International audienceThe article aims at detecting and quantifying early structural damages usingdeterministic and probabilistic model updating techniques. To achieve this purpose,local information in a form of optical strain measurement is employed. Thestrategy consists in updating physical parameters associated to damages, suchas Young’s modulus, in order to minimize the gap between the numerical strainobtained from finite element solves and the strain sensor outputs. Generally,the damage estimation is an ill-posed inverse problem, and hence requires regularization.Herein, three model updating techniques are considered involvingdifferent type of regularization: classical Tikhonov regularization, ConstitutiveRelation Error based updating method and Bayesian approach.An illustration of these three approaches is proposed for localizing and quantifyingan early damage in a real 8 meter post-tensioned concrete beam. Numericalresults show that all the methods properly localize the damaged areaand give similar estimation of the damage leve
Influence of the bituminous layer on temperature and water infiltration in railway structures of the Bretagne -Pays de la Loire high-speed line.The phenomena of settlement and wear of the ballast under dynamic stresses lead to high frequencies and high maintenance costs on high speed railway lines.Studies have shown that these settlements are linked to high accelerations produced in the ballast by the passage of high-speed trains (HST). A layer of asphalt concrete (GB) was introduced under the ballast layer on the high-speed line Bretagne-Pays de Loire (BPL HSL). It is intended, among other things, to reduce the amplitude of accelerations produced at the passage of the HST, and thus improve the durability of the track.The BPL HSL spans 105 km with a sub-layer of asphalt concrete under the ballast, and 77 km with a granular sublayer (UGM). To evaluate the performance of the structures with bituminous sublayer, and to compare it with traditional structures, with granular sublayer, 4 track sections have been instrumented during construction. This article presents the different sensors of the instrumentation as well as the acquisition system installed to collect measurements. The focus, in this study, concerns the temperature, water content and vertical settlement measurements made on the instrumented sections. Temperature variations recorded during two years on the railway structure with bituminous sublayer were analysed and compared to those measured on a classical bituminous pavement.Influence of the bituminous layer on water infiltration and track settlements has also been studied.
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