Fatigue life of RC bridge decks affected by speed and load weight of wheel-type moving loads

Abstract

Over the service life of a bridge, vehicles vary in terms of speed and load weight, leading to varying degrees of fatigue damage. Particularly under wet condition, the fatigue life of reinforced concrete (RC) bridge decks experiences a significant decline. In this study, the results of fatigue life of RC bridge decks are systematically calculated for under wheel-type moving loads with various speed and load weight according to practical situation of bridges in both dry and wet condition by an acceptable approach involves a multi-scale and multi-chemo–physics analysis system (DuCOM-COM3) that incorporates the water-crack interaction. The results indicate that the effect of speed on fatigue life is not significant and follows a complex pattern, and the effect of load weight on fatigue life is dominant, with a heightened sensitivity to load weight variations under wet condition. Based on the simulation results of fatigue life, calculation formulations for fatigue life are presented accurately for dry and wet condition respectively, considering both load weight and speed as parameters, with the determination coefficients R2 are 0.977 and 0.952, respectively. In addition, a predictive method for the service life under constant environmental condition is proposed based on the Palmgren-Miner’s linear rule, and a case analysis is conducted by utilizing practical traffic flow data monitored by a piezoelectric-based dynamic weigh-in-motion system set on Jiashao Bridge, showing that the service life under dry condition is 55.41 years, while that under wet condition reduces to 1.03 years. Finally, a comprehensive service life predictive method considering actual and alternating environmental conditions is proposed.