Design Assumptions:
1.
Density of Reinforced Concrete = 23.5 kN/m
2.
Live Loads - As per Sentence 9.4.2.3 (1) of the Building Code, the live load is the lesser of the following:
- 1.9 kPa,
- Specified roof snow load, which for Ontario is up to 2.9 kPa. Therefore a specified design load of 3.0 kPa is appropriate; however, the slab specified is capable of carrying higher live loads since the crack control requirements of CSA A23.3 and cover requirements as given below govern the design of the slab.
3.
Design Standards: CSA A23.3-94, “Design of Concrete Structures”.
4.
Exposure and Cover for Reinforcing Steel:
- The slab is considered to be exposed to weather and de-icing chemicals.
- Minimum top cover is 60 mm as per CSA A23.3 Clause A15.1.7.1 plus a 12 mm tolerance on placement.
- Minimum bottom cover is 30 mm as per CSA A23.3 Clause A12.6.2 (slab cast against formwork).
- For 10M reinforcing bars the minimum slab thickness is 72 mm cover + 11.3 mm bar + 11.3 mm bar + 30 mm cover = 125 mm.
5.
Design Assumptions:
- Concrete compressive strength of 32 MPa at 28 days as per Sentence 9.3.1.6.(1) of the Building Code.
- Reinforcing steel yield strength of 400 MPa.
- Slab design is based on a one-way slab simply supported on foundation walls along the edges. Since the slab can be square or rectangular, the same steel is provided in both directions.
- Maximum span is limited to 20 times the slab thickness as per CSA A23.3 Table 9.1.