Design examples for HSS trusses

Abstract

Following recent international consensus on a series of complex design formulae for the static strength of welded joints in hollow structural section (HSS) trusses, design aids and design procedures compatible with CAN3-S16.1-M84 and based on these recommendations have been produced for implementation in Canada. This paper formally illustrates the use of these design aids by undertaking design examples for rectangular hollow section (RHS) chord planar trusses. The design aids discussed by the writer are in the form of charts for manual design and an interactive microcomputer program for automated truss design. Although the design method is much more rigorous than that presently used by Canadian structural engineers, who typically follow the guidelines of the Stelco HSS connections manuals, it vividly illustrates to the user the principal parameters affecting the strength of welded joints in HSS trusses. The paper also demonstrates that the joint strength criteria frequently control the selection of members, thereby making the design and checking of such joints the responsibility of the design engineer rather than the fabricator. Key words: hollow structural sections, tubes, welded joints, trusses, limit states design, design aids.