Behavior of Steel Column-Trees under Fire Conditions

A numerical study on the fire performance of bolted splice connections is presented. A finite element (FE) model, incorporating geometric and material nonlinearities, nonlinear contact interactions, and elevated temperature properties of steel was developed for undertaking fire response analyses. The model was validated by comparing its predictions with experimental data. To investigate the effect of critical factors on the behavior of beams and their bolted splice connections, parametric studies were performed using the validated model. Results from the parametric studies indicate that the gaps between link and stub beams, free length of flange splice plate, and thermal gradients developed during fire exposure have a significant effect on fire response of bolted splice connections. The beam fails when deflections exceed the limiting value specified in the current standard. Results also indicate that temperature gradients, lateral restraints, and levels of axial stiffness significantly influence the fire behavior of the beams in column-tree moment-resisting frames.