Design of Lean Duplex Stainless Steel Tubular Sections Subjected to Concentrated End-Bearing Loads

This study presents the numerical investigation and design of cold-formed lean duplex stainless steel (CFLDSS) tubular sections subjected to concentrated end bearing loads, specifically end-one-flange (EOF), end-two-flange (ETF), and end loading (EL). Finite element models (FEM) were developed and verified against the test results of CFLDSS tubular sections subjected to the three loads. The FEM are able to predict the behavior of CFLDSS tubular sections in terms of ultimate strengths and web crippling failure. The verified FEM were used to perform an extensive parametric study that included a wide range of key parameters, including the ratios of flat web height to thickness, load bearing length to web thickness, and load bearing length to flat web height. Based on both the test and numerical results, new coefficients are proposed for the unified design equation and the direct strength method for the design of CFLDSS tubular sections subjected to the three concentrated end bearing loads. The strengths obtained from the tests and the parametric study were compared with the nominal strengths calculated using the design equations from current specifications and those in the literature, as well as those proposed in this study. Overall, the modified design rules provided more accurate predictions compared with the design rules in the current specifications and literature. The results showed that the proposed design methods are suitable for the web crippling design of CFLDSS tubular sections under the three concentrated end bearing loads.