**1. Introduction**

Static load tests are seen by many practitioners as the premier techniques to approximate in-service conditions for deep foundation elements and to validate analytical model predictions for load-bearing capacity and settlement. Full-scale static load tests are fairly expensive to implement, especially as part of a pre-construction investigation when equipment and personnel must be mobilized to site separately to specifically install the test element(s). Test elements are often instrumented with strain gages to determine the load distribution during the test. Correct installation of gages and interpretation of strain data is critical to properly evaluate the test results and recoup the significant investment made in conducting the test.

The ultimate product of a foundation test strain data analysis is often a set of curves which model the non-linear unit soil response to shear and bearing load (typically called 't-z' and 'q-z' curves, respectively). These curves are useful to model the foundation response to load [1]. Strain gage data is utilized to compute both the shear and bearing ('t') and displacement ('z') portions of the curves.

In the first section, statistical results collected by the author in two large-scale test programs involving multiple test foundations each are analyzed to investigate the optimal positioning of strain gages in a test element. In the second section, the

conversion of strain to force via the rigidity function is discussed. In the third section, use of strain data to properly calculate zone displacement is derived.
