Fiberglass-reinforced bolted wood connections

This research investigated using fiberglass reinforcement to enhance the load-carrying capacity of bolted wood connections. Specimens were prepared from standard 51-by 102-mm (nominal 2- by 4-in.) lumber from the spruce-pine-fir lumber grouping. Matched specimens were reinforced with one, two, or three layers of bi-directional fiberglass cloth. Resulting test specimens were configured as a connection that was in accordance with current design specifications. A total of 80 single-bolt, double-shear connections were tested: 40 with parallel-to-grain and 40 with perpendicular-to-grain loading. Results indicate that connection strength increases as the number of layers of fiberglass reinforcement increases. The ultimate strength of a three-layer reinforced connection was 33 percent greater than the nonreinforced connection for parallel-to-grain loading, and more than twice the strength for perpendicular-to-grain loading. More importantly, the reinforcement changed the mode of failure from an abrupt, catastrophic failure associated with tension perpendicular-to-grain stresses to a ductile failure associated with bearing-type failures.