Abstract
The behaviour of composite steel structures during fire is a fundamental criterion for the
global stability and durability of these structures. Following several fire disasters, the
assessment of structures stability and behaviour of individual elements have been the focus of
many research projects in fire safety over the last two decades. Full scale experimental works
and finite element modelling developed by Sanad et al. were carried to understand the effect
of fire on composite buildings. In full scale buildings, slabs, beams and col umns behave in
different ways and depend on the strength, duration and variation of heating regime with time
and space. Recent researches showed that the behaviour of indeterminate beams under fire is
dominated by thermal expansion and changes drastically from its behaviour under ambient
condition. However, in composite structures, the reinforced concrete slab acts together with
steel beams to provide the needed bending capacity for carrying the applied loads. During real
fire, the different conductivity of concrete and steel creates huge difference of temperature
between the two elements. Their behaviour at high temperature varies from ambient
conditions and the role of composite action in transferring the applied loads changes
accordingly. In this paper, a numerical model for composite floor during fire is developed
using finite element program ABAQUS. It is validated against full scale fire test, with the
ultimate objective of investigating the behaviour and contribution of steel beam and concrete
slab to the global stability of the composite structure during fire. Both the obtained numerical
and experimental results are in good agreement and the model proposed in this paper can
predict with acceptable accuracy the global behaviour of the structure under fire.