Fire after earthquake robustness evaluation and design: application to steel structures

The occurrence of fires breaking out during a seismic event, or even delayed after an earthquake represents a common circumstance in earthquake prone Countries, which must be adequately taken into account as a possible design scenario. In fact the behaviour in fire of structures that have been damaged by earthquakes changes as respect to the undamaged ones, since the earthquake-induced damage makes the structure more vulnerable to fire effects. In view of the current seismic design approach, where a certain extent of damage in case of severe earthquake is acceptable, the analysis of the behaviour of structures under the effect of fires in combination or following an earthquake is a significant research field, which is not yet fully explored. The robustness assessment under fire of structures already damaged to different extent by the seism, through a performance - based approach, is required. The procedure should be valuable as a design tool, as well as a vulnerability evaluation of the built heritage against FFE. In this paper the proposed general methodology is exemplified with regards to steel structures.