Seismic behaviour of stainless-clad bimetallic steel welded box-section beam-columns

Abstract

The stainless-clad (SC) bimetallic steel is an advanced high-performance steel with high strength and outstanding corrosion-resistant performance. It is especially competitive in the application of structures with demands of high corrosion resistance. However, the current research on SC bimetallic steels mainly focuses on the material level rather than the structural level, and it is not clear whether the excellent performance of materials can be reflected in the seismic behaviours of members. Thus, cyclic behaviours of SC bimetallic steel members need to be thoroughly investigated to fill the research gap and expand the application fields of this steel in the seismic region. To this end, this paper aims to study the cyclic behaviour of SC bimetallic steel box-section beam-columns subjected to combined constant axial load and low-cycle reciprocating lateral load through full-scale tests and finite element (FE) models. Four specimens were tested, and the influence of the width-to-thickness ratio of component plates was clarified through comparative research on the test processes, buckling details, hysteresis curves, strain curves, energy dissipation and ductility performance. Moreover, a refined FE model adopted single-layered modelling or double-layered modelling was developed respectively; and then, the model validation, the shear stress distribution at the bonding interface and parametric analyses were carried out. Research showed that the SC bimetallic steel beam-columns exhibit good energy dissipation and seismic behaviour under cyclic loadings; the smaller width-to-thickness ratio or axial load ratio could result in the plumper hysteresis curves, more sufficient energy dissipation and superior ductility performance; the ductility performance of SC bimetallic steel column was significantly improved; the ductility-based design approach proposed herein could approximately quantify the ductility performance of SC bimetallic steel box-section column, which could provide a reference for the seismic design.