Bonopera MChang K.-C.KUO-CHUN CHANG2022-03-222022-03-22202113694332https://www.scopus.com/inward/record.uri?eid=2-s2.0-85110087127&doi=10.1177%2f13694332211022067&partnerID=40&md5=28e04725f9d2c7061e0e10052e1017echttps://scholars.lib.ntu.edu.tw/handle/123456789/598542Testing methods are required for estimating prestress losses in Prestressed Concrete (PC) girder-bridges. They mainly include destructive approaches which cause significant damages. Conversely, dynamic nondestructive methods are unsuitable. Given these findings, a novel method for identifying residual prestress force in simply supported PC girder-bridges was implemented. Following the vertical load application in a three-point bending, the method estimates the prestress force by measuring the vertical deflection at a quarter or, alternatively, at the midspan of the PC girder-bridge. The method also requires information regarding its flexural rigidity. Particularly, the initial tangent Young’s modulus must be evaluated by compression tests on cores drilled at its quarter and midspan cross-sections after three-point bending. In absence of the geometric and/or material properties, the flexural rigidity can be estimated according to free vibrations. Secondly, the method comprises a reference solution, or a finite element model of the PC girder-bridge, in which the prestress force is unknown. Thirdly, the measured deflection becomes a parameter of the prestress force identification process. Accurate identifications are obtained when the deflection, under a higher vertical load, was precisely measured and the flexural rigidity was determined using reference solution and initial tangent Young’s modulus. In this article, the novel method was simulated on a simply supported PC beam-bridge subjected to time-dependent prestress losses for ?9.5 months in the laboratory. ? The Author(s) 2021.Concrete beam-bridgeflexural rigidityprestress force identificationthree-point bendingvertical deflectionBending diesBending testsCompression testingPrestressed beams and girdersPrestressed concreteRigidityFlexural rigiditiesNondestructive methodsPrestress forcesReference solutionResidual prestressSimply supportedThree point bendingVertical deflectionsConcrete beams and girders[SDGs]SDG11journal article10.1177/136943322110220672-s2.0-85110087127