STR-912: EFFECT OF GEOMETRIC IMPERFECTION ON LATERAL TORSIONAL BUCKLING CAPACITY OF I-BEAMS

London

Lateral Torsional Buckling (LTB) is a mode of buckling that occurs when a flexural member undergoes both lateral deflection and twisting. LTB can be considered as a critical condition for laterally unsupported beams. Current design specifications in North America (AISC 2010 and CSA S16-14) for LTB of wide flange (W-shape) and welded wide flange (WWF-shape) beams were derived from study of beams subjected to uniform bending moment distributions along beams’ lengths. Past studies on laterally unsupported I-beams indicated that geometric imperfection could significantly affect the LTB capacity of the laterally unsupported beams. Thus, research on effect of geometric imperfections for rolled and welded shape beams under uniform bending moment distribution is required. This paper presents results of detailed sensitivity analysis of initial imperfection on LTB capacity of laterally unsupported beams. A nonlinear finite element model is developed using the commercial finite element software ABAQUS. In total, 30 laterally unsupported beams (15 W-shape and 15 WWF-shape) with different levels of initial imperfections are analyzed. The beams are considered simply supported with uniform moments applied at the ends of beams. Initial residual stresses in both WWF-shapes and W-shapes that are reported in the literature are included in the FE model.

https://ir.lib.uwo.ca/csce2016/London/Structural/64