2019 CSCE Annual Conference - Laval (Greater Montreal)

2019 CSCE Annual Conference - Laval (Greater Montreal) Conference

Investigating the Response of Bolted Wood Connections to the Effects of Blast Loading

Mr. Andrew McGrath, University of Ottawa
Mr. Christian Viau, University of Ottawa
Dr. Ghasan Doudak, University of Ottawa (Presenter)

Wood in bending generally exhibits a brittle failure mode with little ductility. This is undesirable when a timber structure is subjected to intentional or accidental blast loading. A possible source of ductility is the connections between assemblies. By eliminating brittle failure modes in the connections and engaging the metallic fasteners in a combination of yielding accompanied with wood crushing, significant ductility may be obtained in the structural system.

The research work presented in this paper aims to investigate the response of wood connections subjected to blast loads through experimental investigation of bolted steel-wood-steel connections. Four different connection types have been investigated: wood crushing failure both parallel and perpendicular to the grain, as well as fastener yielding failure both parallel and perpendicular to the grain. Each connection configuration has been tested under static and dynamic loading regimes in order to determine the dynamic increase factor for each failure mode.

The dynamic testing has been conducted using the University of Ottawa’s shock tube facility. Through the rapid release of compressed air, the shock tube is capable of reproducing shock waves similar to those generated in far-field detonations of high explosives. The pressure at the end of the shock tube is collected through a load transfer device and applied onto the wood connection. The other end of the connection is supported on a reaction frame that is designed to withstand the high impact forces. The applied pressure, displacements, and reaction load were documented, and the results will be reported in the full-length paper.

Results so far show a significant dynamic increase in wood crushing strength; however, the dynamic failure mode is observed to significantly differ from that under the static testing regime for some of the configurations investigated.