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This paper presents analytical and experimental results on ductility of reinforced lightweight concrete beams and columns in the form of moment curvature relationships, and compares the response with that of normal reinforced concrete members. The experimental part is limited to flexural tests on beams made of lightweight concrete. The latter is obtained with natural lightweight aggregates. Concrete and steel stress-strain models in compression and tension are integrated analytically through the section in order to derive the resulting moment and axial force. Lightweight concrete beams and columns showed a more ductile behavior than normal concrete members and the analytical model reproduced the response with very good accuracy. The lightweight ductility was more pronounced in columns subjected to axial compression forces and bending.

If steel manufactures usually comply with the minimum code specifications, the nominal yield strength of rebar can however be significantly exceeded in many countries, depending on the steel manufacturing processes. Such an increase in yield strength can have negative effects on the flexural behavior of beams designed as tension controlled, and reduce their ductility, an essential property in seismic resisting structures. An experimental and analytical study of the flexural behavior of reinforced concrete (RC) beams was conducted through the investigation of the Moment-Curvature relationships and the ultimate steel strains. The main variable was the level of the actual steel yield stress as compared to the nominal value. It was found that unexpectedly high values of steel yield stress reduce the beam ductility and violate the tension-control condition which was enforced in the design stage. Appropriate design corrections are proposed to account for high yield stress values in order to achieve the desired ductility of beams while maintaining the moment capacities.

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Tests are reported to investigate the shear bond strength of epoxy resin adhesives to concrete and steel adherents. Two types of tests were carried out on composite steel-epoxy-concrete specimens -pull out tests, in which failure always occurred through the concreteglue bond, and single and double lap tests to examine the epoxy shear adhesion to steel adherents. It was found that the distribution of the longitudinal forces and shear stresses along the joint was exponential for both types of tests. The shear bond strength of epoxy to concrete varied almost linearly with concrete strength. However, variations in the adhesive layer thickness, in the range 0.5 to 3.0 rom, had practically no effect on the strength of the pullout or double lap specimens. The results obtained show that both the pull out and double lap shear tests can be carried out with a good degree of accuracy and consistency.

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En vue de constituer une base de données expérimentales précise et liable pour la validation et la qualification des outils de simulation des mouvements induits par les opérations ´un tunnelier, deux plots ´essais de ĺextension de la ligne D du métro de Lyon ont été intrumentés intensivement. Dans cet article, on présente les résultats de mesures ´une auscultation de deux sections transversales de cette ligne. En faisant une comparaison avec les mesures ´autres pro-jets antérieurs, on a mis en évidence que ĺinstabilité du front de taille et le vide annulaire dégagé après ĺéchappement de la jupe constituent les sources principales de tassement à court terme. A partir de ces mesures, on propose, ensuite, une nouvelle procédure de simulation numérique en déformation plane qui dent compte des différentes étapes de construction. La comparaison des mouvements observés et simulés montre que le comportement des terrains meubles est mieux modélisé par un contrôle en déplacements que par un contrôle en contraintes à la périphérie de ĺexcavation. In order to obtain a precise and reliable measurement database for the validation and qualification of simulation tools describing the deformations induced by tunnelling operations, two sites on the Lyon Metro D line extension have been intensively monitored. This paper presents the results of measurements from two experimental transverse tunnel sections of this line. A comparison with data from previous projects shows that the instability of the tunnel face and the annular void created by the passage of the shield constitute the principal sources of short-term settlement. Based on these measurements, a new procedure of numerical simulation in the plane strain conditions is proposed, taking into account various stages of construction. The comparison of the observed and simulated movements shows that the behaviour of soft ground is better simulated by displacement control than by stress control of the periphery of the excavation.