FREQUENCY RESPONSE CHARACTERISTICS OF THE RIGIDCOLUMN TYPE FOUNDATION

摘要

In design, a foundation assumed to be a single whole of columns called the column type foundation.To obtain fundamental data that would help establish seismic design method for the rigid column typefoundation during great earthquake, shaking table test of foundation model with different embedded depthDf and height of ground surface H were conducted. The results is the followings: 1) as H/Df increases,the foundation model respond to shaking at their respective natural frequency; 2) a model naturalfrequency smaller than that of the ground gives rise to a good degree of isolation; 3) as the inputacceleration increases, the damping constant increases and thus broadens the frequency range ofvibration; 4) the vibration of a model is affected by a phase difference as the input acceleration increases,consequently complicating the vibration mode; 5) the percent reduction of a natural frequency vs. anincreased input acceleration tends to be practically equal among the models. We also conducted a modalanalysis and verified the nonlinear characteristics of the ground by comparing the results of the modalanalysis and those of the bench test.