Fatigue Analysis of RC Slabs and Repaired RC Slabs Based on Crack Bridging Degradation Concept

Fatigue of reinforced concrete (RC) bridge slabs is analyzed based on crack bridging degradation concept. RC slabs are typically subjected to a large number of load repetitions due to traffic, and their failure processes are characterized by progressive concrete cracking. This study applies the recently developed fatigue analysis method based on crack bridging degradation to slab problems. The bridging stress degradation of concrete cracks is introduced as a primary mechanism for the propagations of cracks that induce failure. A three-dimensional finite element method, which consists of smeared crack elements for concrete and rod element as reinforcing bars, is proposed. The fatigue life and its failure patterns are focused on. The analysis of RC slabs under different loading conditions demonstrates that the slab under moving load exhibits shorter fatigue life and more severe damage than that under fixed pulsating load. The extension of fatigue life due to underlay and overlay repairs is evaluated numerically. All repaired slabs exhibit a large extension of fatigue life and a reduction of midspan deflection when compared with the original slab.