Meaning
Mathematical equations in pavement design calculate the tensile stress generated at the bottom of a concrete slab by a concentrated wheel load. The Westergaard flexural stress calculation accounts for three critical load positions: the center of the slab, the edge, and the corner. This stress value is compared against the flexural strength of the concrete to determine if the slab will crack under the design loads.
Formula Application
The calculations utilize the modulus of subgrade reaction, the thickness of the slab, and the magnitude of the wheel load. This approach assumes the concrete behaves as a thin elastic plate supported by a dense liquid foundation. The resulting stress value helps engineers select the appropriate concrete thickness and reinforcement.
Adjusting the load contact area allows for more accurate representations of dual-wheel assemblies.
Load Case
The edge and corner load cases generate the highest flexural stresses in the concrete because the slab is least supported at these locations. This is why pavement joint design is so critical for the long-term performance of the floor. Designing for the center load case alone leads to under-designed slabs that crack prematurely.
Design Consequence
Using these equations ensures that the floor can withstand decades of repetitive vehicle traffic without experiencing structural failure. This mathematical approach is the standard for both industrial warehouses and airport runways. It provides a reliable basis for material specifications.
