Local buckling behaviour of stainless-clad bimetallic steel built-up square hollow section stub columns

Abstract

The local buckling behaviour and design of built-up square hollow section (SHS) stub columns made of the stainless-clad (SC) bimetallic steel is addressed in this paper by experimental and numerical investigations. A total of seven stub column specimens fabricated from hot-rolling bonded SC bimetallic steel plates with nominal thicknesses of 8 mm and 13 mm were tested and analysed.​ Precise measurements of dimensions and geometrical imperfections of the specimens were conducted with the assistance of a non-contact 3D laser scanner. The scanned data was processed by a novel approach to provide a more accurate analysis of imperfections. Finite-element (FE) models with geometric imperfections obtained from 3D-scanned data were developed and validated against the dependent test results herein and independent ones. Comprehensive parametric studies considering various clad ratios, normalized plate slendernesses and steel grades were carried out by using the verified FE models. The applicability of current codified design methods to the SC bimetallic steel SHS stub columns was evaluated through comparisons with the numerical results. A normalized slenderness limit as well as an effective width formula were proposed based on the parametric studies and the evaluation of existing design methods. With improved efficiency and consistency, the design methods proposed herein can be utilized in the future application of the SC bimetallic steel structures.