An experimental investigation of double chord HSS trusses

The results of a series of five large scale experiments on Warren trusses comprised of square HSS and utilizing the concept of a double chord are presented. The trusses were simply supported and loaded at their top chord panel points, thus simulating gravity loading. It was found that the bolted type, the back-to-back with overlap configuration, and the back-to-back with stiffening plate all sustained a loading that caused a member failure. The joints showed little or no duress. On the other hand, the two standard type trusses suffered joint failures principally by chord shearing at the ends of the top chord. This amounted to a reduction in strength of about 20% of the values of the other trusses. In this paper some design details are presented to help alleviate the problem of inadequate end joint strength.