Conclusions drawn from laboratory tests, analytical studies, and observations of piling during earthquakes indicate that when soils undergo cyclic movement, embedded piles are bent into curvatures of various radii. The magnitude of these curvatures can be estimated by studying acceleration-time history response of the specific soil profile. Piling can then be designed to develop the induced curvatures by using smaller and more flexible cross sections and by increasing the percentage of spiral confinement reinforcing. The pile bending problem is one of geometry and ductility rather than moment capacity. I view of recent proposed code changing restricting to use of prestressed concrete piling in the United States, several testing programs are being contemplated to verify prestressed concrete's ability to develop the required strength of the pile cap embedment and ductility at the pile/pile cap interface. The proposed tests would also further verify the design and detailing requirements for induced curvatures at a specified depth. This article provides interim design provisions for the design of prestressed concrete piling pending further testing analysis.
