Damage-induced Cable Broken Of Bridge Structure And Its System Reliability Analysis

Cable and other cable components are important to arch bri dges and cable-stayed bridges,while they are susceptible to corrosion damage and occational limit load,leading to rupture and threatening the service safety of the whole structure.To understand the service condition of the structure of the bridge effect ively,the damage of cable components and whole effect on the structure after fracture need to be studied in a system way.This paper researched the corrosion status of service suspender of concrete-filled steel tube arch bridge,whole bridge dynamic respo nse and system reliability of cable-stayed bridges caused by occational limit load.(1)Based on a project of suspender replacement of a steel tube concrete arch bridge,corrosion damage of inner steel wires was analised by experiments on replaced suspenders,average corrosion degree and pitting corrosion degree and corresponding probability distribution were obtained;And the stress-strain relationship of corrosion of steel wire was determined through the experiment,relationship between load and strain of suspender was studied by research on effect of corrosion on steel wire relationship which revealed the effect of corrosion on the bearing limit capacity of the suspender.(2)A cable-stayed bridge in cantilever state was built by using ANSYS finite element software,and nonlinear dynamic analysis of the seccessive breaking off due to fire was processed to the study the limit bearing situation on various breakage paths.Besides,parameter analysis of breakage caused by various fire spots and different ignition time of adjacent cable was processed to study the dynamic response on key components and cross sections,which drew the conclusion that fracture of outer cable is more dangerous than that of inner cable of a cantilever state cable-stayed bridge and influence of cable fracture on main tower is greater than that of main girder.(3)Stage critical strength branch-boundary method is used to study the system reliability of a cable-stayed bridge under outside load,the main failure mode was searched,failure model and system reliable index as well as the correlation coefficient matrix were calculated,the approximate linear correlation between system failure modes were discoveried;At the same time,this paper analyzed effect of the cable resistance attenuation on structural system reliability and result showed that cable resistance attenuation have little impact on cable-stayed bridge structure failure modes;Finally studied system reliability of cable-stayed bridge in different cable fracture conditions,the results showed that the remaining structural system reliability indices decreased remarkably in the case of the breakage of the outside cable...