Seismic behaviour of seawater coral aggregate concrete columns reinforced with epoxy-coated bars

Abstract

This study investigates the seismic behaviour of seawater coral aggregate concrete (SCAC) columns reinforced with epoxy-coated bars (ECBs). The structural response and seismic damage of the columns were systematically evaluated using low-frequency cyclic lateral loading. A total of six columns, considering four different parameters—the type of concrete (SCAC and ordinary concrete (OC)), longitudinal reinforcement ratio (1.13% and 2.01%), stirrup ratio (0.50% and 0.72%), and axial load ratio (0.1, 0.2, and 0.3)—were fabricated. The failure pattern, bearing capacity, ductility, and hysteretic energy of the ECB-reinforced SCAC columns (SCACC–ECB) were analysed. The results indicate that the seismic behaviour of SCACC–ECB was acceptable, and the failure pattern of the columns changed with the type of concrete used. SCAC significantly reduced the ductility of the columns; however, its effects on the bearing capacity and hysteretic energy were negligible. On average, the SCAC columns had a 20% lower ductility and a 6.7% lower bearing capacity than the OC columns under similar conditions. Increasing the longitudinal reinforcement ratio and stirrup ratio increased the ductility and hysteretic energy of SCACC–ECB, while its stiffness decreased with the increase in the axial load ratio. The results indicate that the effects of the various factors on the seismic behaviour of SCACC–ECB in increasing order are concrete type, stirrup ratio, longitudinal reinforcement ratio, and axial load ratio. Finally, the characteristic load and displacement of SCACC–ECB were derived, and a general seismic damage assessment method considering the effects of SCAC and ECBs was proposed, which can be used to conduct an analytical evaluation of the structural response and seismic damage of marine structures.