Stresses attributed to traffic loads

Undoubtedly, as the axial loads pass over the rigid slab, stresses are developed. The severity of stresses that developed depends on the position of the wheels (loading point) with respect to the slab. In addition, axle configuration, frequency of loading (intensity of traffic), quality/strength of sub-base and subgrade and Poisson s ratio should also be considered. 

Of these conditions, the stresses produced at the corner (tension at the top) are by far the most severe and hence the most important. Edge loading produces stresses (tension at the bottom) that are slightly less than those caused by corner loading, whilst a load at the interior of the slab generates the least stress (tension (T at the bottom). 

After Westergaard, who in 1948 (Westergaard 1948) also examined the case of elliptical loading surface, other researchers have also investigated the stresses that developed on concrete slabs, such as Pickett (1951), Pickett and Ray (1951), Wang et al. (1972), Shi et al. (1994) and Fwa et al. (1996). 

The detrimental effect of stresses induced by an applied load substantially increases with the loading configuration (other than single wheel load), at rest or during movement. The impact may also be considerable when the adjacent slabs that make up the pavement are non-flushed with each other. To handle this impact, the transverse joints provided have effective load transfer devices such as dowels. 

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