Behavior of Pile Supported Integral Abutments

Two sets of field tests on integral abutments were preformed at the University of Tennessee in research sponsored by the Tennessee Department of Transportation (TDOT). Tests on concrete abutments supported by steel H-piles were followed by tests on prestressed concrete piles. The purpose of the tests was to evaluate the design criteria used by TDOT to design integral abutment bridges. The nation’s leader in the utilization of integral bridges, TDOT continues to extend the length limits of such bridges. The research described here provided realistic field data upon which to evaluate design criteria. Piles were driven into residual red clay soil. Concrete abutments were built on top of the piles to simulate the behavior of actual integral abutments. Lateral load was applied to the piles to induce horizontal displacements consistent with those that occur due to temperature change. Six abutments with steel piles and four with concrete piles were tested, first to the displacement limits corresponding to TDOT criteria, and then to displacements well beyond the current design limits. Tests to failure of two abutments with steel piles and one with concrete piles are particularly interesting. The test results showed that current TDOT design criteria for maximum horizontal displacement are conservative. The test data indicated that current criteria could be extended to accommodate somewhat larger displacements and correspondingly longer lengths for jointless bridges.