5.1 - Reinforcement
Composite slabs require mesh reinforcement in the top of the slab to provide crack control, transverse load distribution and nominal slab continuity in accordance with BS EN 1994-1-1 clauses 7.4.1(4), 9.4.3(5) & (6) and 9.8.1(2) or BS5950-4 clauses 6.7, 6.8 and 6.9 – the minimum requirements and comparison of the different design codes is shown in table 5.1a. This reinforcement is usually in the form of welded steel fabric (mesh) in accordance with BS4483. Alternatively, in some design cases the steel fibre reinforced TAB-Deck™ solution, from ArcelorMittal Sheffield, can be used.
For Technical information on the TAB- Deck™ solution and benefits of this form of construction refer Section 13.4 of this document or contact ArcelorMittal Sheffield.
Refer to SMD.PRO.121 - SMD Fibre Reinforced Concrete Slabs Design Guide
In many cases, the reinforcement provided for the composite stage may be suitable to achieve the required fire resistance. This must be checked against the load/span tables for the specified design criteria (deck profile, gauge, slab depth and concrete type/grade). Where designs are outside the scope of the design tables provided, additional bottom reinforcement may be required for fire.
For some composite slab designs, reinforcement in addition to that associated with the composite action of the deck and concrete will be required (i.e. cantilevers, void trimming, composite beam transverse reinforcement, building regulation compliance or enhanced crack-control due to sensitive finishes). The design and specification of any additional or increase in reinforcement is the responsibility of others, typically the project structural engineer.
When specifying reinforcement mesh sizes, it is important to consider the concrete cover over the profile to allow for lapping of sheets of mesh with nesting where appropriate. Typically the concrete cover over the profile can be as little as 60mm. Where this is the case, the use of mesh reinforcement with flying ends may be necessary to enable the top cover dimension to the mesh to be achieved.
The detailing of all reinforcement within the composite slab is the responsibility of the slab designer.
Although cracks do not normally pose a durability or serviceability hazard, there are instances where the composite floor slab is required to provide a wearing surface or receives applied finishes that may be sensitive to cracking. Reinforcement percentages in excess of 0.3% are likely to be required to limit crack widths to an acceptable level.
Refer to SMD Elements ® design software
Refer to Eurocode NCCI PN005c-GB or more information
Refer to SCI Publication P-056 (BS5950 Design) or more information
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