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Détermination expérimentale, au moyen d'un contraintemètre actif, de l'évolution des contraintes dans une poutre mixte acier-BTHP préfléchie

par Staquet, Stéphanie ;Merliot, Érick E.;Van Phu, Cyril N'Guyen;Derkx, François;Toutlemonde, François
Référence Bulletin des laboratoires des ponts et chaussées, 273, page (57-79)
Publication Publié, 2008-12

Article révisé par les pairs

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Résumé :

Validating the behavior of a prebent, innovative steel-very high-performance concrete (VHPC) composite beam requires both a direct identification of the compression reserve provided by the prebending and monitoring of its evolution as a function of the delayed concrete behavior, depending on the loading program imposed upon the structure. For this purpose, a miniaturized prototype stressmeter was developed; the device has been composed of a flat embedded jack whose pressure is being constantly controlled in order to produce a compressive strain identical to that of a reference cross-section. The strains recorded are of good quality and lie within a satisfactory range compared to computation results. Stress variations over a several-hour period are measured with a precision of nearly 0.2 MPa, yet concerns over electrical stability remain critical. After a four-month data acquisition period, the deviation between the absolute value of stress and its estimation by computation equals at most 1 MPa for the composite beam instrumented with the two stressmeters. This precise evaluation of stresses has made it possible to confirm the advantages of using VHPC for this type of composite structure, with a beneficial application of the higher compressive strength and lower delayed strains for this range of concrete.