PRESENTATION OF THE FIRST RESULTS OF THE EXPERIMENTATION OF THE CLERVAL VIPP BEAM

Abstract

The territorial Division for the Central-Eastern Regions(DterCE) of Cerema in France has set up an experimentalproject about a 30 m prestressed concrete bridge girderrecovered during the demolition of a bridge. This project aims to – improve the technical and auscultation materials, methods ofinterpretation, modeling tools and calculation of “IndependentViaducts and span precast prestressed beams”, essential tocarry out a relevant reassessment of their performance.– obtain a better understanding of the mechanical behavior ofstructures reinforced with bonded FRP by offering suitablejustification methods.Other Divisions of Cerema, IFSTTAR thanks to theirspecializations measurements on structures were also involved inthis project. In mid-April 2014, the beam was transported to theloading platform to submit it to 3 points bending load tests withover 200 sensors. Before testing, a accurate diagnosis of thebeam has been achieved.Three series of tests were carried out in 2014:– A first series of tests “cracking” before reinforcement,– A second series of tests “cracking” after a first phase ofreinforcement bonded composite materials,– A third series of tests “cracking” after a second and final phaseof reinforcement bonded composite materials. This final testwas gradually led to a complete rupture of the beam.This first unique experience on a VIPP beam reinforced withFRP allows us to deliver some first lessons:– The real failure of the beam was held to a force of about 61– The real failure of the beam was held to a force of about 61tonnes (vertical displacement at mid-span = 20 cm).Thereafter, the effort has been decreasing.– The complete failure by delamination of the bonded compositereinforcements (which have thus accompanied the beam tomaximum effort of loading), was held to a force of about59tonnes (vertical displacement at mid-span = 27 cm).– The complete failure in bending in a controlled section wasobtained (vertical displacement at mid-span more than40cm).The maximum stresses that have been recorded in the materialsare following orders of magnitude:– Compression of the concrete: more than 65 MPa recorded bythe optical fibers;– Overstrains in prestressing cable: more than 600 MParecorded by local deformation gauges;– Tensile stresses of the FRP reinforcement (measured at bondinginterfaces): more than 900 MPa recorded by the optical.For information, the technical characteristics of used FRPprocess sets the tensile stress limit for the SLS calculation of thecomposite at 500 MPa.