Finite element study of steel beams reinforced while under load

The results of a finite element study on the behavior and capacity of W-shape steel beams reinforced with welded plates while under load are presented. The finite element model was verified using test results obtained from a concurrent experimental study involving the testing of six beam specimens reinforced while under load. The verified model was then used to investigate the effect of several influential parameters with the focus on reinforcing patterns, preload magnitudes at the time of welding, and initial imperfections of the unreinforced beam. Numerical results show that an increase in the preload magnitude at the time of reinforcing resulted in a reduction in the ultimate capacity of reinforced beams failing in lateral-torsional buckling. This reduction was more significant for a beam reinforced with a plate welded to its tension flange than that reinforced with a plate welded to each of its flanges. The variation of initial imperfections of unreinforced beams was also shown to affect the ultimate capacity of the reinforced beam. For beams failing by yielding, the effects of preload magnitudes and initial imperfections were marginal.