Your coverage of the NIST report on the Twin Towers (NCE 30 June) mixed excellent factual reporting of the recommendations with some creative interpretation.
In particular the statement:'No further use of performance based fire design until more research is completed' is nowhere to be found in the text of the report or the recommendations. Indeed the whole tenor of the recommendations is strongly supportive of performance based approaches to fire engineering design.
Such approaches provide a much better understanding of how real fires behave and how real structures behave in fire; therefore they give a much clearer indication of real safety levels than traditional prescriptive methods.
While performance based design can result in significant economies in the use of fire protection, it also allows designers to provide enhanced robustness in buildings that require it. The principle is to put protection where it is needed. This can mean increasing protection in particularly sensitive areas.
Professor Ian Burgess and Professor Roger Plank, University of Sheffield, Professor Jose Torero, University of Edinburgh, Dr Barbara Lane, Arup Fire, Gerald Newman, Steel Construction Institute.
John Dowling, Corus Construction & Industrial Editor's note: NIST's Recommendation 9 refers to the development of performance based standards, backed up by, among others, new software and test methods. Developing reliable test methods will require research. NIST clearly states that these test methods are an essential requirement for the introduction of performance based standards, therefore, until the research is completed and the new tests developed, performance based standards can not be finalised.