All-Nailed Lumber Truss of 60 to 80-Foot Span

Describes lumber trusses for light-industrial buildings with 60- to 80-foot clear spans. A comparison is made of test data obtained with the model and with full-size versions. The models made of clear, dry lumber on the 1/12 scale truss failed only during application of 14-1/2 times the minimum design load of 80 lbs./ft. The performance of tests on the three prototype trusses of 60-foot span proved to be far more critical than the model tests. The all-nailed joints, with 5/8-inch plywood gusset and splice plates on both sides of the nominal 2-inch lumber and reinforced at the quarter-point and center-splice joints of the lower chord with 5/8–inch plywood plates, transmitted such forces as existed after application of the dead load and 4-1/4 times the minimum design load of 80 lbs./ft. without deforming excessively. The analysis of thrusts and shears in the truss members indicated that the semi-rigid all-nailed joints performed virtually like rigid joints. Field experience with trusses of the described design indicates that they can be assembled at the building site without difficulty, can be erected with a light crane at a rapid rate, and can be more economical than other trusses having similar performance characteristics.

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