Seismic performance and damage assessment of epoxy-coated steel bar-reinforced seawater coral concrete columns

A total of six columns were fabricated and tested under low-cycle reversed loading to study the seismic performance of seawater coral concrete (SCC) columns, covering four different parameters, namely, the type of concrete, longitudinal reinforcement ratio, stirrup ratio, and axial load ratio. The failure pattern, bearing capacity, ductility and hysteretic energy of SSC columns reinforced with epoxy-coated bars (ECBs) were analysed. The test results indicate that the seismic performance of ECB-reinforced SCC columns (ECB-SCCC) is favorable. The use of SCC leads to significant changes in the ductility and stiffness degradation of the columns. However, its effects on the bearing capacity and hysteretic behavior are negligible. Compared to ordinary concrete columns, the displacement ductility coefficient and bearing capacity of SCC columns are reduced by 19.25% and 6.67%, respectively, while the yield load and peak displacement are increased by 5.94% and 25.90%, respectively. It is found that the hysteretic characteristics of ECB-SCCC change significantly with the variations of longitudinal reinforcement ratio and axial load ratio. Increasing the stirrup ratio could enhance the ductility of specimens. Finally, the skeleton curve model of ECB-SCCC was derived, and the seismic damage assessment method was proposed. When the lateral displacement reaches the ultimate elasto-plastic inter-layer displacement angle, the longitudinal reinforcement ratio and the stirrup ratio are suggested to increase by 10% and 16%, respectively, so that the damage degree of the SCC column is similar to that of the ordinary concrete column. © 2022, Editorial Office of Journal of Building Structures. All right reserved.