Utilisation de la surcapacite des diagonales pour l'amelioration du comportement sismique de contreventements en acier de type split-X (French and English text)

This master thesis presents a study on the inelastic seismic response of multi-storey Split-X concentrically braced steel frames. A total of 24 buildings with different plan areas and heights are examined for Victoria, BC, and Quebec City, QC. Structures designed according to current code provisions are found to develop concentration of inelastic demand over their height, which can lead to dynamic instability. This behaviour was more pronounced for the taller and larger structures located in Western Canada.; A design method is proposed to mitigate the concentration of inelastic deformations by a proper selection of the bracing members. P-delta effects also need to be included in design. Guidelines are also proposed for the accumulation of brace induced axial loads for column design. In addition, beam design load at the roof and at intermediate levels are reviewed and improved. Six structures up to 12 storeys designed according to the proposed methods are found to exhibit stable inelastic response and storey drifts within acceptable limits.