The cost of satisfying design requirements on progressive collapse resistance – Investigation based on structural optimisation

Abstract

This work is concerned with the explicit treatment of progressive collapse resistance within the structural design process. Progressive collapse resistance is associated with the damage tolerance of a structural system and controls the ability of the system to sustain local damage by absorbing the potential of triggering system collapse and suffering disproportionally large consequences. This work focuses on the design of elastoplastic steel frames. The measure of progressive collapse resistance employed is expressed as a ratio comparing the limit loads obtained with elastoplastic analyses of the intact structure and of an artificially damaged structure (‘damage’ is caused by the notional removal of a column from the intact structure). This measure is used to incorporate a constraint on progressive collapse resistance into a structural design optimisation formulation, which – in its classical form – takes only standard design code constraints into account and aims at minimising the structural cost. The developed optimisation approach is capable of producing cost-effective structural designs with acceptable system damage tolerance. By enforcing the satisfaction of the additional design requirement on progressive collapse resistance, structural cost is inevitably increased due to the need for extra material. This increase is quantitatively explored with the presented structural design optimisation approach.