Experiment And Research About Fatigue Property Of Steel Bridge Integral Joint

Integral joint is a new-type structure that has been already adopted in the long span steel truss bridge in the last few years. Integral joints are assembled with thick steel plate by welding. Not only are welding seams dense, but also the types of welding seams are various in the integral joint. There are a lot of factors which affect structural fatigue strength. The fatigue resistance of complicated welded structure subjected to moving vehicle loads needs to be further researched . Taking the fatigue test for connecting reliability of track cross beam and integral joint of Chongqing Caiyuanba Yangtze double-deck Bridge as an instantce, the test load and the fatigue reliability of the integral joint details are studied in this thesis. The main contents are in the followings.First of all, some basic conceptions of steel bridge fatigue are introduced.The main factors causing steel bridge fatigue are analyzed.The advantages and disadvantages of the fatigue damage cumulative rules are discussed.Secondly, fatigue load spectrums of highway and railway are studied, and the presently domestic and international research state to fatigue load spectrum of steel bridge is briefly introduced. The thesis introduces the fatigue load spectrum of British Standards Institution BS5400 and AASHTO bridge design standards, then compares and analyzes the fatigue design methods of the two design standards.At last, the thesis emphatically studies the fatigue load spectrum of double-deck bridge, and provides the fatigue load spectrum of bridges that bear straddle type monorail loads. Based on this, the thesis concludes the fatigue test load of Chongqing Caiyuanba Bridge, and fatigue test model is designed.By using a three dimensional FEM model of the fatigue test model, the factors of stress concentrateion of critical regions are obtained, and the test method is provided.