Behavior of metal-plate-connected wood truss joints under wind and impact loads

The objective of this research was to understand the behavior of metal-plate-connected (MPC) wood truss heel and tension splice joints subjected to dynamic loads that simulated hurricane wind and impact loads. The general loading procedure was to ramp load the joints to dead/design load level, apply dynamic load, unload to zero, and finally apply ramp load to failure. The stiffness of the joints before and after the dynamic loads was compared. Hurricane wind loads caused an average increase in stiffness of 300 percent, likely due to wood densification near the metal teeth. The impact load caused a stiffness increase similar to that produced by the hurricane wind loads. Dynamic loadings on heel joints caused no significant strength degradation. For tension splice joints, the accelerated ramp load produced the same results as the static ramp load in one-tenth the time. It is suggested that the static tests of MPC joints may be conducted in 1-minute to failure, like lumber, instead of 10-minute to failure as recommended by the current standard.