Investigation and development of an effective, economical and efficient concrete pile splice.

PDFTech ReportBDU79Piles (Supports)Precast concreteSplicingStructural connectionBending stressPosttensioningLaboratory testsFloridaFlorida. Dept. of TransportationMullins, GraySen, RajanUniversity of South Florida. Dept. of Civil and Environmental EngineeringUS Transportation CollectionStructures such as bridges or tall buildings often require deep foundations in order to reach soil or rock strata capable of resisting the associated high loads. In Florida, concrete elements such as driven piles, drilled shafts or other cast-in-place alternatives provide a natural choice. This is somewhat in response to the economy of concrete in Florida, but for marine structures, concrete provides excellent durability via the concrete cover that protects the reinforcing steel. In some cases, however, bearing layers are too deep for precast piles due to limitations on trucking lengths and lifting weights. In such applications, drilled shafts have an advantage, but drilled shafts are not well-suited for all soil conditions. As a result, longer precast concrete piles must be spliced from shorter, more easily transported segments. Historically, these splices have presented problems.The most successful and robust concrete pile splices have been mechanical splices that cast into the ends of the piles some form of steel connection detail where a key, bolts, or pins fasten the two segments together in a fashion more aligned with structural steel connections. These connections, while effective, must transfer tension stresses during driving from one pile segment to the next via reinforced concrete concepts (i.e. development length of large rebar cast into the ends of each pile segment). As a result, prudent state specifications restrict tension stresses to less than half that allowed an unspliced prestress pile. This study investigated the use of an alternative approach that incorporated post tensioning pile segments together to form a splice. The concept eliminates the limitations on tension stresses during driving.This report presents the findings from numerical modeling, laboratory testing, full scale bending tests, and a driving demonstration of prestressed concrete piles spliced using the developed concept