Forensic analysis of fire induced structural failure

Fire investigation has generally focused on the identification of the cause and origin of a fire. Thus methodologies developed for this purpose are mainly based on the dynamics of fire growth and the investigation of its effect on the different objects within the structure affected by the fire. It is unusual to come across a fire investigation emphasizing structural damage as a means to obtain information for fire reconstruction. A series of dramatic fire events such as the Windsor Tower (Spain) and the World Trade Centre (USA) collapses have emphasized the need to introduce a structural analysis alongside the evaluation of the fire timeline. Only the combined analysis is capable of providing a complete reconstruction of such an event and therefore a solid determination of causality. This paper presents a methodology to establish the sequence of events leading to a fire-related structural failure, by means of modern structural and fire analysis tools. This analysis will be compared with classic cause and origin techniques emphasizing the importance of a comprehensive study. Specific structural features and fire conditions that lead to unique forms of failure will be discussed establishing the complexity of linking fire, structural characteristics and failure mode. A series of examples will be used to illustrate different forms of failure and the fires that originate them