NovoLIQ covers the following methods for calculating rd:

 

NCEER 1997

rd= 1.0 - 0.00765 Z

rd= 1.174 - 0.0267 Z

rd= 0.744 - 0.008 Z

rd= 0.50

for z ≤ 9.15 m

for 9.15 m < z ≤ 23 m

for 23 m < z ≤ 30 m

for z > 30 m

Thomas F. Blake (FugroWest Inc., Ventura, California)

Idriss 1999 and Golesorkhi 1989

Kayen et al. 1992

rd = 1 - 0.012 Z

 

 

 

 

Note: for Idriss and Boulanger 2014 method, rd from 'Idriss 1999 and Golesorkhi 1989' is used.