Experimental and numerical investigation on axial compression behaviour of prefabricated ECC shell–reinforced concrete column

To improve the mechanical behaviour of traditional reinforcement concrete (RC) column, a novel prefabricated engineered cementitious composite (ECC)–reinforced concrete composite (ECC shell–C) column was proposed in this study. Subsequently, five prefabricated ECC shell–C columns, as well as one cast–in–place (CIP) RC column and one CIP pure ECC column, were designed and manufactured. Then, axial compression tests were carried out to explore their mechanical behaviour with considering the effect of the ECC shell thickness t and stirrup ratio ρv. On this basis, a numerical analysis method for the composite column was developed and verified. And numerical parametric study was carried out to clarify the influence of the design parameters on the axial compression behaviour of the prefabricated ECC shell–RC columns, including the compressive strength of ECC (fc,ecc) and concrete (fc), as well as the longitudinal reinforcement ratio (ρs). The experimental and numerical results demonstrated that the ECC shell can improve cracking resistance, ductility capacity and energy dissipation capacity of the RC column. The accumulated energy dissipation and ductility coefficient of the prefabricated ECC shell–RC columns with different t was 2.13–2.46 times and 1.14–1.35 times greater than those of the RC column, respectively. The ρv had small influence on the bearing capacity of the prefabricated ECC shell–RC columns, which can be appropriately reduced in practical application. The numerical analysis method considering the confinement effect of ECC shell can provide reliable prediction for the axial compression behaviour of prefabricated ECC shell–RC columns. fc,ecc and fc have the positive influence on the bearing capacity of the prefabricated ECC shell–RC columns but have negative influence on the ductility; meanwhile a moderately lower ρs will not significantly reduce the ductility.