Experimental investigation of cold-formed lean duplex stainless steel beam-columns

Abstract

This paper describes a test program on cold-formed lean duplex stainless steel members in combined compression and minor axis bending. The test specimens were cold-rolled from flat strips of lean duplex stainless steel grade EN 1.4162. In this study, square and rectangular hollow sections were compressed at different eccentricities, in order to obtain a beam-column interaction curve for each series of tests. Initial overall geometric imperfections of the members were measured prior to testing. The ultimate loads and the failure modes of each specimen were obtained. The observed failure modes include local buckling, flexural buckling and interaction of local and flexural buckling. The test strengths obtained from this study and other available data were compared with the design strengths predicted by the American Specification, Australian/New Zealand Standard and European Code for stainless steel structures. It should be noted that these specifications do not cover the material of lean duplex stainless steel. Therefore, the suitability of the beam-column design rules in these specifications for lean duplex stainless steel is assessed in this study. Generally, these specifications are capable of predicting the beam-column strengths of the lean duplex stainless steel test specimens, and the design rules in the specifications are considered to be reliable. It is observed that the European Code generally provides quite conservative predictions for the beam-column specimens compared to the American Specification and Australian/New Zealand Standard predictions.

Behaviour of structural stainless steel cross-sections under combined loading – Part II: Numerical modelling and design approach

“…Although a number of established structural design codes for stainless steel exist, previous studies [5][6][7][8][9][10][11][12] have highlighted limitations and undue conservatism in some of their provisions. This has prompted research aimed at broadening the scope and enhancing the efficiency of these codes.…”

Testing and numerical modelling of austenitic stainless steel CHS beam–columns

“…The strain gauge values were employed to determine the actual initial loading eccentricities, according to Eq. (1) [31,32], in which I is the second moment of area, ε max and ε min are the strain gauge values at the maximum compressive fibre and the maximum tensile (or the minimum compressive, in some cases) fibre, respectively, Δ is the lateral deflection at mid-height, ω g is the initial global imperfection at mid-height and N is the applied load. Note that these determined eccentricities are employed in the numerical modelling in Section 3 and the design calculations in Section 4.…”

Structural behaviour of stainless steel elements subjected to combined loading

“…The experimental data were collected from the literature and included tests on austenitic (Talja and Salmi, 1995), duplex (Huang and Young, 2014b;Lui et al, 2014) and ferritic (Zhao et al, 2016e) stainless steel SHS and RHS beam-columns, while the numerical data were generated through parametric studies. In the parametric studies, the outer width of the modelled cross-sections was set equal to 100 mm while the outer depths ranged from 100 mm to 200 mm, leading to cross-section aspect ratios between 1.0 and 2.0.…”

“…The final expression for calculating the initial eccentricity about each axis of buckling is defined by Equation (3.3), which is similar to those in (Lui et al, 2014;Huang and Young, 2014b) considering the determination of actual initial loading eccentricities for long beamcolumn tests. The calculated e 0 and measured e m eccentricities were in good agreement, and are reported in Tables 3.9 and 3.11 for uniaxial bending plus compression tests and for biaxial bending plus compression tests, respectively.…”

“…The present numerical modelling programme was performed using the nonlinear finite The adopted material properties for the present numerical simulations were taken from previous tests on stainless steel SHS and RHS beam-columns (Huang and Young, 2014b;Zhao et al, 2015a. Table 7.1 summarises the employed material properties for each stainless steel grade.…”