Abstract
Standard conditions for the tests of apparatus are as follows. Oil pressure; 35kg/cm^2, piston area; 5cm^2, weight of load; 40kg and gain constant K; 215, K'; 0.03, natural frequency of seismograph; 0.4c/sec, damping ratio of seismograph; 0.42. Seismograph used as controller is a inverted pendulum. In experiment, the frequency and the amplitude of shaking table are found as follows. Frequency c/sec 0.5 1 2 4.5 amplitude mm 100 100 50 12.5 The displacement of shaking table and isolated table were recorded by potentiometer and recording oscillograph. The results are summarized as follows. 1) These earthquake isolation apparatus by a high speed electrohydraulic servomechanism may be suitable for isolation of vibration of low frequency such as strong ground motion of earthquake. 2) These apparatus may be applied as supporting table of seismograph 3) The transmissibility of these apparatus are given as a function of frequency of ground motion and constant of apparatus. In designing this apparatus, we can pick up the constant of apparatus for the purpose of the most effective earthquake isolation of structure. 4) In the case of model test of this isolation apparatus, the minimum value of transmissibility of isolation apparatus is reduced to about 0.03, when the frequency and the amplitude of shaking table were 1c/sec and 10cm. 5) In the case of application of these apparatus to large structures, the development of special servovalve and actuator of large scale and practical construction of earthquake isolation apparatus for horizontal two direction yet remain as subject matter for further research in future.
