Base isolated/damping platforms for seismic protection of essential equipment - Energy-absorbing platforms of wire ropes

The testing series include different wire rope platforms, steel plates sandwiched by wire ropes, in different configurations supporting two different equipment-frame types, to study the three-directional seismic energy-absorbing capacity of the sets and their effects on the seismic response of tall frames holding equipment. Wire ropes traditionally are used for vibration isolation since they can provide vertical isolation. Wire ropes dissipate energy by rubbing and friction between the components of the wire ropes. Additionally, some energy dissipation foams were inserted within the wire ropes to increase damping of the overall system. The wire ropes used in the tests were donated by the VMC Group and the energy dissipation foams were donated by Roush Industries, Inc.
Earthquake testing of frames holding servers and other simulated equipment supported on different wire rope platforms were performed. 28 different sets of wire ropes were tested under different equipment configurations and different payload levels. The experimental configurations includes shear/roll and compression/roll (at 45 degree oriented) configurations of the wire ropes to study the control of rocking on tall equipment. Also, one configuration including wire ropes in shear/roll and an omni balls array was included in the series. Two frames (one slender, and one rigid) separately placed atop the wire rope platforms were included to simulate the equipment in different setups. The testing series include the frames tested as fixed base on the shake table. Each of the setup was subjected to white noise excitation, sinusoidal excitation, earthquake ground and floor motions. The floor motions intend to replicate floor accelerations recorded in multi-story buildings under historic earthquake shaking.