Abstract
This investigation is related with the fire resistance of composite slabs with steel deck. This composite solution consists of a concrete topping cast on the top of a steel deck. The concrete is typically reinforced with a steel mesh and may also contain individual rebars. The deck also acts as reinforcement and may be exposed to accidental fire conditions from the bottom. This composite solution is widely used in every type of buildings and requires fire resistance, in accordance to regulations. The fire resistance is specified by the loadbearing capacity (R), insulation (I) and integrity (E). The fire rating for (R) and (E) is not in the scope of this investigation. The fire rating for insulation (I) is evaluated by two different methods (numerical simulation and simple calculation). The fire rating is calculated for 32 different geometric configuration, in order to evaluate the effect of the thickness of the concrete layer and the thickness of steel deck. The fire resistance (I) increases with the thickness of the concrete when using both methods, but the simple calculation method seems to be unsafe for all the cases, requiring a revision for the formulae presented in Annex D of EN1994-1-2. A new proposal is presented.
Highlights
Concrete slabs with steel decks are slabs that use steel deck as a permanent formwork and as reinforcement to the concrete placed on top, see Figure 1
The composite floor is usually made with these plate elements supported by secondary beams and shear studs that are responsible for the composite action between both elements
The fire resistance of both elements is prescribed by the building codes, but this investigation only considers the fire behaviour of the plate element
Summary
Concrete slabs with steel decks are slabs that use steel deck as a permanent formwork and as reinforcement to the concrete placed on top, see Figure 1. In 1999 Bailey et al [3] presented the results of 2 experimental full-scale tests (complete building), demonstrating that the performance of the structure under fire differed from that was expected from fire codes and demonstrated that they were conservative. Both tests demonstrated that the element behaviour is different from what is normally obtained from standard small-scale fire tests. More recently in 2017, Guo-Qiang Li et al [5], performed 4 tests in composite slabs with steel decking, which were fire rated with 90 minutes and concluded that Eurocode 4 design calculations are conservative and that could be used for the other geometries, beyond the specified limit. This research presents summary of previous experiments developed on composite floor systems
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