Experimental study on seismic behavior of high-strength circular concrete-filled thin-walled steel tubular columns

Abstract

This paper presents the results of an experimental study on the seismic behavior of high-strength circular concrete-filled thin-walled steel tubular (HCFTST) columns with ultra-large diameter-to-thickness (D/t) ratios exceeding the limitations of the current construction standards. Sixteen HCFTST columns with different combinations of D/t ratio, concrete cylinder compressive strength (fc), and axial compression ratio (n) were tested under constant axial compression combined with cyclic lateral loading. The ultimate failure state was achieved when the steel tubes ruptured severely and core concrete crushing occurred. The results from hysteretic curves indicated that the HCFTST columns with ultra-large D/t ratios displayed flexural failure and shear failure modes. Subsequently, the skeleton curve, ductility, energy dissipation capacity, and stiffness degradation were discussed in detail. Moreover, the effects of D/t ratio, concrete cylinder compressive strength and axial compression ratio on performance were investigated so that this work could serve as a basic reference to future studies, and a strength model was proposed to predict the moment-resisting capacity. The experimental investigation indicated that (i) using high-strength Q690 steel could significantly contribute to a larger elastoplastic deformation capacity and delay the onset of post-peak behavior, even though a lower ductility capacity was provided; (ii) the proposed strength model could satisfactorily predict the moment-resisting capacity; (iii) the out-of-code HCFTST columns with reasonable design could demonstrate favorable seismic behavior and could be accepted as aseismatic components in earthquake-prone regions.