Effect of peak ground acceleration to velocity ratio on ductility demand of inelastic systems

Abstract A statistical analysis is performed to investigate the significance of peak ground acceleration to velocity ratio ( a / v ) on the displacement ductility demand of simple bilinear hysteretic systems. Three groups of earthquake records representative of low, normal and high< a / v ranges are used as input ground motions. The design yield strength of the inelastic systems is specified from the base shear formula in the 1980 National Building Code of Canada (NBCC 1980) and that in NBCC 1985 respectively. The former case represents the common practice of specifying seismic design base shear based on a peak site acceleration, while in the latter case the base shear is specified based on peak ground velocity and a / v ratio. Mean displacement ductility demands are obtained for the three groups of ground motions; and the corresponding dispersion characteristics are examined. The results show that the ground motion< a / v range has a significant effect on the displacement ductility demand, and it should be accounted for in design strength specification.