A Finger Joint Connected (FJC) Wood Truss System

A new finger joint connection for all-wood trusses employs short fingers to bond the end of the tension web to the edge or face of the chord and the end of the compression web to the tension web. This system transmits web-to-web forces directly, develops primarily compression and shear stresses on the finger joints and avoids or minimizes tensile force components perpendicular to the grain. Both flat and pitched trusses can be designed with this connection system. The shear strength of FJC truss connections, determined in a special test fixture, ranged from 1100 to 1980 psi. Similar shear values were also obtained by subjecting short truss sections to racking loads. Tension and tensile-shear values obtained with the test fixture generally ranged from 500 to 1100 psi, indicating that moderate tensile stresses on truss joints could be tolerated. Several full-size flat and pitched trusses were test loaded. Truss deflections were similar to commercial pin-connected and glued plywood gusset connected trusses. In addition, high-performance trusses can be designed with FJC connections using present MSR lumber grades.

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