The Influence of Travelling Fires on the Response of a Concrete Frame

Experimental and theoretical work, as well as real fires such as occurred in the Windsor tower and Tu Delft, show that compartment fires travel around the floor plate of structures. Despite this evidence, structural fire design almost without exception assumes uniform, single-curve design fires. This paper adopts an alternative methodology for studying the effect of fire on a concrete frame structure. The Oh floor (42 m by 28 m and 3.6 m high) of a nine storey building is analysed when subject to a variety of "travelling" design fires whose temperatures vary with space and time.

The structural effects on the frame of five travelling fires whose behaviour is based on fundamental fire dynamics are compared with the structural effects of uniformly distributed parametric fire and Standard Fire curves. Each part of the concrete frame is assessed using several different measures of structural behaviour for each fire scenario. The differences in the structural response for the multiple fires are then compared. Additionally, the structure is analysed after returning to ambient temperature for each fire scenario. This allows a residual-state analysis to be conducted on the structure. It is concluded that there are clear needs and benefits in using a travelling design fire as the basis for a comprehensive structural design.