Lateral load tests on prestressed concrete piles supporting integral abutments

Four prestressed concrete piles, 14 in. (356 mm) square, were driven 36 ft (11 m) into undisturbed clay soil in a research project sponsored by the Tennessee Department of Transportation (TDOT). Each pile supported a simulated integral abutment 3 ft (0.91 m) thick. The abutment was 10 ft (3.05 m) wide and was cast integrally with an abutment slab which was 2.5 ft (0.76 m) thick. The slab-abutment system was pulled horizontally, displacing the pile laterally and thus inducing moments and shears along a portion of the pile. The abutment slab was restrained against free rotation in a way to simulate the behavior of an abutment in an actual bridge. Each pile was subjected to a number of lateral load tests to a displacement of 1.0 in. (25.4 mm), consistent with TDOT's design criteria, and then were subjected to a number of more stringent tests. One pile was cycled approximately 100 times to a displacement slightly more than 1.0 in. (25.4 mm), and another pile was pulled laterally to failure. The results of the tests clearly indicate that prestressed concrete piles are appropriate for use in integral abutment bridges and that the TDOT design criteria are conservative.