An investigation of FRP reinforced glulam bolted connections

Abstract

Wood is often limited in structural applications to relatively small structures due to its lack of homogeneity and low strength compared to steel and concrete. Wood can become a more versatile material if used with Fiber Reinforced Polymers (FRP) to form a composite. This thesis presents the results of an investigation of the increase in yield strength, ultimate strength, and change in yield mode of wood connections when reinforced with FRP. Specifically, this thesis investigates the effects of FRP reinforcement in Laminated Veneer Lumber (LVL) bolted connections under double shear loading. The FRP investigated consists of uniaxial carbon fibers embedded in a two-part epoxy. Sixteen sample wood connections were tested. Eight samples were reinforced with FRP such that the carbon fibers were parallel to the wood fibers. Eight samples tested were not reinforced and used as a means of comparison. Three sizes of bolts and two failure modes were investigated. All materials chosen are readily available and affordable in the current construction market. Finally, the results of a cost vs. strength gain analysis are presented. FRP reinforcement of the glue-laminated wood connections under double shear loading resulted in an increase in yield strength and ultimate strength of all connections tested when compared to unreinforced samples with the same properties. The addition of FRP reinforcement changed the yield mode for some samples. However, it seems that FRP reinforcement is only cost effective in situations in which a higher ultimate strength is desired, rather than a higher yield strength or change in yield mode.