Design of stainless steel RHS beams, columns and beam-columns

The main purpose of the study was to obtain test data and develop design rules of the Eurocode 3 Annex S (present Part 1.4) proposal: Design of steel structures: The use of stainless steels (1993). The study is limited to rectangular hollow sections (RHS) which are manufactured by roll-forming from AISI 304 (X4CrNi18-10) austenitic stainless steel. The main challenges are the effects of work-hardening during cold-forming and the nonlinear stress-strain behaviour, which have an effect on the plastic design, on the elastic stability design, and on the determination of deflections. First the study reviews the different design expressions given in Eurocodes, in the ANSI/ASCE code and those in some other publications. Then the test programme and test results are described. Altogether 39 tests including concentric compression, eccentric compression, bending and web crippling tests for RHS members of sizes 60x60x5, 150x100x3 and 150x100x6 have been carried out. In addition six concentric compression tests and one bending test for a cross-section of 80x80x3 referred to in the literature have been studied. The comparisons with the test results demonstrated that the Eurocode 3 Annex S proposal is very inaccurate for austenitic stainless steel RHS members. In many cases the underestimation is remarkable, and in some cases the predictions may also be uncertain. The plastic reserves are always underestimated, the expressions for the flexural buckling of slender beams lead in some cases to uncertain results and the estimation of the deflections is always uncertain. More accurate design expressions are proposed. They are based on the 0.2 %-proof stress determined by the help of a compressed stub column and on the reduced modulus of elasticity