Effect of earthquake damage on the behaviour of composite steel frames in fire

Fire loading following earthquake loading is possible in any building in a seismic prone area. However, most design approaches do not consider fire following earthquake as a specific loading case. Moreover, seismic design philosophies allow a certain degree of damage in structural elements which make structures more vulnerable when subjected to post-earthquake fire. This study uses three dimensional numerical models to investigate the effect of earthquake damage on the fire resistance of composite steel-frame office buildings. Two types of earthquake damage, fire insulation delamination and residual lateral frame deformation, are investigated. It is concluded that earthquake damage can significantly reduce the fire resistance of composite buildings, with delamination of fire protection having the greatest effect. The results of this study can be used by designers to improve the post-earthquake fire resistance of composite buildings.