Experimental Hybrid Testing of a Concrete Filled Steel Tube (CFST) Bridge Pier Subjected to Vertical and Horizontal Ground Motions

Hybrid simulation is a form of advanced testing that combines both numerical and experimental techniques to achieve an economical seismic response assessment of structures. The technique utilises the best feature of computer simulations and combines these with experimental testing. This makes hybrid simulation a powerful platform for experimentally studying the seismic responses of structures to collapse. This paper presents an application of hybrid simulation for tracing the seismic responses of a concrete filled steel tube (CFST) column subjected to combined horizontal and vertical ground accelerations. A state-of-the-art testing facility, known as the multi axis substructure testing (MAST) system, was used to impose complex boundary effects on the physical specimen using mixed load and deformation modes. The column was subjected to five increasing ground motion levels. During the test, the column experienced large axial force variations of up to 2.2 MN and reached a maximum drift of 8.8% without significant damage. The results demonstrate that this CFST column is thus capable of resisting large compression and tension forces, offering high levels of ductility without collapse.