A numerical investigation of post-earthquake fire performance of mass timber moment frames

Post-earthquake fire scenarios expose already damaged structural systems to subsequent thermal loads. For modern mass timber systems, where inelastic behaviour is concentrated within connections, the combined effects of seismic damage and fire are still not properly understood. This study presents a numerical investigation into the fire performance of seismically damaged glulam beam-column connections. A three-dimensional finite element model was developed in DIANA FEA and then validated to match previously conducted experimental fire test data for a bolted glulam connection. The validated model was then used to perform a parametric investigation in which seismic damage was represented through three progressive stages of reduction of the effective timber area that surround the connection, corresponding to the FEMA-356 performance levels. The results show that with increasing levels of damage, the rate of heat penetration into the connection also increased.