Influence of site effects and period-dependent force modification factors on the seismic response of ductile structures

A foundation factor, F, is incorporated in the National Building Code of Canada (NBCC) design base shear formula to account for amplification of bedrock ground motions as these propagate upwards through the local soil deposit (site effects). In the NBCC, the value of F is specified as a function of the local soil type and depth, irrespective of the ductility capacity for which the structure situated at the surface of the soil deposit is to be …