Quasi-Static Strengths and Failure Modes of Tight-Fitting and Round-End Metal-Plate Wooden Truss Joints

Abstract

An experimental study was conducted to investigate whether existing industry design procedures for tight-fitting metal plate connector truss joints can be applied to the design of joints made with round-end webs. Four joint configurations were tested with a range of connector-plate sizes: 45° with web in tension, 45–45° with one web in compression and the other in tension, 45–90° with the 45° web in compression and the 90° web in tension, and 45° with the web under compression. In total, 87 tight-fitting and 171 round-end joints were tested. As expected the tight-fitting joints were stronger and stiffer than round-end joints. Both the shear strength of the metal plate connector and the teeth pullout strength were smaller in the round-end joints than in the tight-fitting joints. The line contacts between the round-end webs in compression produced greater crushing of the wood, causing buckling of the connector plates, and reducing the ultimate loads on these joints. Design guidelines are suggested for round-end joints.