Investigation of the Mechanical Characteristics of Truss Plates on Fire-Retardant-Treated Wood

Abstract

Systematic comparison has been made of the influence of a fire-retardant treatment of stiffness and ultimate strength of metal plate connectors and nail-glued plywood plates. Matched, treated and untreated tensile specimens were made of Douglas-fir and souther yellow pine using long-tooth and short-tooth type connectors and plywood nail-glued plates. All tests were repeated at each of two wood moisture content levels. An overview of the test results indicates that slightly lower ultimate strengths can be expected when fire-retardant treated lumber is used. Joints made with fire-retardant treated lumber are somewhat stiffer than the controls at 20 percent moisture content but this difference is lost as the lumber dries.