Parametric Finite Element Simulation Studies Investigating the Lateral-Torsional Buckling Capacity of Built-Up Steel I-Section Members

Current American and international approaches for the design evaluation of general built-up steel I-section flexural members against lateral-torsional buckling (LTB) have been well established for many years. Nevertheless, the differences in nominal strength predictions from various prominent standards are quite striking. Recent research in Europe as well as in North America has demonstrated opportunities for further improvement both in areas where existing calculations are recognized to be substantially conservative as well as in areas where the current design strength prediction equations may not properly capture the strength reductions associated with certain effects. Experimental and test simulation research is underway at the Georgia Institute of Technology to provide targeted benchmark data addressing the influence of various factors that can reduce the LTB resistance of built-up steel I-section members below the so-called “plateau” or full cross-sectional flexural resistance. This research provides targeted FEA parametric studies probing the influence of distributed yielding (inelastic Cb) and web shear distortional post-buckling effects on the LTB resistance of I-section members subjected to significant moment gradients, complementing and extending the results of the experimental testing program at Georgia Tech.M.S