In 1996 we encountered pile integrity problems on two projects. As seen in the figure, the spiral reinforcement and prestressing tendons were cast with major eccentricity in these 14-inch-square PCPS concrete piles. On the two separate projects the piles were cast by a different one of our two local casting yards. Poor quality control was an "equal opportunity" issue, unfortunately. This 130-ft-long single-piece pile broke near midspan in picking it up for installation.

These types of problems occur most frequently in piles on the order of 100 ft or more in length, suggesting that the steel elements are sagging in the middle over these lengths. Without breaking a pile at mid span for inspection, the most obvious field observation is severe bowing of the pile in the leads, with the top side of the pile (as cast) bowing outward. A careful piledriver often succeeds in accomodating defects of this kind, such that the wisdom suggests that if he/she can get it into the ground it has seen the worst loading it will experience during its service life. Unfortunately, in "earthquake country" the flexural loading of the pile section in the ground may deliver service loads that such a vulnerable as-built pile may not tolerate.

Good quality control in the casting yard (appropriate centralizing elements) diligently installed in the beds, should easily remedy such problems. As usual, we always recommend that the piles be driven no sooner than 14 days after casting to avoid limited concrete toughness problems. Had the pile shown here been 12 months old, it probably would have been handled and driven without any problems.