Reducing target reliability index of concrete bridge beams through compression yielding

Abstract

Damage to reinforced concrete (RC) bridges due to accidental overloading is inevitable, especially for those that deteriorate over time due to various environmental and operational factors. When significant damage occurs, it needs to be replaced. However, replacing bridges is expensive and time-consuming. This problem can be well resolved by the concept of compression yield (CY) structures. When an overload occurs, the CY block in the beam is triggered like a fuse, forcing the beam to deform in a ductile manner, thus preventing further overloads. Additionally, the damaged CY blocks can be replaced without replacing the entire beam. Due to this safer failure mode and lower cost of failure, the safety reserve of the CY beam can be significantly lower than that of the traditional RC structure, which means that the target reliability of the CY bridge needs to be re-established. The objective of this study is to develop the target reliability of CY bridge. The target reliability of structures is determined through cost optimization. The life-cycle costs for bridges are determined based on the practical construction and post-construction management process. The calculated results indicate that although the initial cost of CY beams could be higher, the losses associated with failures are significantly lower compared to RC beams. Consequently, the target reliability and life cycle costs of CY bridge can be lower than those of the RC bridge.