Abstract
In order to consider nonlinear characteristics of soft ground, we propose a new amplification function which has four parameters such as an amplification factor during weak motions and the upper limit depending on shear strength of the soil deposits. Earthquake response analyses are carried out with many conditions and 4 parameters are decided. Topography classifications and a predominant period have been often used as ground parameter, but in late years the use of average S-wave velocity increases. Therefore, we connect average S-wave velocity to 20m or 30m deep with four parameters in order to apply to the area where boring data are provided to high density.
