Experimental research on concrete-filled RPC tubes under axial compression load

An innovative composite column, named concrete-filled RPC (reactive powder concrete) tube (CFRPCT), is presented in the paper. In this hybrid system, high-strength spiral hoops are arranged in the prefabricated RPC tube and then concrete is poured in the RPC tube. Besides serving as formwork, the RPC tube can provide excellent stiffness and can directly carry considerable axial load attributed to its ultra-high compressive strength. Moreover, high-strength hoops in the RPC tube provide lateral confinement for the inner concrete. A total of 27 large-scale columns were tested under axial compression load, to investigate the composite effect between RPC tube and inner concrete. The results show that axial load carrying capacity of the CFRPCT columns is about 6.0% higher than the total capacity corresponding to the hoop-confined column and the hollow RPC tube. The CFRPCT system effectively combines the high strength of RPC and hoop confinement. Based on experimental findings and modified existing model, a confinement model was proposed to predict the axial load carrying capacity of CFRPCT columns and it was also validated with experimental results. This CFRPCT system provides a type of cement-based composite column, which owns high compressive performance, excellent durability and corrosion resistance.