Space Trusses with Brittle-Type Strut Buckling

Three experimental tests on nominally identical aluminum space trusses with constant section chords and webs have been compared with a simplified theoretical analysis. An idealized strut curve has been adopted to describe the brittle-type behavior of the compression chords. Collapse line patterns have been recognized for the type of truss considered; these patterns form the basis for the simple method of analysis proposed. The collapse line layout has a different form from that normally associated with slab collapse; the difference is attributed to the negligible torsional rigidity of the type of truss investigated. The analysis furnishes reasonable agreement with the experimental results, and draws attention to the importance of the strut characteristic in the post-ultimate range of behavior. The brittle-type strut characteristic leads to a situation where the theoretical estimate of the load at first yield may not be reached. Conventional elastic analyses may not be as safe as many designers assume for this type of truss.