Experimental and Numerical Investigations of Steel and Concrete Composite Floors Subjected to ISO Fire Condition

Abstract

The very positive membrane action of steel and concrete composite floor systems (concrete slabs connected to steel beams by means of headed studs) has been clearly demonstrated through various Cardington real fire tests. However, little evidence is established for fire performance of such structural system exposed to ISO fire condition, the lack of which still constitutes an obstacle for certain national authorities to accept totally the application of the design concept derived from above real fire tests, in particular for long duration ISO fire.On the basis of the above situation and in order to enlarge the application of the design concept based on membrane action to all types of fire, CTICM, within the scope of two different research projects FRACOF and COSSFIRE, performed successively two full scale ISO fire tests, both of which lasted for more than 120 minutes, with two different steel and concrete composite floor systems designed according to Eurocode. The observed fire performance of these floor systems during the tests was extremely satisfactory and revealed a solid robustness of such type of structure systems in fire situation. Considering the fact that the fire test of FRACOF project has been already presented in detail during SiF'08 and Eurosteel2008 conferences, this paper is focused especially on the comparison of above two tests with regard to structural configuration, loading condition, structural behaviour and failure modes.In addition, these tests have been subjected to a specific numerical investigation with help of a 3D hybrid structural FE model. It is illustrated through this numerical investigation that the actual advanced modelling technique is accurate enough to reproduce precisely the fire behaviour of complex structural systems and may be applied to fire safety engineering with high level of confidence.

Fire resilience of a steel-concrete composite floor system :

“…These findings led to the development of simplified desktop design methods (Bailey 2000;2001;2003) accounting for tensile membrane action of composite floor assemblies at elevated temperatures. Both FRACOF (Zhao et al 2008) and COSSFIRE projects (Zhao et al 2011) further examined the benefit from Bailey's method by conducting standard fire tests on large-scale composite floor assemblies.…”

Results and analysis of a large-scale fire test on a multi-bay composite steel-frame floor system

“…Other large-scale fire tests conducted since that time have included two tests by CTICM and ArcelorMittal, known as the FRACOF test and the COSSFIRE test (Zhao and Roosebid, 2010). The FRACOF test structure measured 6.7 × 8.7 m and incorporated four columns surrounding one bay.…”

Design issues of thermal induced effects and temperature dependent material properties in Abaqus

“…The temperature gradient necessary for the input of numerical model is the value of x obtained by solving equation (7). The two values obtained for the discussed cases are 2 and 1.42857 respectively.…”

“…Examples can be found in literature for validation of dedicated software [5,6] as well as for general purpose finite element codes [7]. While the first category includes most of the material properties and settings for the numerical models, the latter require additional information for environment definition.…”