Precast, Prestressed Concrete Bent Caps : Volume 2, Design Recommendations and Design Examples

2018PDFTech ReportFHWA/TX-17/0-6863-R1-Vol2Project 0-6863BentsPrestressed concrete bridgesBridge substructuresBridge piersPrecast concretePretensioned ConcreteBent CapsPier CapsPocket ConnectionInterior VoidShearDesignEnd Region DetailingTexasUnited StatesTexas A&M Transportation InstituteBirely, Anna C.Mander, John B.McKee, Codi D.Lee, Ju DongTexas A&M Transportation InstituteTexas. Dept. of Transportation. Research and Technology Implementation OfficeUnited States. Federal Highway AdministrationUS Transportation CollectionRecommendations for design of pretensioned bent caps are developed based on the findings of full-scale experimental tests of bent cap subassemblages. Companion examples are provided to demonstrate implementation of the design recommendations. First, recommendations are made for converting existing reinforced concrete bent cap designs to pretensioned designs, providing contractors the option to choose pretensioned caps at any point during the construction process. Next, design recommendations are made for the design of pretensioned caps as part of the original substructure design. Flexural design is based on the concept of zero tension under dead load to ensure that any cracks that form close upon removal of live load. Shear design recommendations modify the American Association of State Highway and Transportation Officials sectional design method to ensure that crack angles used are physically admissible. New design recommendations are first demonstrated through examples for standard bridge designs. Additional examples demonstrate use of internal voids to reduce weight and how pretensioned bent caps can be used to eliminate column lines to save construction time and cost. Finally, recommendations and examples are included for end region detailing and for incorporation of a pocket connection that minimizes the effects of prestressing and provides considerable tolerance for construction