A practical method estimating both ground amplification and displacement is proposed for liquefied site during earthquake. This method consists of the 1D equivalent linear analysis, evaluation of liquefaction potential with an equivalent effective-stress concept, and estimation of shear modulus ratio for liquefied soil. The shear modulus ratios of liquefied soils are then estimated from inverse analyses using strong ground motion records at four sites in Japan. The estimated results lead finally to a simplified formula evaluating the shear modulus ratio of liquefied soil, which can be determined by the adjusted N-value derived from the standard penetration test.
