Performance of Seismically-Compatible Fin Plate Joints under Fire Conditions

This paper compares the performance of fin plate joints designed with and without seismic considerations under gravity loading and fire conditions. The non-seismic design, following British detailing provisions, has a thicker fin plate located higher on the beam web and it positions the beam web closer to the column face compared to the seismic design detail based on New Zealand provisions. Finite elements in ABAQUS are used to model the subassembly, which is subjected to the ISO 834 fire with and without a cooling phase. The analyses indicate the same failure mode in both subassemblies, with yielding at the beam web top bolt hole in bearing and fracture of the top bolt in shear. However, under the same fire regime, peak compressive and moment demands of the seismic detail were approximately 25% less than those for the non-seismic detail. When subjected to heating only, time to runaway failure was similar for the seismic and non-seismic detail, occurring at 15.0 and 14.8 min into the analyses respectively. When a cooling phase was included, beginning 10 min after initial fire exposure, both subassemblies recovered without failure. A parametric study showed a larger gap between the beam end and column face decreased compression in the beam but did not significantly affect the failure characteristics of the joint. Use of thicker fin plates was also found to increase the time to failure. The results show that the seismic detailing provides limited improvement over the non-seismic detail for the analysed fin plates.