Deflection of Metal Plate Connected Wood Trusses with Nontriangulated Openings

Abstract

The behavior of metal plate connected wood truss joints surrounding the open area of attic type trusses under the action of dead and live loads is investigated through experimental tests of full-scale trusses and analytical simulation studies involving predictive stiffness models of the metal plate connections. An existing model to simulate partial rigidity for specific member connections at a joint is implemented into an analog system and analyzed with software designed specifically for use with metal plate connected wood trusses. The analysis of metal plate connected wood trusses in typical engineering design has typically assumed that non-heel joints are either fully pinned or rigid. This type of assumption greatly simplifies the truss analysis and design process, but as research shows, may not accurately reflect the deflection and distribution of internal forces. The axial and rotational deformations of the joint from the convergence of member forces directly effect the truss deflection as well as the distribution of internal forces. The effect of eccentricities at nontriangulated openings, where the configuration of the webbing is similar to a frame is of significant interest. Results suggest that modeling the joints of metal plate connected wood trusses with nontriangulated openings as partially rigid is necessary for estimating the overall maximum deflection.