Hysteretic performance of Q690 high-strength steel box-section columns with slender webs

Abstract

High-strength steel (HSS) has a higher yield-tensile strength ratio and a lower fracture elongation than conventional mild steel, resulting in poor ductility in comparison to the latter. This paper aims to investigate the hysteretic performance of Grade Q690 steel welded box-section columns with slender webs. Four full-scale specimens were subjected to low-cycle horizontal reciprocating loading tests, and the failure mode, evolution of plasticity in the cross-section, energy dissipation capacity and ductility were studied. A finite element modeling procedure verified from the test results was used for a more extensive parametric analysis, and the influence of the width-to-thickness ratio, the axial compression ratio and the column slenderness ratio on the evolution of plasticity in the cross-section as well as the ductility were studied. The results show that plastic local buckling dominates the failure mechanism of welded box-section columns with slender webs. With an increase of the width-to-thickness ratio, axial compression ratio and column slenderness ratio, the evolution of plasticity in the cross-section and the ductility performance of the column gradually deteriorate, and the ductility coefficient within the selected parameter range is small, but it still has the capacity for energy dissipation. Limiting the axial compression ratio and width-to-thickness ratio to meet the requirements of elastic–plastic inter-story drift, HSS box-sections with slender webs can be incorporated in seismic design with low ductility requirements based on the concept of seismic performance design. In addition, a prediction formula for the ductility coefficient is proposed, which can provide a reference for the application of high-strength steel box-section beam–columns with slender webs in seismic design.