Experimental research on seismic performances of prestressed high-strength concrete pipe piles and pile-pile cap connections

Based on the results of six prestressed high-strength concrete pipe piles and pile-pile cap connections under cyclic loading, the failure patterns and the mechanism of the specimens are described. The stresses of piles, strains of anchor bars, hysteretic performances and bearing capacities of different connections are analyzed. It is shown that the specimens appear to be flexural failure from the test results. There are two kinds of failure modes observed in the tests: the failure is sudden and brittle because of the fracture of prestressing tendon, and the connections are severely damaged because of the yielding of anchor bars and appearing of the plastic hinge. In addition, the bearing capacities and hysteretic performances increase with the rotation capacity of pile connections.