Fatigue damage evaluation of steel-concrete composite beam of long-span suspension bridge considering vehicle-bridge coupled effect

In order to study fatigue life of steel-concrete composite beam of long-span suspension bridge under different fatigue vehicle loads and its fatigue cumulative variation laws within its operation period considering vehicle-bridge coupled effect, a suspension bridge with main span of 720 m was taken as an example to perform detailed analysis. Firstly, based on static analysis of a local beam segment finite element model, fatigue detail concern points were determined to obtain the corresponding stress concentration coefficients. Then, the fatigue damage degree and fatigue life under action of fatigue load model III, AASHTO code standard fatigue vehicle and Hebei Province fatigue load spectrum were evaluated by using P-M and CDM evaluation models. Finally, considering the vehicle-bridge coupled dynamic effect, influences of vehicle load, vehicle speed, deck pavement deterioration and future traffic growth on fatigue damage accumulation within the structure's operation period were analyzed. The results showed that the most disadvantageous section of this kind of steel-concrete composite girder suspension bridge is at the place of 1 / 8 span, and the node being easy to have fatigue failure is the joint between main beam roof plate and web near the suspension point; fatigue damage amount under action of fatigue load model III is close to that under action of the local fatigue load spectrum, fatigue damage cumulative amount under action of AASHTO fatigue vehicle is obviously lower than those under action of the other two types; the relation between cumulative damage change trend of fatigue detail concern points at different positions and fatigue speed is not clear; increase in vehicle load, traffic amount and deterioration of bridge deck pavement accelerate growth of fatigue damage accumulation. © 2021, Editorial Office of Journal of Vibration and Shock. All right reserved.