"SABS 0100 compliant"
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The tables are calculated in accordance with SABS 0100 and the load-factors of SABS 0160. (i.e. load factors for dead load and live load are 1.2 and 1.6. Factors for service conditions are 1.1 for dead load, and 1.0 for live load). Figures in the tables are service applied load in kPa.

It is assumed that a good quality concrete, with a long term Young's Modulus of 28 x 10 E 6 MPa is used. (See 'Properties of aggregates in Concrete' published by Hippo Quarries). If concrete with a lower Young's Modulus is used, deflections will increase and should be checked.

It is emphasized that the prestressing of the ribs is to facilitate handling during transport and erection. The ultimate design strength of the slab, according to SABS 0100, ignores the effect of prestressing. Therefore, the wire in the prestressed ribs are considered as tension reinforcement with a yield stress of 1700 MPa. The initial stress at release is 70% of Ultimate. The width of the section is a shown in the technical specifications. Shear connectors (4,5mm ø) are provided at 600mm centers along ribs.
 
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Mesh is provided in the topping as anti-crack reinforcement and under normal circumstances provides no structural strength. In addition, where the slab is continuous over supports, additional top steel should be provided for one fifth of the span each side of the support. The amount should not be less than 0.3% of the rib area.

For designers who wish to perform their own calculations, the essential properties of the sections are tabulated above each table.

These are:

  1. The uncracked Moment of Inertia in m4/m.
  2. The Ultimate moment of resistance, (Mu) in kNm/m.
  3. The ultimate shear strength (Vu) in kN/m.
  4. The self weight of the section in kN/m² (assuming a unit weight of 24 kN/m³ for concrete).

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