Recently, a large size composite pile composed of steel pipe and PHC pile was introduced into the market: pile diameter is equal to or larger than 1,000mm. A steel pile is placed in the upper part to support lateral loads and a PHC pile is placed in the lower part to resist axial load mainly. A mechanical joint is applied at the interface of the two different materials. This could be more favored to conventional welding method in terms of cost and time in construction.
A two-point bending test procedure was used to simulate the response of a pile subjected to lateral loads. The load-deformation response, crack growth on the surface of pile, ultimate bearing moment capacity and mode of failure were evaluated. The test results showed that the mechanical joint could provide a sufficient resistance to lateral load and bending moment when it was used for a composite pile.
Field tests including static load tests, dynamic load tests, lateral load tests are comprehensively performed to evaluate the behavior of non-welded steel-PHC composite piles which have outer diameter of 1000mm at a soft deposit area near the South Sea of Korea. The soft deposit (alluvium), has 20m thick from the top of the ground surface and mainly consists of silt and silty-sand. Load transfer behavior, axial and lateral bearing capacities of piles are analyzed based on field test results. And the design criteria are suggested to help predict the behavior of the pile and ensure pile stability.