Monitoring of steel-concrete bond with the acoustic emission technique
Résumé
Cracking in reinforced concrete structures is of major concern since it may affect their durability and structural integrity. Cracking is mainly influenced by stress distribution along the interface between steel and concrete which is responsible of transferring load from steel bar to the surrounding matrix. Thus, quantitative evaluation of steel-concrete bond effect on fracture properties is important. An experimental investigation on Reinforced Concrete (RC) ties is reported in this paper. Pull-out and tensile tests have been conducted on cubic specimens with high adhesion reinforcement bars with different diameters in parallel with a continuous monitoring using the Acoustic Emission (AE) and the Digital Image Correlation (DIC) techniques. Two failure modes have been observed according to the steel bar section: concrete cover splitting and pull out with damage concentrated near the concrete rebar interface. The results show a good correlation between the loading force and the AE activity with AE signal of different characteristics indicating different active fracture mechanisms. The order of appearance of cracks, their width and their spacing have been also measured in correlation with the loading level for short ties with different lengths and bar diameters.
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