Experimental Behavior of Reinforced Concrete and Pretensioned Concrete Bent Caps

Abstract

Accelerated bridge construction using precast bridge substructures can enable reduction of traffic disruption, increased worker safety, and increased quality through controlled conditions at the time of fabrication. A largely unrealized benefit of precast substructures is the use of pretensioned bent caps that can provide superior performance to that of reinforced concrete bent caps. Full-scale experimental tests of reinforced concrete (RC) and pretensioned, prestressed concrete (PSC) bent cap subassemblies were conducted to verify the improved performance of pretensioned caps. Flexural reinforcing bars and strands were distributed along the sides of the bent cap to accommodate a pocket connection designed to provide large construction tolerances. Results showed superior performance of the pretensioned cap, including delayed initial cracking, smaller average flexure crack widths, and absence of shear cracking. Removal of live loads resulted in full closure of cracks, validating the design philosophy of zero tension under dead load.