Progressive Collapse Indicator

Abstract

Progressive collapse is a collapse where a local failure leads to a disproportionate collapse. Different terms like initial failure, propagation of failures and disproportionate damage are important aspects of such collapses. In current design practice, a method to measure a structures’ progressive collapse sensitivity in its early design phase and taking into account all aspects of a structures collapse resistance does not exist. The objective of this research is to develop a tool that takes into account all aspects of a progressive collapse and can aid the engineer in assessing a design, in its early design stage, on progressive collapse. At first, the initial failure is elaborated. Different events can cause the failure of elements. The probability an initiating event occurs at a certain element is different for each element. Mitigating measures can limit the chance of occurring for certain events. The initial events are applied on the model in 2 steps. First the location (or: element) of the event is chosen by a random selection method and a distribution of failure chances on the model. Second, the size of the damage is determined by applying a Gaussian curve over the model, both in x- and z-direction. This determines if adjacent elements, related to the removed element in step 1, are removed. The model is calculated by FEA-software. Only linear and first order calculations are considered. These limitations lead to inaccuracies of the results compared with reality. A stability analysis has been performed to determine the buckling lengths of columns with more accuracy. Catenary action is one of the main modelling methods in designing against progressive collapse. This method is implemented into the tool. Iteratively, the forces and deformations are calculated which develop during the occurrence of catenary action.