Abstract
In this paper, the nonlinear dynamic analysis method of liquefied ground by equivalent single degree of freedom model was proposed. First, time history of the strength change of the whole ground were calculated by using the liquefaction strength curve of whole ground and cumulative damage rule. Second, by introducing this strength change into the equivalent single degree of freedom model, it is possible to easily calculate the ground response directly considering its nonlinear behaviors such as strength reduction and elongation of natural period due to liquefaction. It was verified through numerical simulations that the ground response evaluated using the proposed method generally agreed with that obtained by the effective stress analysis method. The proposed method is advantageous over other methods that only three parameters are necessary for calculation; natural period of ground, the strength of whole ground and the strength change curve of ground. These parameters can be easily evaluated from the soil boring log. The proposed method is effective as a simple evaluation method of earthquake motion in liquefied ground.
