Joint Instability in Lattice Structures — Lessons from a Recent Collapse *

Abstract

The investigation into the collapse of the 15th Maccabiah footbridge in Israel on July 14, 1997 revealed that joint rotation was ubiquitous in the failure mechanism, although it may not have been the actual trigger of collapse. The joining system employed in this double-layer grid structure is characterised by exceptionally low rotational stiffness and is thus particularly susceptible to joint instability mode of failure. The problem was exacerbated by several features, such as the introduction of substantial camber to a joining system specifically designed for planar configurations, the subjection of compression members to flexure, and eccentric connection of supports. The paper stresses the importance of designing rigidity into prefabricated space truss systems and the need for the explicit incorporation of joint instability considerations in codes of practice and in standard design practice.