It is preferable to determine the site designation as XV on the basis of the average shear wave velocity,, calculated from in situ measurements of shear wave velocity. This site designation will typically result in a lower seismic demand than a site designation XS determined using the energy-corrected average standard penetration resistance,, or the average undrained shear strength, su.
Further information on site designation can be found in the Commentary entitled “Design for Seismic Effects” in the “Structural Commentaries (User’s Guide – NBC 2020: Part 4 of Division B)”.