FRP-to-softwood joints: experimental investigation

A proper understanding of the interfacial behaviour between timber and bonded fibre-reinforced polymer (FRP) composites will assist in the rational and optimal design of FRP strengthening works for timber structures. To enhance this understanding, a series of single-lap FRP-to-timber joint shear tests are reported herein in which the strength of the bond between the FRP and timber is examined. The shear tests are conducted on softwood (Pine) which has been strengthened with carbon FRP with the main test variables being the FRP bond length and the growth characteristics of the timber. Extensive strain gauging of the FRP has enabled the onset and propagation of debonding cracks to be monitored. An effective bond length is identified, however, the results also show that timber is a variable material which requires continued investigation.