Pile Behavior Established from Model Tests

Eleven one‐tenth scale tubular steel pile tests are conducted to establish the behavior of pinned‐head friction piles in loose sand, fixed‐head friction piles in both loose and compacted sand, and a fixed‐head bearing pile in loose sand. The piles are instrumented with electrical resistance strain gauges and the vertical and horizontal pile movements at grade were measured with displacement transducers. By differentiation and integration of pile strain functions, obtained by curve‐fitting the measured strain data, the soil resistance and displacement relationships are developed in the form of modified Ramberg‐Osgood expressions. The characteristic soil parameters, describing the skin friction and vertical displacement f‐z curves, end‐bearing and settlement p‐z curve, and lateral resistance and displacement p‐y curves, are used in finite element studies that idealized the nonlinear soil behavior by isolated Winkler springs. The analytical results for the pile strains along the embedment length and displacements at the soil surface of a particular pile test correlate reasonably well with the measured values, considering the sensitivity of techniques used to establish the soil responses.