In order to produce economical seismic designs, the modern building codes allow reducing seismic design forces if the seismic force resisting system (SFRS) of a building is designed to develop an identified mechanism of inelastic lateral response. The capacity design aims to ensure that the inelastic mechanism develops as intended and no undesirable failure modes occur. Since the 1984 edition, this design approach is implemented in the Canadian Standards Association (CSA) standard A23.3 for seismic design of ductile reinforced concrete (RC) shear walls with the objectives of providing sufficient flexural and shear strength to confine the mechanism to the identified plastic hinges and ensure a flexure-governed inelastic lateral response of the walls. For a single regular wall, the implemented capacity design requirements assume a lateral deformation of the wall in its fundamental lateral mode of vibration, and hence aim to constrain the inelastic mechanism at the expected base plastic hinge. This design is referred to as single plastic-hinge (SPH) design. Despite these requirements, CSA standard A23.3 did not prescribe, prior to the 2004 edition, any methods for determining capacity design envelopes for flexural and shear strength design of ductile RC shear walls over their height. Only its Commentary recommended such methods. However, various studies suggested, mainly for cantilever walls, that the application of these methods could result in multistorey wall designs experiencing the formation of unintended plastic hinges at the upper storeys and a high potential of undesirable shear failure, principally at the wall base, jeopardizing the intended ductile flexural response of the wall. These design issues result from an underestimation of dynamic amplification due to lateral modes of vibration higher than the fundamental lateral mode. The 2004 CSA standard A23.3 now prescribes capacity design methods intending in part to address these design issues. Although these methods have not been assessed yet, their formulation appears deficient in accounting for the higher mode amplification effects. In this regard, this research project proposes for CSA standard A23.3 new capacity design methods, considering these effects, for a SPH design of regular ductile RC cantilever walls used as SFRS for multistorey buildings. In order to achieve this objective, first a seismic performance assessment of a realistic ductile shear wall system designed according to the 2004 CSA standard A23.3 is carried out to assess the prescribed capacity design methods. Secondly, an extensive parametric study based on sophisticated inelastic dynamic simulations is conducted to investigate the influence of various parameters on the higher mode amplification effects, and hence on the seismic force demand, in regular ductile RC cantilever walls designed with the 2004 CSA standard A23.3. Thirdly, a review of various capacity design methods proposed in the current literature and recommended by design codes for a SPH design is performed. From the outcomes of this review and the parametric study, new capacity design methods are proposed and a discussion on the limitations of these methods and on their applicability to various wall systems is presented.

L’installation des énergies marines renouvelables s’effectue dans le respect des législations environnementales françaises. La séquence Eviter-Réduire-Compenser (ERC) est ainsi appliquée pour aboutir à une non-perte nette de biodiversité. L’objectif de la thèse est de questionner l’efficacité de cette séquence, et plus particulièrement celle de la compensation écologique, en tant qu’instrument d’internalisation et de lutte contre l’érosion de la biodiversité marine. Une approche empirique qualitative a ainsi été mise en oeuvre pour (i) identifier les facteurs écologiques et sociétaux ainsi que leurs caractéristiques théoriques qui doivent permettre à la compensation d’atteindre l’objectif de non-perte nette de biodiversité ; et (ii) contrôler si ces conditions sont vérifiées en pratique dans le cas de l’éolien en mer en Europe et en France. L’analyse met en avant les enjeux juridiques, institutionnels, méthodologiques et sociétaux à relever pour permettre à la compensation écologique d’atteindre son objectif. Sur la base de ce constat, une évaluation multicritères est proposée afin de renforcer les étapes d’évitement et de réduction pour finalement mieux définir les besoins de compensation écologique en mer. L’analyse met par ailleurs en évidence un glissement d’une compensation basée sur une équivalence écologique stricte à une compensation fondée sur une équivalence écologique relâchée. Les actions de compensation tendent à être plus généralistes et/ou davantage dirigées vers les services écosystémiques que sur les composantes des écosystèmes. Associées aux mesures d’accompagnement, elles peuvent contribuer à faciliter l’acceptabilité sociale d’un projet d’aménagement. / The installation of marine renewable energies is carried out in compliance with French environmental legislation. The mitigation hierarchy is thus applied to achieve an objective of no net loss of biodiversity. This thesis aims at questioning the effectiveness of the mitigation hierarchy and more specifically biodiversity offsetting as an internalization instrument to halt the erosion of marine biodiversity. We use a qualitative empirical approach to (i) identify the ecological and societal factors as well as their theoretical characteristics that are supposed to enable the offsets achieving the objective of no net loss of biodiversity; and (ii) control whether these conditions are verified in practice for the case of offshore wind farms in Europe and France. The analysis highlights the legal, institutional, methodological and societal issues to be addressed in order to enable biodiversity offsetting to achieve the no net loss priority. On the basis of this observation, a multi-criteria assessment is carried out to reinforce the avoidance and reduction steps of the mitigation hierarchy in order to better define offsetting needs. Ultimately, the analysis shows a shift in biodiversity offsetting based on a strict ecological equivalence to a biodiversity offsetting based on a released ecological equivalence. Offsetting actions tend to be more generalist and / or more directed to ecosystem services than to ecosystem components. Associated with accompanying measures, offsetting actions can help to increase the social acceptability of a development project.