Structural Vulnerability Analysis Of Three-Tower Self-Anchored Suspension Bridge Based On Reliability Theory

The self-anchored suspension bridge has a beautiful shape and outstanding landscape effect,and has been widely used in urban bridges in recent years.There are many evaluations on its seismic performance,and the results are mostly concentrated on the analysis of fixed value,while the research on seismic risk assessment by using probabilistic methods is rare.In this paper,a three-tower self-anchored suspension bridge is taken as an engineering example.The finite element software is used to analyze the nonlinear time history of the bridge to the bridge and the transverse vibration of the bridge.The seismic vulnerability of the structure is taken as the research goal.the following research work was mainly carried out.Firstly,the research literature on seismic vulnerability of bridge structures is reviewed in detail.The development process of seismic vulnerability of bridge structures is reviewed.The methods for establishing different vulnerability curves are summarized.Secondly,the structural finite element dynamic model is established and analyzed.Based on the dynamic characteristics of the structure,the ground motion record is selected and the structural nonlinear time history analysis is carried out.Then,based on the target performance of the structural member,the damage index of each component of the structure under different damage levels is determined.Finally,the structural ground motion response is performed.Regression analysis was carried out to compare the vulnerability of components and systems of the fully floating structural system and the structural system after the installation of the damper device,and the corresponding structural vulnerability curves were drawn.The results of this study show that:(1)Under the action of along-bridge ground motion,the probability of each vulnerable member of the fully-floating system three-story self-anchored suspension bridge under different damage levels is positively correlated with the earthquake intensity,and the probability of component damage is from easy to difficult.Support,side pier,sling,side tower,middle tower.The damage surpassing probability of the full-floating structural system is higher than the damage surpassing probability of each component;the damping connection system is reduced compared with the damage surpassing probability of the corresponding component of the full-floating system,and the damage surpassing probability of the bearing member is reduced the most,the damper connection The damage probability of each component in the system is from edge to sling,sling,support,side tower and middle tower.The damage surpassing probability of the damping connection system is reduced compared with the full floating structure system.(2)Under the action of transverse-bridge to ground motion,the over-probability of each component of the fully-floating three-tower self-anchored suspension bridge under different damage levels is positively correlated with the ground motion intensity.The probability of damage of each component is from support to difficulty,and is the support,the side pier,the side tower and the middle tower.The damage probability of the fully floating structural system is obviously higher than the damage probability of each component;the damage surpassing probability of each component in the damper connection system is still positively correlated with the ground motion intensity,and the damage probability of the component is from the easy to the difficult as the support,the side pier,Side tower and middle tower.The damage probability of the damper connection system is reduced compared with the corresponding component of the full floating system.The damage overrun probability of the damper connection system is significantly lower than that of the full floating system,and the reduction amplitude increases with the increase of the ground motion intensity.Based on the above vulnerability analysis results,the support and the side pier should be set as the key inspection components after the earthquake.