Epoxy-Repaired Bolted Timber Connections

A major maintenance cost associated with timber construction is the repair of structural members in which checking, cracking, and splitting have occurred, in particular, near bolted joint connections. The use of pressure injected epoxy to repair damaged timber connections has potential as a viable alternative to current repair procedures. To investigate the structural behavior of epoxy-repaired timber connections, a series of experimental studies were conducted to determine: (1) Epoxy-to-wood bond characteristics; and (2) behavior of epoxy-repaired bolted timber connections. Bond tests in both tension and shear showed that the epoxy-to-wood bond is at least as high as the allowable stress in the timber. Tension and bending tests of simple bolted joint connections were even more significant. Using a procedure of loading a defect-free joint to failure, repairing the joint by the epoxy injection method, and reloading the joint to failure, it was found that a 30%-60% increase in strength is obtained, and the stiffness of the joint is increased.