Structural Integrity of Bolted Glulam Frame Connections Reinforced with Self-Tapping Screws in a Column Removal Scenario

Abstract

An experimental study has been carried out to investigate the behavior of glulam beam-to-column bolted connections subjected to monotonic loading in a column removal scenario. Eight test groups, each including four replicates of a wood-steel-wood glulam bolted connection configuration, were experimentally examined. The connections in four test groups were reinforced perpendicular to wood grain with self-tapping screws (STS). Test results showed that in the event of a column removal, the connections behaved as semirigid connections with considerable moment-resisting capacity, unlike typical beam-to-column timber connections that are assumed to be perfectly pinned. Experimental results also revealed that increasing the number of bolt rows from two to three rows, with each row having two bolts, increased the moment-carrying capacity of both unreinforced and reinforced connections with increments greater than those obtained by increasing the bolt end distance from four to five times the bolt diameter. Most importantly, STS-reinforced glulam connections manifested considerably increased moment-carrying capacities compared to the respective unreinforced connections by a factor ranging between 1.30 and 2.4. This has proven the ability of such glulam frame connections to redistribute the applied load and successfully transfer it to adjacent structural elements in case of column removal that could be caused by fire, explosion, or accidental damage.