Allan Jowsey

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.

Modelling of the collapse of large multi-storey steel frame structures in fire

Publisher Summary The chapter presents results from a number of non-linear finite element analyses of simple two-dimensional (2D) models of multi-storey structural frames subjected to fire. One of the analyses was carried out for a large range of fire scenarios. The chapter advances that work to include a number of different structural configurations and presents a few more collapse mechanisms. The results of this work are based on very simple 2D analyses, and further computational and experimental research should be carried out to confirm these initial findings, which nonetheless show a clear failure mechanism in multiple floor fires. The chapter presents a selection of results obtained from the simpler 2D models and describes the most interesting failure mechanism. The understanding developed in this manner is of enormous benefit to designers and consulting engineers to understand the true effect of fire in their structures and to ensure that the mechanisms discovered are prevented from occurring with appropriate design and detailing.