Analyse du comportement sismique des bâtiments de faible hauteur en acier avec diaphragmes flexibles au toit

Low-rise buildings with flexible steel roof deck diaphragm are commonly found in Canada. This type of buildings is used as an industrial, commercial or recreational building. The roof is made of steel deck sheets supported by open web trusses and/or steel beams and forms a diaphragm to resist lateral loads. These diaphragms are relatively flexible and are subjected to shear deformation and bending in their plane. In Canada, the seismic design of these buildings is usually performed using the equivalent static force method. The National Building Code of Canada 2010 (NBCC 2010) provides empirical equations, based on building height, for the calculation of the fundamental period. However, when taking into account the flexibility of the roof diaphragm, the fundamental period lengthens. Furthermore, when performing a dynamic analysis, the distribution of shear stresses in the diaphragm deflects from the assumed linear variation in dimensioning. The current design method is not adapted to the reality of low-rise buildings with flexible steel roof deck diaphragm. Changes in seismic design in the NBCC and CAN/CSA-S16 (2009) substantially increased the design effort. It is therefore necessary to improve our understanding of the dynamic behaviour of low-rise buildings with flexible steel roof deck diaphragm.