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The evaluation of the ductility of reinforced concrete beams is very important, since it is essential to avoid a fragile collapse of the structure by ensuring adequate deformation at the ultimate limit state. One of the procedures used to quantify ductility is based on deformations, namely, the plastic rotation capacity. Knowledge of the plastic rotation capacity of certain regions of the structure is important for a plastic analysis or a linear analysis with moment redistribution. An experimental program is described in this article. It is composed of 10 tests designed to study the moment redistribution and ductility of continuous high-strength concrete beams. Particular care was given to analysing how the tensile reinforcement ratio and the transverse reinforcement ratio influence the plastic rotation capacity of the beams. A comparative study was carried out on several codes related to the moment redistribution permitted and the experimental findings. It was found that some of the recommendations are unsafe. It was also found that high-strength concrete beams, when properly designed, have enough deformation capacity to be used in plastic analysis.Résumé : L'évaluation de la ductilité de poutres en béton armé est très importante, puisque cette donnée est essentielle afin d'éviter un effondrement fragile de la structure en assurant une déformation adéquate à l'état-limite ultime. L'une des procédures utilisées pour quantifier la ductilité est basée sur les déformations, notamment la capacité de rotation plastique. Il faut connaître la capacité de rotation plastique de certaines parties de la structure afin de pouvoir effectuer une analyse plastique ou une analyse linéaire avec une redistribution des moments. Cet article décrit un programme expérimental. Il comprend 10 essais conçus pour étudier la redistribution des moments et la ductilité de poutres de béton continues à haute résistance. Une attention particulière a été portée à analyser comment le rapport d'armatures en tension et le rapport d'armatures transverses influencent la capacité de rotation plastique des poutres. Une étude comparative de plusieurs codes a été effectuée quant à la redistribution des moments permise et aux résultats expérimen-taux. Il a été trouvé que quelques-unes des recommandations étaient non sécuritaires. Il a aussi été trouvé que lorsque les poutres de béton à haute résistance sont bien conçues, leur capacité de déformation peut être utilisée dans l'analyse plastique.

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h i g h l i g h t sMethod to assess steel strains inside concrete members using surface measurements. This approach has non-contact and does not interfere with the bond between steel and concrete. Validation using concrete ties monitored using strain gauges placed inside the steel bars. The technique can be applied to narrow regions, surrounding a single crack, or to larger regions. Results proved the feasibility of the method. a b s t r a c tThe measurement of steel strains in reinforced concrete structures is often critical to characterise the stresses along the member. In this scope, this manuscript describes the development of a method to assess steel strains inside concrete members using solely surface measurements. These measurements were obtained using photogrammetry and image processing. The technique was validated using two concrete ties monitored with strain gauges placed inside the steel bars. The experimental results showed that one of the most important parameters affecting the accuracy of the technique is the measurement of crack widths. In comparison, the concrete strain has little effect on the final results. The technique is particularly advantageous since it is non-contact and does not impact on the bond conditions. It also does not require accessing the reinforcements. As a main conclusion, this work showed the feasibility of estimating strains inside the structure using surface measurements. This technique will benefit in the near future from further improvements namely in what concerns the camera resolution.

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