Triple-actuator apparatus for strength experiments of cold-formed steel members in combined loadings

Cold-formed steel members are likely to undergo complex combinations of loadings such as bending, shear, and compression. In the literature, numerous test rigs have been developed to test members subject to both isolated and combined actions. These apparatuses are commonly employed for testing combined two actions, such as shear-bending and bending-compression. However, as of today, there is no test rig specifically designed for more complex combined actions including compression, bending and shear. This paper introduces an innovative experimental apparatus namely a “Triple-Actuator Test Rig”, recently developed at the University of Sydney, with a focus on investigating the ultimate behaviour of cold-formed steel channel sections subjected to combined actions of shear, bending and compression. The combined shear and bending is conducted by using two vertical dual actuators, and the axial compression force is applied using an additional horizontal actuator. To elucidate the mechanism of the new apparatus in capturing various combinations of actions, linear static analyses are performed under different cases of combined loadings. Furthermore, detailed information on test controls and procedures is provided. An experimental validation is also conducted to demonstrate the performance of the test rig in investigating not only pure actions but also complex combinations of actions.