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A simplified fragility analysis of f

时间:2021-12-10 17:32:52 天文地理论文 我要投稿

A simplified fragility analysis of fan type cable stayed bridges

A simplified fragility analysis of fan type cable stayed bridges using Probabilistic Risk Analysis (PRA)procedure is presented for determining their failure probability under random ground motion. Seismic input to the bridge support is considered to be a risk consistent response spectrum which is obtained from a separate analysis. For the response analysis, the bridge deck is modeled as a beam supported on springs at different points. The stiffnesses of the springs are determined by a separate 2D static analysis of cable-tower-deck system. The analysis provides a coupled stiffness matrix for the spring system. A continuum method of analysis using dynamic stiffness is used to determine the dynamic properties of the bridges .The response of the bridge deck is obtained by the response spectrum method of analysis as applied to multidegree of freedom system which duly takes into account the quasi - static component of bridge deck vibration. The fragility analysis includes uncertainties arising due to the variation in ground motion, material property, modeling, method of analysis,ductility factor and damage concentration effect. Probability of failure of the bridge deck is determined by the First Order Second Moment (FOSM) method of reliability. A three span double plane symmetrical fan type cable stayed bridge of total span 689 m, is used as an illustrative example. The fragility curves for the bridge deck failure are obtained under a number of parametric variations. Some of the important conclusions of the study indicate that (i) not only vertical component but also the horizontal component of ground motion has considerable effect on the probability of failure; (ii) ground motion with no time lag between support excitations provides a smaller probability of failure as compared to ground motion with very large time lag between support excitation; and (iii) probability of failure may considerably increase for soft soil condition.

作 者: R. A. Khan T.K.Datta S. Ahmad   作者单位: R. A. Khan(Civil Engineering Department, Jamia Millia Islamia, New Delhi-25, India)

T.K.Datta(Civil Engineering Department, Indian Institute of Technology, New Delhi-16, India)

S. Ahmad(Department of Applied Mechanics, Indian Institute of Technology, New Delhi-16, India) 

刊 名: 地震工程与工程振动(英文版)  SCI 英文刊名: EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION  年,卷(期): 2005 4(1)  分类号: P315  关键词: probabilistic risk analysis   fan type cable stayed bridge   fragility analysis   first order second moment