Innovative Structural Engineering for Tall Buildings in Fire

In response to public demand for safer structures and the commercial drive for robust structural fire design post 9–11, the authors have carried out a number of analyses of the behaviour of long span floor systems including composite cellular beams and composite truss floors similar to the World Trade Centre (WTC) 1 and 2 buildings. The research has considered single and multi-storey fires. For scenarios where fires have been assumed to act over several storeys simultaneously this research is beginning to identify potential global progressive collapse mechanisms in the different long-span floor systems studied. Wherever possible, failure mechanisms are being validated against evidence from the real fires such as those of WTC, Torre Windsor, and others. The research studies so far have provided a substantial increase in the understanding of the whole frame response of high-rise buildings in fire, but the work continues to progress as new structural designs are being analyzed. The intent is that this new understanding will form the basis of design including where appropriate, and always based on a risk assessment, design against structural failure induced by fires. The aim is to propose structural designs that do not rely solely on traditional fire protection measures, but have specific structural detailing that can demonstrate their capability to withstand these events. In other words, they are intrinsically robust rather than totally reliant on added safety measures that can fail in extreme events. This paper will present some of the results of this recent research and show how it is being implemented in design through a case study on a high-rise office building proposed in the UK.