Detailed Analysis Of The Fatigue Details Of The Highway Steel Bridge Webs

With the rapid development of the steel industry,the number of steel bridges has increased sharply in recent years.In China in recent years a large number of new steel bridge built and put into use,although the bridge strength is very strong,but the classification of fatigue details of the bridge codes in our country related is still not precise enough,a lot of new structural form is still not fatigue calculation model of concrete,the lack of experimental data support,so it is of great importance to all the details in steel bridge fatigue research.Steel bridge fatigue is mainly divided into two kinds of surface deformation fatigue,fatigue load causes simple in anti fatigue design only to bridge internal force analysis,the fatigue of domestic and foreign research field now data is rich,has a mature system of fatigue design;The fatigue failure caused by out of plane deformation is related to the fatigue details of different structures.It is necessary to study the exact fatigue stress of each part of the steel bridge to classify it,so we need a lot of research data as a basis.Due to the large tension caused by flange transverse cracks,the transverse connecting plate and flange have a small gap region,this paper studies the web plane fatigue is located in steel bridge girder web and lateral connection board at the end of the small gap location in the area of the surface deformation in the the practical design of steel bridge,can not be completely avoided,resulting in fatigue crack and the girder web,directly affect the mechanical performance of steel bridge.This paper first carries on the description to the out of plane steel web fatigue details analysis of small gap region bear the role of random vehicle load.In practice,the stress and the fatigue crack extension to form,and then introduces the research of load spectrum and stress spectrum,rain flow counting method,the fatigue strength and fatigue curve cumulative damage rule theory.After summarizing the relevant fatigue load vehicle models at home and abroad,a simplified standard fatigue vehicle model with equivalent damage is developed based on the fatigue damage accumulation criterion according to the characteristics of vehicle loads in Southwest China.In the web of steel out of plane fatigue details were optimized and analyzed,using the large finite element software ANSYS was used to simulate a small bridge,discusses the effect of setting,web connection and stiffening rib beam at the set chamfer,the lower flange of the main girder and stiffener welding,web depth,web thickness,height,small clearance stiffener thickness,rib width of the detail structures on the web gap out of plane deformation fatigue performance.Finally,the optimization measures before analysis are managed together,and the small and steel bridge models optimized before and after optimization are calculated through actual examples.The obtained results show that the overall optimization effect can reach 68.04%,and all meet the requirements of anti fatigue checking.