Proposal of a fatigue life prediction method for RC slabs failed under traveling wheel-type load test

Abstract

Reinforced concrete (RC) bridge deck slabs are major components of a bridge superstructure, and RC slabs are usually damaged under fatigue loading and fail in shear. In order to solve this problem, many researchers performed numerous experiments and investigations over past decades. These efforts indicate that punching shear failure mode observed in real bridges can be simulated by a traveling wheeltype load test. To date, researchers developed several fatigue life prediction methods and proposed failure mechanisms based on the experimental results performed in past studies. However, experimental results indicate different trends, because the fatigue life of RC slabs is affected by various factors. Therefore, there is a need for a rational fatigue life prediction method that can inclusively evaluate all experimental results from past studies. It is important to note that a prediction method based on damage and failure mechanism under fatigue loading has not been developed to date. In the present study, a fatigue life prediction method that was developed based on the existing experimental data of fatigue life of RC slabs is proposed by modifying the JSCE shear design equation for a linear member. In the method, reinforcement ratios of both main and distributing bars and the proportion between main and distributing bars are considered as major parameters because slabs are modeled as beam-formed elements when traveling load is applied. In the study, the sensitivity of reinforcement ratios toward fatigue life in each method is compared: the proposed method, 3D Finite Element (FE) analysis, and an existing equation by Matsui. The results indicate that the proposed equation estimates greater effects of the reinforcement when compared to the existing equation and FE analysis.