Role de l'enrobage de beton et effet des fibres metalliques sur le comportement des poteaux en beton confine a haute performance.

摘要

This report presents an experimental study on the action of the concrete cover and the effect of steel fibres on the behaviour of 16 large-scale columns under concentric loading. The specimens were built with high-strength concrete (HSC), ranging from 60 to 120 MPa, and highly confined by rectangular ties. The variables under study were the presence of a concrete cover, the height of the specimens, the presence of supports to hold the concrete cover, and the amount of steel fibres in the concrete mix.;It is possible to prevent the concrete cover from buckling by adding to the concrete mix a volumetric amount of steel fibres as small as 0.25%. The results have shown that, for the three volumetric amounts of steel fibres tested (0.25, 0.50 et 1.0%), the failure stress of the concrete cover is higher than the theoretical expected stress (0.85 ;The confinement model developed by Cusson (1993a) is not accurate for the prediction of the behaviour of high-strength fibre-reinforced concrete columns. From the six fibre-reinforced columns tested, modifications to the original model are proposed. However, because of the small number of high-strength fibre-reinforced concrete specimens tested, this study represents only a starting point in the prediction of the behaviour of these types of columns. (Abstract shortened by UMI.).