Earthquake Damage to Passive Fire Protection Systems in Tall Buildings and its Impact on Fire Safety

This paper investigates the extent to which earthquake damage to passive fire protection reduces fire safety in tall buildings. Currently in New Zealand there are no legislative design criteria for the event of fire following an earthquake. Some passive fire protection systems such as gypsum plasterboard walls are very vulnerable to earthquake damage. This damage can lead to a reduction in the fire resistance ratings, thereby threatening the fire safety of the occupants, particularly for walls protecting the escape routes from buildings. In this study a model was developed to calculate factors of safety as a ratio of available and actual escape times in burning buildings. In a worst case scenario, the model considered the possibility of fire occurring on the ground floor adjacent to the main escape routes from the buildings. The study included the results of recent research which shows that gypsum plasterboard walls, not damaged by earthquake but exposed to realistic fires, may fail in much shorter times than the published fire resistance ratings. It was concluded that for fire following an earthquake in buildings greater than about ten stories, in which the sprinklers do not operate and the walls are damaged, the occupants may be unsafe because the expected escape time is greater than the expected failure time of the fire rated walls surrounding the escape route.