Behaviour of ECC encased concrete-steel composite columns with high strength materials

The use of high strength materials in concrete encased steel composite columns can lead to many benefits in terms of economy and improved structural performance. However, due to the well-known strain incompatibility between high strength concrete (HSC) and high strength steel (HSS), their full plastic capacities in composite section cannot be fully developed. Therefore, most design codes restrict their use in composite columns construction. In this study, the potential of using HSS in conjunction with steel-polyvinyl alcohol (steel-PVA) hybrid fibre engineering cementitious composites (ECC) to confine HSC and to improve the performance of encased composite columns is explored. This paper presents the results of experimental investigation on the compressive behaviour of a new form of encased composite column using HSS encased by HSC and ECC. Axial compressive performances of ECC confined fully encased (ECC-FEC) and partially encased (ECC-PEC) composite columns are compared with bare HSS and HSC encased HSS composite columns. It was observed that the ECC encasement effectively controlled explosive brittle failure of HSC and significantly improved the failure behaviour, ductility and compressive toughness of encased composite columns.