Cyclic loading tests on welded connections of stainless-clad bimetallic steel and modelling

Abstract

Bimetallic steel is an advanced high-performance (HP) laminated steel that may balance well performance against production cost, and has great potential for practical use in structural engineering, particularly for stainless-clad (SC) ones. Welding is the most important connection technique for fabrication of such steel members because preparation of holes within the steel plate for mechanical fasteners may expose the substrate and thus destroy the corrosion resistance. The present paper aims to clarify mechanical performance of butt welded connection of the SC bimetallic steel that requires special welding configurations, particularly under seismic loadings. The butt welded connections are firstly tested for welding procedure qualification. Based on subsequent monotonic and cyclic test results, failure modes are clarified, and their mechanical properties are analysed in terms of cyclic and envelop curves. It is indicated that welded connections of the SC bimetallic steel plate are adequate for structural usage under earthquake; their cyclic hardening effects are remarkable, and the envelop curves can be well described by using the Ramberg-Osgood (R-O) model. An adapted cyclic constitutive model based on the Chaboche model is proposed with parameters being determined through non-linear fitting of cyclic test results, and its accuracy and adequacy are verified. Additionally, the butt welded connections exhibit more significant isotropic and kinematic hardening effects compared with the SC bimetallic steel plate. Research findings herein provide important evidence for adequacy of the SC bimetallic steel welded connections applied in seismic regions, and also provide accurate constitutive models for predicting their cyclic behaviour.