FIRE SAFETY OF OPEN CAR PARKS IN STEEL

The existing fire safety requirements of open car parks are not the sa me for all European countries. For example, an unprotected steel struc ture is allowed in Germany, whereas in France, an ISO-fire resistance of 90 minutes is required. In order to clear up these differences, the Technical Working Group 3.3 from ECCS produced the Technical Note 75 which provides a complete study of the behaviour of open car parks in case of fire (1). The note is based on information and test results av ailable throughout the world. Two surveys of the fire experience in ca r parks made in USA and Canada (2 to 5) and one in Switzerland (6) lea d all to the same conclusion: <<there is extremely low fire hazard in car parks, and in case of fire, the building damage reported are very small>>. The fire tests already performed in Australia, USA, Japan and United Kingdom show that unprotected steel structures are fire safe, the maximum measured steel temperature being beneath 360-degrees-C. Ad ditional tests were also carried out in the Fire Technology Laboratory of the Technical Research Centre of Finland (VTT) (7). During these t ests, the rates of heat released by the burning cars were measured and a <<Car fire model>> was deduced. This model combined to the air temp erature calculation methods (ceiling jet flow, zone model, fluid dynam ic program), allowed to obtain the air temperature field around the st ructure. The temperatures inside the sections and the structural behav iour during the fire were analysed using advance thermo-mechanical sof twares (CEFICOSS, TASEF and SISMEF). These numerical simulations point ed out that no failure of the unprotected steel structure will occur, provided that the sections of the beams have a composite behaviour (st eel profile connected to the concrete slab). In short, the engineering work presented in this document shows that unprotected steel structur es used for open car parks are fire safe and even reparable.