Fatigue Damage Research And Safety Design Analysis Of Suspender Of Half-through Arch Bridge

Since the reform and opening up in the 21 st century,economic construction in various parts of China has grown tremendously.Along with the tremendous development of the domestic transportation industry,the overweight and overloading of traffic in many areas has become increasingly serious.As a key link in the transportation industry,the bridge bears the traffic volume far beyond the original design,which makes the structural fatigue damage caused by the cyclic load of the vehicle become the biggest hidden danger affecting the safety of the bridge.The half-through arch bridge has become a long-lasting structural form in the history of bridge construction because of its large spanning capacity,good carrying capacity and beautiful appearance.The boom is an important forcetransmitting component of the bridge system and the arch rib,and its health affects the entire bridge.Therefore,whether in-service arch bridge can meet the increasing traffic flow,how much impact the overweight vehicle will have on the fatigue performance of the boom components is a problem worth studying.This paper aims to establish a fatigue vehicle model that meets the local traffic volume in different regions by studying the method of fatigue load spectrum.Combined with a practical half-through arch bridge,a finite element model is established to analyze the fatigue performance of the boom member under vehicle load.Finally,the safety design analysis of the bridge is carried out by establishing the structural form of the asymmetric double boom.The main research contents are as follows:(1)This paper introduces the fatigue failure characteristics of suspenders of half-through arch bridges,and analyses the causes of the failure based on the fatigue cumulative damage theory.(2)By introducing the compilation methods of vehicle load spectrum in BS5400 code,AASHTO code and European code.Based on the existing traffic statistics technology in China,dynamic weighing system(WIM),a set of process for establishing fatigue load spectrum is proposed,which provides a fatigue vehicle model for the fatigue study of suspenders.(3)Based on the data of multi-period traffic flow collected by WIM system of a certain section in Guangdong Province and the compilation logic of fatigue load vehicle model in foreign codes,a vehicle load spectrum which can be used for fatigue assessment of local suspender members is proposed.(4)A through arch bridge in Guangdong Province was built by using finite element software MIDAS/CIVIL to simulate the fatigue performance of suspender members under vehicle loads.The fatigue life is calculated and evaluated.(5)The failure modes of suspenders under asymmetric parallel double suspenders are analyzed.Discussing the feasibility of applying "damage-safety" design theory to suspender design of arch bridge.