Triangular Truss Joints Using Rectangular Tubes

This paper deals with the behavior and design of welded joints to the tension chord of triangular trusses, with two Warren-type web planes and a single tension chord, made of rectangular tubes (hollow structural sections or HSS). Experimental programs are outlined in which simplified double-T joints and triangular truss segments with double-K gap joints were tested. Parameters investigated include the gap size, the web-member-width–to-chord-width ratio, the chord-wall-width–to-thickness ratio, and the angle between web planes. The mechanics of deformations of the double-T and double-K joints are discussed in relation to yield line theory, and this theory is shown to give a good prediction of the experimental joint stiffnesses and strengths. Strength equations are proposed to cover tension chord gap joint behavior with respect to chord wall bending and a design example is outlined.