Concrete Filled Cold-Formed C450 RHS Columns Subjected to Cyclic Axial Loading

Abstract

This chapter describes a series of static and cyclic axial compression tests on empty and concrete-filled columns made from cold-formed C450 Rectangular Hollow Section (RHS) profiles. It also demonstrates that concrete filling increases the postpeak-load residual strength and reduces the rate of residual strength loss per cycle for thinner RHS columns subjected to overload cyclic situations. The tensile coupon tests were performed according to the Australian Standard AS1391 (SAA (1991)). The 0.2% proof stress was adopted as the yield stress for the cold-formed steel tubes. The average compression strength was found to be 44.4 MPa. A 1000 kN capacity Instron Performance Reckoner actuator was used together with an Instron 8500 controller to apply the cyclic axial loading. Two spring pots were used to measure the axial deformation and the mid-span lateral deformation. Inward folding mechanism with cracks was observed for the empty RHS under cyclic loading. The peak load for one RHS increased by about 58% due to the concrete filing. The increase in peak load for another RHS was about 23%.