Blast performance of concrete slabs in combination with fire

This paper makes reference to the project "Strategisch basisonderzoek" (IWT-SBO No 080010), Fundamental design approaches for improvement of the fire safety in car parks, funded by IWT-Vlaanderen in the 'SBO' framework (Strategic Basic Research). It deals with the determination of the loading bearing capacity of reinforced concrete hollow core slabs when they are submitted first to fire and secondly to a blast load. The software Autodyn (Ansys) is used to perform the numerical simulations. This software permits to analyze transient phenomena such as an explosion, where material properties change very rapidly (milliseconds). On the other hand, fire does not change properties that fast. The paper focuses on the solution of this difficulty by the performance of the preliminary analysis of the changes of material properties due to fire, which allows to determine the proper input for the numerical blast analysis by means of Autodyn. Full scale experimental campaigns have been conducted in order to validate numerical models for both explosion and fire phenomena. It is observed that the numerical part corresponding to blast load analysis matches significantly with the experimental predictions. The main conclusion is that crack patterns and blast load bearing capacity is not altered by fire with temperatures below 400°C.