360R-06 Design of Slabs-on-Ground

DESIGN OF SLABS-ON-GROUND 360R-31
0.8 MPa) for steel-cord tires, and 180 to 250 psi (1.2 to 1.7
MPa) for solid or cushion tires (Goodyear Tire and Rubber
Co. 1983). Some polyurethane tire pressures exceeding
1000 psi (6.9 MPa) have been measured. Large wheels have tire
pressures ranging from 50 to 90 psi (0.3 to 0.6 MPa). 
Appendix l
shows use of the PCA design charts for wheel loadings.
6.2.1.2 Concentrated loads—Concentrated loads can be
more severe than wheel loads. Generally, flexure controls
the concrete slab thickness. Bearing stresses and shear stresses
at the bearing plates should also be checked. Design for
concentrated loads is the same as for wheel loads. Also, the
proximity of rack posts to joints should be considered. 
Section
A1.3 
shows the PCA design charts used for concentrated loads
as found in conventionally spaced rack and post storage.
6.2.1.3 Uniform loads—Uniform loads do not stress the
concrete slab as highly as concentrated loads. The two main
design objectives are to prevent top cracks in the unloaded
aisles and to avoid excessive settlement due to consolidation
of the subgrade. The top cracks are caused by tension in the
top of the slab and depend largely on slab thickness, load
placement, and short- and long-term subgrade deflections.
The PCA tables for uniform loads (
Appendix l
) are based on
the work of Hetenyi (1946), considering the flexural strength
of the concrete and the subgrade modulus as the main vari-
ables. Values other than the flexural strength and subgrade
modulus are assumed in the tables.
6.2.1.4 Construction loads—The PCA method does not
directly address construction loading. If, however, such
loading can be determined as equivalent wheel loads,
concentrated loads, or uniform loads, the same charts and
tables can be used.

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