**Abstract**

Static load tests are seen by many practitioners as the best techniques to approximate in-service conditions for deep foundation elements and to validate analytical model predictions of 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 the resulting data is critical to properly evaluate the test results and recoup the significant investment made in conducting the test. This paper discusses several key points in the interpretation of strain gage data in deep foundation load tests.

**Keywords:** strain gages, deep foundation load testing, tangent stiffness, incremental rigidity, t-z curves
