Study on Fatigue Stress of Structural Details of Improved Composite Box Girder Bridge with Corrugated Steel Webs
The key components of steel bridges under vehicle loading are subjected to cyclic loading,causing fatigue;the continuous accumulation of fatigue may lead to fatigue damage or even fracture of the components.The fatigue impact coefficient is an important parameter for evaluating the influence of vehicle load on the fatigue performance of bridges.With an increase in the operating life of a bridge,the bridge deck roughness deteriorates,affecting the fatigue impact coefficient of the bridge.An improved composite box girder bridge with corrugated steel webs(ICBGBCSW)is a new type of bridge structure.However,the forces acting on its structural details are complex,making it crucial to study the fatigue performance of the ICBGBCSW structural details.Therefore,this study investigated the fatigue stress of the ICBGBCSW structural details,considering the deterioration of the bridge deck roughness.First,finite element software was used to calculate the static stress of the ICBGBCSW under the action of a static load to determine the fatigue stress distribution of the structural details of the ICBGBCSW.Subsequently,the effects of different vehicle speeds and bridge deck roughness levels on the fatigue stress and fatigue stress impact coefficients of the ICBGBCSW structural details were investigated.Finally,based on the bridge deck roughness degradation model,the design value of the fatigue impact coefficient of the ICBGBCSW was proposed.The results show that the stress easily concentrates at the corrugated folds of corrugated steel webs(CSW).When the bridge deck unevenness deteriorates to poor or very poor,its stress and stress amplitude impact coefficients exceed 0.15,as specified in the AASHTO Bridge Code.The stress and stress amplitude impact coefficients exceeded the values in the AASHTO Bridge Code when the bridge deck roughness is average and the vehicle speed is less than 60 km·h-1.The research results can provide a reference for analyzing the fatigue stress and fatigue impact factor of ICBGBCSW,considering the deterioration of the bridge deck roughness.
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