Behavior of fiber-reinforced composite beams with mechanical joints

The fundamental behavior of the fibre reinforced composite beams with mechanical joints was examined using coupon and full-scale specimens. The effect of applied bolt torque, the contribution of adhesive bonding, and the number and configuration of bolts on the load capacity and failure mode of the double-lap bolted joints were investigated. The results showed that at different levels of applied bolt torque (10, 15, 20 and 25 N-m), little friction resistance developed. A slight increase on the load capacity was however observed with increasing tightening torque. On the other hand, the mechanical joints using bolts accompanied by adhesive bonding provided resistance against slipping. The flexural behavior of full-scale fibre composite beams with joints at midspan connected with bolts alone and a combination of bolts and epoxy was further examined. The beams connected using bolts and epoxy exhibited the same strength and stiffness as the beams without joints while using bolts alone resulted to a beam with only 65% of the stiffness of those without joints. This showed that the combination of bolts and epoxy adhesives could provide a reliable connection method for fibre reinforced composite beams.