An experimental investigation on strengthening single-bolted timber joints with externally bonded CFRP composites

Timber structures, especially those of historical value, may need to be strengthened or repaired due to various reasons such as improper original design, earthquake damage, or degradation due to environmental factors. Of particular vulnerability in timber structures is the joint region and as a result a strategy for easy strengthening and repair is required. Externally bonded fibre-reinforced polymer (FRP) composites, which have been applied abundantly to the strengthening of concrete structures to date, are a potentially viable solution although the proof of concept requires experimental verification. This paper reports part of the results of an experimental investigation conducted at The University of Hong Kong on the strengthening of single-bolted timber joints with different configurations of CFRP composites. Tests were carried out under monotonic load and the results show that with the proper arrangement of fibre, the strength of bolted timber joints may be enhanced. Selected load-slip curves are provided in addition to a discussion on the behaviour and failure modes of the test specimens. Finally the average shear stress induced between the CFRP and timber substrate is calculated.