PRESTRESSED CONCRETE BEAMS WITH ARTIFICIALLY DAMAGED STRANDS: PLAN OF EXPERIMENTAL TESTS AND NUMERICAL MODELING

This paper presents the plan of the tests and some preliminary results of a new experimental structural health monitoring (SHM) campaign on prestressed concrete (PC) beams with artificially damaged prestressing strands. Twelve PC beams have been designed and manufactured in the context of a wide research programme at the structural laboratory of the University of Messina, Italy. Specimen dimensions and boundary conditions are selected to be representative of a scaled bridge girder. To this aim, the main girder is simply supported, a superimposed dead load has been added, and a transversal steel beam has been introduced in the experimental setup across the mid-span of the main girder to reproduce the loading scenario in a real 4-girder bridge grillage scheme, including the effect of the transverse diaphragm. The SHM tests are aimed at analyzing both serviceability and ultimate load conditions of these PC girders under different damage scenarios. Indeed, the beams are manufactured with small holes in their bottom face, so as to allow the cutting of prestressing strands to artificially simulate the corrosion at different locations. Modal identification through operational modal analysis (OMA) techniques has been planned for various load levels and damage scenarios (different locations and amounts of strands’ cuts). The experimental tests have been complemented by a finite element model (FEM) including nonlinear behavior through fiber hinges and staged construction to reproduce the various phases of the experimental campaign. The validity of this FEM simulation has been demonstrated by means of comparison with previously tested PC beams with two different prestressing levels and is supported by the good agreement with preliminary results obtained in the first phases of this ongoing experimental activity.