STATNAMIC and dynamic load testing of an instrumented drilled shaft at an I-35/I-80 bridge in Des Moines, Iowa

The Iowa Department of Transportation in conjunction with the Federal Highway Administration performed a design. phase Statnamic load test program on a drilled shaft foundation for a series of four new bridges along I-35/I-80 in Des Moines, Iowa. For research purposes, high strain dynamic testing via a drop hammer was also performed. This paper presents the results of Statnamic and high strain dynamic tests conducted at a drilled shaft test site adjacent to the new 2(nd) Avenue Bridge. Load testing was performed on a single instrumented 1.07 meter diameter drilled shaft 27.3 meters in length. The test shaft was designed predominately for side shear in "Glacial Till", gravelly sands and weathered shale. End bearing in the weathered shale was also considered in the design. Internal instrumentation consisted of 12 resistance strain gages and a toe accelerometer which were monitored during Statnamic and dynamic load testing, The paper discusses the results of each test method and their applicability to drilled shaft load testing.