Experimental study on vibration transfer from shaking table to the surrounding environment

Interaction study on shaking tables is considered necessary for such devices to guarantee their operational accuracy in vibration simulation. In such studies, accurate estimation on dynamic characteristics of foundation of shaking tables and their neighboring soil is usually required. In this regard, experimental studies on the soil or on the foundation after its completion is recommended to reduce uncertainties in operation of the table in near future. In this work a forced vibration study on the foundation of a six degrees of freedom shaking table (to be operated by International institute of earthquake engineering and seismology) have been performed. In addition to the measured excitation information collected for determination of dynamic characteristics of the foundation, that part of the vibration that transfers to the soil (in different distances form the foundation) was also evaluated. Based on the results of such measurements, dynamic characteristics of the shaking table foundation using a single degree of freedom model is estimated. Later the magnitude and the frequency contents of the vibration that was transferred to the soil in distances up to 25 meters from the edge of the foundation (in both vertical and horizontal direction) was also determined. According to the results of this study, the level of transferred acceleration to the soil reduces, rapidly, by distance from the foundation. However, the results of these measurements indicates that, acceleration magnitude in the range of high frequency vibration remains untouched.