A comprehensive study on the effects of chloride corrosion on hysteretic behaviors of thin-walled cast-in-place and precast hollow piers

Precast piers have been widely adopted worldwide due to their advantages in rapid construction, high quality, and minimal disruption to traffic and the environment. Building upon this concept, precast thin-walled hollow piers offer additional benefits, including further reductions in self-weight and construction costs. Nevertheless, corrosion remains a critical factor affecting the service life of bridge piers. However, current research on precast piers (particularly hollow precast piers) remains limited, especially concerning their durability under corrosive conditions. To study the difference of seismic behaviors between cast-in-place (CIP) and precast thin-walled hollow piers (PTP) under varying corrosion ratios, a total of five piers were tested cyclically after the accelerated corrosion. Although high-strength mortar was poured to connect the precast pier shaft and footing, the detection suggested that the corrosion ratio of rebars within the interface region was nearly 1.9 times that of the rebars within the shaft. Furthermore, the stirrups were corroded much faster than the flexural counterparts, which resulted in rapid loss of strength and ductility of core concrete, and the occurrence of inelastic compressive buckling of flexural rebars. It was found that seismic-resistant capacity of PTP piers degraded faster than that of CIP counterparts when subject to moderate or high corrosion ratios. Based on experimental observations, modeling strategies were developed for corroded piers, incorporating bond-slip behavior, corrosion level assessments for flexural and shear reinforcement, and the mechanical properties of both cover and core concrete as well as corroded rebars. Inelastic compressive buckling of flexural rebars was found to play a critical role in the pinching behaviour of corroded piers. A hysteretic model within the OpenSees platform was adopted and calibrated accordingly. Finally, sensitivity analyses of key parameters were conducted to investigate their influence on the seismic performance of corroded piers.