The continuous strength method for lateral-torsional buckling of stainless steel I-beams

Stainless steel is now widely used in construction as structural members in recognition to its unique beneficial properties such as corrosion resistance, higher strength, ductility, and negligible maintenance cost. Recent research on stainless steel has led to the evolution of a deformation based design rule, the Continuous Strength Method (CSM), which has been shown to perform well in predicting cross-sectional resistances but still requires considerable research to be used in predicting member resistances. The current paper proposes a new design method for lateral-torsional buckling (LTB) behaviour of welded stainless steel I-sections combining CSM design philosophy and traditional Perry-type concept used for column buckling. As part of the numerical study presented herein, nonlinear finite element (FE) models were developed and validated using available test results. Once the FE modelling technique was validated, a large number of reliable numerical results were generated to investigate effects of various factors on the resistance of members subjected to LTB. Obtained results showed that the cross-section slenderness (lambda) over bar (p), and the non-dimensional proof stress e have significant influences on LTB resistance. Effects of e was appropriately incorporated by introducing a correction factor to modify (lambda) over bar (p). As LTB curves were mostly affected by (lambda) over bar (p), it was included in the equation for calculating imperfection parameter eta(csm,LT), which is a key parameter to include member imperfections in Perry-type design equations. This new approach ensures appropriate utilization of strain hardening for stocky cross-sections and allows to avoid the complex process of calculating effective geometric properties for slender sections. All available test and generated numerical results were used to assess the performance the current European, the Australian and the proposed CSM based design rules for LTB. Comparisons clearly showed that the proposed approach performed significantly well in predicting the LTB response of stainless steel I-sections.