Numerical modelling of engineered cementitious composites-concrete encased steel composite columns

Abstract

Recently, a new section form of concrete encased steel composite columns with Engineered Cementitious Composites (ECC) confinement (ECC-CES), which outperforms conventional CES columns in terms of failure behaviour, ductility and toughness has been introduced. Numerical modelling of the post-peak behaviours of such encased composite columns is a challenging task due to brittle failure of concrete, interface bond failure and buckling of steel section. This study presents a finite element modelling procedure for the ECC-CES columns. Both material and geometric nonlinearities are incorporated in the model and inelastic behaviour of ECC, concrete and steel were described by using appropriate material constitutive laws. Moreover, effects of initial geometric imperfections, contact interactions and confinement by steel and ECC encasement on concrete core were considered. Concrete damaged plasticity model was employed to describe the failure of ECC and concrete. The FE model was validated against experimental results and found to give good predictions of compressive behaviour of ECC-CES columns compared with the test results. Finally, a small scale parametric study was conducted using the validated numerical model to study the effect of the materials' strength on the column compressive behaviour.