. This is made by exploiting the connection between the nonlinear static response of structure and the dynamic response of SDF system whose backbone matches the structure’s pushover curve. The capacity spectrum method is one of general approximate methods which is based on equivalent linearization where the inelastic deformation is approximated by the maximum deformation of an equivalent linear elastic system having equivalent viscous damping. It requires iterative computations, because the equivalent damping ratio is computed as a function of the maximum deformation. The nonlinear capacity spectrum method estimate the maximum inelastic deformation of SDF system by nonlinear response spectra. The nonlinear direct spectrum method is proposed and studied to evaluate nonlinear response of structures, without iterative computations, given by the structural linear vibration period and yield strength from the pushover analysis. In this study, it is to compare the accuracy and the reliability of approximate nonlinear methods with respect to upper wall-lower frame system and various earthquakes.