Study On The Time-dependent Reliability Of Arch Bridge Suspender System Under Multiple Factors

Suspender is a very important tension component in through arch bridge,which plays a role in connecting arch rib and bridge deck structure.The failure of suspender will have a serious impact on the safety of the whole arch bridge structure,so this kind of arch bridge needs to pay special attention to the safety and reliability of suspender.At present,most of the related researches mainly analyze the time-dependent reliability of the suspender system under corrosion and vehicle load,while there are few researches on the time-dependent reliability of the suspender system considering other load types,especially from the perspective of the decrease of the suspender bearing capacity caused by the bending phenomenon of the suspender caused by temperature load.Therefore,this paper combines corrosion,vehicle load and temperature load to study the time-dependent reliability of suspender system in detail,excavates the internal law of temperature load,and summarizes the influence of these three factors on the time-dependent reliability of suspender system.The main work of this paper is as follows:(1)The damage causes of suspenders are analyzed and discussed,and the main factors affecting the service life of suspenders are determined.Based on the S-N curve of suspender,the fatigue performance of suspender is analyzed.The S-N curve of 1860 MPa steel strand suspender considering corrosion or not is obtained,and the S-N curve of suspender under different deflection angles is deduced.(2)Based on the statistical law of vehicle load,the solution of the distribution law of stress amplitude and stress amplitude cycle times ignoring the influence of vehicles is determined.This paper discusses that it is more reasonable to use the daily average temperature as the effective temperature for concrete structure or steel-concrete structure.By using the statistical data of a weather station,it is proved that the normal distribution of the daily average temperature in each season fits well.(3)Based on the cumulative damage rule,reliability theory and system reliability theory,the time-dependent reliability related function of the suspender system is obtained.Further considering the effect of temperature load,the equation is modified,and the universal temperature modified time-dependent reliability equation is obtained.(4)Based on the example model of Pingnan No.3 Bridge,the time-dependent reliability of suspender system under different failure modes is calculated and compared.By analyzing the temperature distribution of the bridge site,it is proved that the influence of temperature load on the fatigue life of suspenders can not be ignored.Through the time-dependent reliability analysis of the suspender,it is found that the service life of the short suspender considering the temperature load decreases by 5.13%,and the other suspenders can ignore this effect.At the same time,it is found that the most dangerous suspender is changed from the second short suspender to the short suspender after considering the temperature load.Therefore,when analyzing the most dangerous suspender of arch bridge,it is necessary to consider the influence of temperature load.