This paper presents a closed-form solution to the problem of a slab-on-grade under combined temperature and wheel loading, derived on the basis of finite element results. This solution is in the form of a multiplication factor (function of the temperature differential) to be applied to the westergaard equation to determine the maximumcombined tensile stress in the slab under edge loading. In addition, a sound, engineering approach to numerical, experimental, and field data interpretation is proposed, founded on the principles of dimensional analysis. In view of the wide variety of available data, including those from the strategic highway research program and from finite element studies, the major problem confronting the profession today is no longer one of data availability, but one of data interpretation. In addressing this problem, the general trend in the last three decades has been to show an overwhelming preference for, and an unlimited confidence in, the results of sophisticated statistical analyses, without much consideration of the underlying engineering interactions among the host of input parameters involved. Although in ahighly empirical field such as the study of pavement behavior regression techniques will always be an invaluable tool, the profession can benefit immensely by using dimensional analysis to determine the engineering dependent and independent variables to be examined. Without such exercise of engineering judgment, regression is lamentably bound to remain just that. This paper appears in transportation research record no. 1227, Rigid and flexible pavement design and analysis: unbound granular materials, tire pressures, backcalculation, and design methods.
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