Analytical study on seismic performance of ECC shell-RC column and its plastic hinge forming mechanism

Engineered cementitious composites (ECCs) are a type of high-ductility material with excellent crack-control capacity and pseudo-strain-hardening behaviour. To improve the seismic performance and damage-tolerant capacity of traditional reinforced concrete (RC) columns, this paper proposes an innovative ECC-RC composite column with a cast-in-place or precast ECC shell in the plastic-hinge zone, namely the ECC shell-RC column. Based on finite element software ABAQUS, a comprehensive numerical and analytical study of the seismic performance of the ECC shell-RC column was conducted. First, three-dimensional (3D) nonlinear finite element models were developed and validated using previous experimental results. Subsequently, the influence of different design parameters on the seismic performance of this type of column was systematically investigated via finite element analysis, including the ECC height, ECC shell thickness, axial compression ratio, and material parameters. The seismic performance of the ECC shell-RC column with optimized design parameters subjected to actual ground motions was also preliminarily investigated. Notably, certain important design principles of ECC shell-RC columns were established. Furthermore, the theoretical critical height and thickness of the ECC shell were determined based on a theoretical analysis of the plastic-hinge (PH) forming mechanism.