Cyclic loading tests on concrete-filled double-skin (SHS outer and CHS inner) stainless steel tubular beam-columns

Abstract

This paper reports a series of cyclic loading tests on concrete-filled double-skin stainless steel tubular (CFDSST) beam-columns with square hollow section (SHS) outer and circular hollow section (CHS) inner. A total of 24 specimens were tested under constant axial compressive load and cyclically increasing flexural loading to investigate the structural performance of the composite beam-columns. The test parameters included the axial compressive load level (n), the thickness of the outer stainless steel tube (to), the hollow ratio (χ) and the concrete strength (fcu).The failure modes and hysteresis curves of the concrete-filled double-skin stainless steel tubular (CFDSST) beam-columns have been reported. Based on the test results, the effects of the test parameters on the lateral load (P) versus lateral displacement (Δ) envelope curves, ductility coefficient, dissipated energy and stiffness degradation have been investigated. The results shows that, generally, the axial compressive load level and thickness of outer tubes have a primary influence on the behavior of the test specimens while the hollow ratio and the concrete strength have a little effect when the axial compressive load level is low. Finally, comparisons of initial section flexural stiffness and ultimate bending moments of the beam-columns which were obtained from the tests are made with the predicted ones using the existing design codes and design method.