Source google image: https://i1.rgstatic.net/publication/255785503_Seismic_Isolation_Using_Slide_and_Rubber_Bearings_Large_Amplitude_Free_Vibration_Tests_on_Rapolla_Residence_Building/links/0deec5214975e34a4d000000/largepreview.png
R 1.20 isolation
Source google image: https://i1.rgstatic.net/publication/255785503_Seismic_Isolation_Using_Slide_and_Rubber_Bearings_Large_Amplitude_Free_Vibration_Tests_on_Rapolla_Residence_Building/links/0deec5214975e34a4d000000/largepreview.png