Space Truss Studies with Force Limiting Devices

Experimental test results are presented of the use of force limiting devices (FLD) on the compressive chords of two-layer space trusses. Two subassemblages and one full-scale truss were tested, and two types of FLD were used. The results are considered in terms of the truss load versus central deflection plots. These highlight the significance of lack of fit of members in causing initial member forces that furnish a reduction in truss load capacity at first yield, after which there may be no significant increased ultimate strength reserve. Conversely, when FLD's were used on the brittle-type compressive chords, improved overall ductility was obtained, and the deleterious effects of lack of fit were moderated owing to favorable force redistribution under ductile yield conditions.