Seismic behavior of novel resilient and corrosion-resistant composite columns using strain-hardening engineered cementitious composites and steel-FRP composite bars

Abstract

This paper proposed a novel composite column with exceptional resilience and corrosion resistance achieved through the casting of engineered cementitious composites (ECCs) in the plastic hinge region and the utilization of steel-FRP composite bars (SFCBs). A total of six specimens were tested under constant axial load and cyclic lateral load to examine their seismic performance and reparability. The influence of the type of longitudinal reinforcement (steel bar, SFCB, and GFRP bar) and the matrix type (ECC and concrete) in the plastic hinge region was discussed. Test results indicated that configuring SFCB in the columns facilitated drift-hardening characteristics, which in turn enhanced resilience. The adoption of ECC in the plastic hinge region further reduced residual deformation of the composite columns while significantly improving both lateral strength and ductility. The maximum repairable limit of the specimens increases by a factor of 1.36, 1.86, and 2.5, respectively, as the FRP content increases from 0% to 31.3%, 56.4%, and 100%. The specimens reinforced with SFCBs can be quickly restored to their intended use without repair, before reaching a 2% drift ratio. The slip effect of SFCBs has a substantial impact on increasing the lateral displacement of test columns, and this effect tends to increase with an increase in FRP content. A fiber model was developed for predicting the skeleton curves, and its accuracy was validated through comparisons between the predicted and test results.