Flexural behaviour of glulam panels under sequential fire and blast loading

This study presents an experimental investigation of glued-laminated timber (GLT) panels subjected to a real fire followed by far-field blast-type loading. Seven GLT panels extracted from the Mass Timber Demonstration Fire Test Program were exposed to one-sided fire until self-extinguishment and then tested under four-point bending with simply supported boundary conditions, statically as well as dynamically using the University of Ottawa Shock Tube testing facility. Failure modes in charred panels were characterized by flexural failure, consistent with uncharred panels' failure modes, with some charred panels exhibiting visible glue line separation. Static and dynamic resistance curves were characterized as linear elastic up to maximum resistance in panels. The average strength increase factor (SIF) obtained for the charred panels was 1.8. No statistically significant dynamic strength increase in flexural strength or stiffness was observed. The findings demonstrated that a single-degree-of-freedom model, used together with the Reduced Cross-Section Method, can be a reliable predictive tool with proper inputs to simulate the dynamic response of structural elements for fire-followed-by-blast loading scenario; a methodology which can be extended to other timber structural elements.