MEWP access and slab design
Contractor’s regularly require access to the slab, with MEWPs or other work platforms before the floor is in the final condition. These temporary construction loads need to be considered as part of the composite slab design.
Temporary construction and access loads, including MEWPs, should be considered during the preliminary design stage to ensure that there is adequate mesh reinforcement in the slab.
After the concrete is poured the slab should be left undisturbed for long enough (approximately 3 days) for the concrete to gain strength to minimise the risk of damage to the surface. Before the slab is loaded with temporary construction loads, MEWPs etc., the concrete should achieve at least the design strength as specified by the project engineer, verified by cube testing.
There are numerous considerations when designing composite floors for heavy local wheel loads, including but not limited to:
- A dispersion angle of 45° to when calculating effective slab width for bending action – refer BS EN 1994-1-1 (2).
- Check the composite slab bending capacity is sufficient for the wheel loads.
- Check the slab for shear and punching shear exerted by the wheels.
- The worst case should consider the MEWP traveling in all directions to the span
Ensure reinforcement meets the minimum detailing requirement as follows:
Best practise for determining design loads for MEWP’s is to calculate the maximum working load, the sum of the Self Weight and Maximum Working Weight and use 60% of this as the worst-case point load. This accounts for one wheel being overloaded if a basket is at full reach.
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For more information on this topic, see TGN Section 5.4 specifically relating to this topic