ASYMMETRIC-COLLAPSE OF BRACED TUBES

Braced metallic tubes are used to dissipate kinetic energy in impact a ttenuation devices used in transportation safety applications. Tt is a n experimentally observed fact that these braced tubes collapse asymme trically; even under symmetrical loading conditions. This paper examin es the energy dissipation characteristics of such a tube when braced a cross its diameter and subjected to lateral plate loading conditions. Upper- and lower-bound limit analysis approaches are used to first det ermine the initial asymmetric collapse load of the tube with diametric al bracing oriented perpendicular to the line of action of the loads. Then, the equivalent structure technique (EST) and finite-element prog ram, ABAQUS, are used to determine the postcollapse characteristics of the tube. Finally, these mathematical and numerical model predictions are compared with experimental results to demonstrate the accuracy of the modeling process.