Field investigation and numerical analysis of horizontal cracking in ledge girders of post-tension concrete bridges

Abstract

This research addresses the pressing issue of horizontal crack initiation in ledge girders of post-tensioned concrete (PTC) bridges, which is a significant concern for the safety and longevity of long-span bridges. With field observations and advanced engineering computations, the study identifies the primary causes of these cracks and explores potential mitigation strategies. The research pinpoints the primary causes of horizontal crack initiation in PTC girders by analyzing 3D finite element modeling and comparing the results with the analytical solution suggested by a design code. The study also probes the potential of using external prestressing with a post-tensioning bar to mitigate horizontal cracking. The findings underscore the significance of adhering to the design code requirements for hanger reinforcement, which notably mitigates crack width in PTC girders. The research also highlights that higher prestress losses correspond to increased crack width, emphasizing the need to consider prestress losses for maintaining structural resilience. Furthermore, the study reveals that in all strengthening cases, the maximum crack width is notably reduced at the point of failure, albeit less effectively than when using rebar as per the design code. These findings underscore the potential of post-tensioning as a strengthening technique and the importance of adhering to design standards.