Research About Fatigue Property Of The Connections Of Track Cross Beam And Integral Joint In Long-Span Combined Bridge

Along with the increasing of steel bridge's span and the development of weldingtechnology, a new-type structure——integral joint has been regular adopted in thelast few years. Not only are welding seams dense, but also the types of welding seams are various in the integral joint. The fatigue resistance of complicated welded structure subjected to moving vehicle loads needs to be further researched. To the long span steel truss bridge, joint fatigue damage is the main-type destroy. In this thesis, the study method combining theory calculation with model test is adopted. Based on Chongqing Caiyuanba Yangtze Bridge, the fatigue reliability of the connecting of track cross beam and integral joint is studied.First of all, some basic conceptions of steel bridge fatigue are introduced, and some basic theories about fatigue strength are also introduced in this thesis. The main factors causing steel bridge fatigue and the fatigue damage cumulative rules are analyzed.Secondly, on the basis of introducing the fatigue strength of welding joint, the main factors causing welded structure fatigue are analyzed and the methods for improving structure 's fatigue strength are introduced. Than the structure details contained in integral joint are analyzed, and the fatigue property of steel bridge integral joint is evaluated.At last, benefit from the research results of home and abroad, the structure fatigue property is analyzed by the model fatigue test. Based on these, stress of it is calculated by the finite element software. According to comparing an analyzing the test results and theory results, it is proved that the connections of integral joint and track cross beam of Chongqing Caiyuanba Yangtze Bridge is reliable.