Modeling of metal-plate-connected wood truss joints: Fid-Bau Portal

Modeling of metal-plate-connected wood truss joints

Vatovec, M. / Miller, T.H. / Gupta, R.

A commercially available, three-dimensional finite-element analysis software was used to model the load-displacement behavior of metal-plate-connected joints in wooden trusses. Model features included consideration of material properties, teeth-to-grain-to-direction-of-force orientation, wood-to-wood interaction, and gaps between wood members. To simulate wood-to-plate interaction, the main feature of the model, each tooth of the metal plate is represented by one set of three spring elements. Each spring element accounts for tooth-wood behavior (stiffness) in one major plate direction: parallel to slots, perpendicular to slots in the plane of the plate, and perpendicular to the plane of the plate. For each element, nonlinear load-slip (stiffness) curves are defined based on tension splice joint tests at various teeth-to-grain orientations. One advantage of the spring-element-based approach is that once incorporated in the model, the per-tooth stiffness need not be adjusted for different loading conditions applied later to the joint model. The load-displacement results from the model compared very well to the experimental results from tensile bending tests of splice joints with several different teeth-to-grain orientations. For the investigated plate size, the governing factor for joint behavior was the plate-wood interaction (spring elements). Several possible model simplifications were investigated. Models with lumped teeth properties predict joint load-displacement behavior reasonably well.