This paper presents a three-dimensional photoelastic investigation of two- and four-pile caps for different depth—pile spacing ratios. For the analysis, the pile caps were idealized as rectangular blocks subjected to patches of loading at the column and pile locations. The individual stress components, their maximum values and locations were determined. Graphs showing the variations of important normal and shear stress components across depth, non-dimensionalized with the applied column stress, were given. On the basis of the results obtained it is concluded that the factors which are not hitherto considered in the design of pile caps have a significant bearing on the stress distribution.
