Modelling of hysteresis behaviour of moment-resisting timber joints strengthened with FRP composites

The integrity of moment-resisting timber framed structures can be compromised in a seismic event due to damage of the joint region. Externally bonded carbon fibre-reinforced polymer (CFRP) composites offers an effective retrofit strategy for such joints and the concept has been proven in a limited number of experimental studies to date. There is a, however, a distinct lack of numerical modelling studies of the system. This paper therefore reports the numerical modelling of the hysteresis behaviour of FRP-strengthened moment-resisting timber joints utilising the finite element method. Three types of joints are investigated, namely (1) plain unstrengthened joints, (2) FRP-strengthened joints that do not experience degradation in strength, and (3) FRP-strengthened joints with strength degradation. The joints are subjected to a displacement controlled cyclic load and the moment-rotation responses are extracted from the finite element results. In addition, the dissipated energy of each joint relative to the joint rotation is also provided. The modelling procedure is shown to be effective upon comparison with test results when the joint rotation is within an acceptable range of seismic activity.