ABSTRACT A vibration isolation system using spring units and visco ...

2. VIBRATION ISOLATION SYSTEM
2.1 Details of the system
Helical steel springs are used to support the weight of the building providing a low vertical natural
frequency of the spring supported building, so that the higher frequency parts of the traffic
vibrations can be isolated to a high degree. The visco-elastic dampers react in all three
dimensions. They can, therefore, be placed near to the corners of the building.
Both, springs and dampers, are concentrated in several locations where the number of spring units
and dampers is controlled by the load distribution of the upper structure.
The system has the following characteristics:
1) With helical spring support of the building its natural frequencies, both in vertical and horizontal
direction, can be set quite low, so that vibration and structure borne noise from subways or
other traffic is highly reduced.
2) Since visco-elastic dampers react three dimensionally, it is needless to arrange dampers for
vertical and horizontal direction independently, and it is, therefore, easy to concentrate the
devices in the corners.
Fig. 1 Sectional plan of the building Fig. 2 Arrangement of devices in the building