Experimental study of externally prestressed concrete box-girder beams. Part I: Simply supported beams

Abstract

The paper shows the results obtained in the tests up to failure of 6 box-girder beams with external prestressing carried out in the Structural Engineering Laboratory of the School of Civil Engineering of Barcelona. The beams are simply supported, with 7.20 m span and 0.6 m depth. Three beams are cast in place and the other three are segmentally built with precast elements assembled together through multiple dry (without epoxy resin) shear keys and external prestressing. The different tests are designed with different amount of external prestressing and failure modes (bending or shear). The experimental set-up used enables the continuous monitoring of the most important variables during the tests to failure: deflections, stress increments in reinforcing and prestressing steel, relative slip of tendons at the deviators, joint and crack opening, and ultimate load. The experimental results from the test are compared with the values derived with the theoretical models available. The observed differences between experimental and model results are discussed.