Seismic Performance of Pretensioned Centrifugal Spun Concrete Piles with Combined Steel Strands and Deformed Steel Bars

Pretensioned spun high-strength concrete piles usually use the traditional helical grooved steel bars as the main reinforcement, leading to insufficient ductility. Replacing prestressing steel bars with steel strands can effectively overcome the problem. To further enhance the overall seismic performance of the piles, pretensioned centrifugal spun concrete piles with combined use of pretensioned steel strands and nonprestressing deformed steel bars (PSRC piles) have been developed. This paper presents experimental and numerical investigations into the seismic performances of PSRC piles. Three full-scale PSRC pile specimens have been tested under lateral cyclic loading with different axial compressive forces, and the results are analyzed in detail and discussed. The influence of incorporating the deformed steel bars on the cyclic behavior of piles is examined with a comparison to the previous test results of the counterpart piles with only steel strands. A detailed finite element model of the PSRC pile specimens is developed and verified against the test results. Parametric analyses are then carried out using the validated model. The results show that the incorporation of nonprestressing deformed steel bars markedly improves the cracking behavior of the piles with much-diffused crack distributions. The combined use of steel strands and deformed bars also results in better deformation capacity as well as higher load-bearing capacity. By adjusting the concrete wall thickness and selecting a desirable ratio of prestressing steel strands and nonprestressing deformed bars, sufficient deformation and load-bearing capacities can be ensured with the piles.