Author: R. Plank
2 January 2018
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All the articles from the January 2018 issue.
Fire is a basic hazard which can devastate buildings, cities and regions. It is therefore an essential part of an engineer’s skill set to understand and control the risk. Control is a key word, for the risk can never be eliminated, as the recent Grenfell Tower fire in London reminds us. That event was truly a nightmare: an out-of-control fire destroying a whole residential tower, killing 71 occupants. In the same contemporary timeframe, wild fires in California destroyed approx. 9000 structures and left over 40 dead, reminding us of the consequences of regional fires. How these catastrophes happened is yet to be established. It is said that lessons should be learned, and so they should, since the history of fire engineering is largely one of reaction to disasters. As a start, it’s worth observing, as some of the papers in this special issue do, that the basic skills of ‘fire engineering’ are probably absent among many of us. That situation stems partly from an omission of basic training; perhaps from a feeling that this is a speciality for others, and perhaps because advances have been rapid. This is unsatisfactory and unsafe. Fire protection needs to be ensured overall between the architects, plant engineers and structural engineers who make up any project team: we have collective obligations to make buildings ‘safe’.
Heat-induced explosive spalling in fire poses a credible risk to concrete structures, and has received considerable research attention in recent decades. However, no validated guidance to enable the design of concrete mixes to prevent spalling, nor any established, widely verified, repeatable test methods are yet available to confidently quantify or demonstrate spalling resistance for a particular mix in a given application. As a result, no models yet exist that can predict spalling with sufficient confidence to be used in design. This paper summarises contemporary research on heat-induced concrete spalling, with particular emphasis on design for fire of concrete-lined tunnels. The topic is also relevant for modern concrete buildings. A novel, repeatable and economical testing method to reduce project risk by quantifying the propensity of concrete mixes for spalling under a range of different thermal and mechanical conditions is described. The intent of this paper is to present the limitations of knowledge to enable design for heat-induced spalling, and to highlight research currently under way to overcome some of the issues faced in practice.