Fire performance of concealed wood-steel-wood connections with perpendicular to grain reinforcement

This study aimed to investigate the fire behaviour of concealed connections by considering the effects of parameters such as the number of bolts, bolt pattern and load ratios. The connections used for this study were fire-protected glulam beam-to-column reinforced concealed connections loaded perpendicular-to-grain in flexure bending. Eight (8) full-scale fire tests were conducted involving four different connection configurations. The load ratios applied during fire testing were 60%, 100% and 130% of the ultimate design load capacity of the weakest unreinforced connection configuration. The test results showed that the failure times of all the tested beam-to-column concealed connections were more than 50 minutes. Specimens with bolt pattern P1 performed better than bolt pattern P2. The results showed that increasing the number of bolts improved the failure time. Increasing the load ratio decreased the failure time of the connections. The brittle failure modes encountered in unreinforced concealed connections was prevented using STS.