A forum for professionals

The Steel in Fire Forum is a discussion group for those interested in the behaviour of steel framed structures under the influence of fire. BCSA Sustainability Manager John Dowling writes on the forum’s history and its potential.

Organised by the University of Sheffield and funded by the steel construction sector, the Steel in Fire Forum meets twice a year, usually once in Sheffield and once in London. It is a gathering of like minded researchers, specialists and design professionals, all interested in structural fire engineering design methods and dissemination of this knowledge.

The formation of the Steel in Fire Forum can be traced back to the 1980s when British Steel (now Tata Steel) saw the potential for developing alternative means of engineering buildings for fire over and above those described in documents such as Approved Document B (see box, below). It began to understand the positive benefits for the structural steel industry of an improved understanding in this area.

To encourage this, a regular ad-hoc meeting group of interested engineers and fire scientists, from a variety of research organisations, were arranged to facilitate an exchange of information.

Professor Colin Bailey of the University of Manchester has described the manner in which cooperation between researchers took place during the Forum’s early days:  “The early analytical work concentrated on the behaviour of isolated beams and columns. Different theoretical approaches were implemented and the results were compared both with each other and with the available test data at regular group meetings. Initial comparisons were inconsistent, but these improved as the modelling techniques were gradually refined.

In 1995, the nature of these meetings was changed and the Steel in Fire Forum was created in earnest. This was prompted in part by the work associated with the Cardington fire tests, which had begun about that time. These large scale fire tests (see below) demonstrated that composite steel deck buildings had far greater inherent fire resistance than was apparent from standard fire tests. This created an upsurge in interest and research in structural behaviour in fire and it was decided that a more formal forum was required for the exchange of information. Since then it has gone from strength to strength.

It has also gone international and meetings this year will include contributions from Finland, Luxembourg and New Zealand. Details of the agenda and locations can be found on the website www.steelinfire.org.uk and attendance is open to anyone interested in the subject.

The Cardington fire tests were carried out between 1995 and 2003. In order to obtain a direct comparison with the standard fire test, the first test was carried out on a single unprotected beam and surrounding area of slab. The results indicated that a failure deflection would have occurred at a temperature over 1000°C, far greater than the temperature of 700°C at which it would have failed if tested in isolation.

Further tests were carried out in compartments varying in size from 50m2 to 340m2 with fire loadings provided by gas, wooden cribs and standard office furniture. Columns were protected but beams were not. Despite atmosphere temperatures of over 1200°C and temperatures on the unprotected steel beams of 1100°C in the worst case, no structural collapse took place.

Approved Document B is the most widely used source of information on fire precautions in buildings in England & Wales. The equivalent in Scotland is Technical Handbook 2 and in Northern Ireland it is Technical Handbook E. The requirements are prescriptive and fire performance is determined by reference to standard fire tests. However, the document also makes it clear that alternative approaches are also allowed if they can be shown to meet the requirement of the Building Regulations. This opens the door for the engineered solutions which are facilitated by the work of the Steel in Fire Forum.