Fire behaviour of damaged wood-steel-wood beam connections retrofitted with self-tapping screws-- experimental study

This experimental study aimed to investigate the structural fire behaviour of damaged glulam beam connections retrofitted using self-tapping screws (STS). Four full-size glulam beam-end bolted connections with wood-steel-wood connection configurations using four or six bolts arranged in two different bolt patterns were examined. All connections were retrofitted using STS after being deliberately damaged through physical testing until failure. In a subsequent stage, the retrofitted connections were experimentally tested under standard fire exposure while subjected to the maximum design load of the weakest, undamaged, unreinforced connection configuration. The influence of the application of STS in terms of preventing wood-splitting propagation and maintaining reasonable fire resistance for the retrofitted connections was experimentally investigated and proven in this study. Results show that the retrofitted glulam beam connections maintained a minimum of approximately 67% of the failure time of identical but undamaged, unreinforced connections under standard fire exposure.