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Experimental Testing of the Resilient-Friction Base Isolation System.
Clark, P. W.; Kelly, J. M.
National Science Foundation, Washington, DC., July 1990, 162 p.
Identifying Number(s)
The report describes a series of earthquake simulator tests of a five-story steel frame founded on Resilient-Friction Base Isolation (R-FBI) bearings. These bearings use alternating plates of teflon and stainless steel encircling a hard rubber core to absorb damaging horizontal ground motions. System identification tests were performed on the test structure to characterize its fixed base and isolated response, then the frame was subjected to a variety of earthquake motions. To a varying degree for each signal, the isolation system limited the accelerations transmitted to the frame and reduced the amplification of accelerations toward the top of the frame that is typical in conventional fixed-base structures. Measured interstory drifts were below levels likely to cause serious damage to structural or nonstructural components. The sliding displacements in the bearings were smaller than predicted by previous analyses because the measured coefficient of friction during the shake table tests was larger than that predicted by the material properties. The frequency response of the test frame depended greatly on the characteristics of the input signal. In general, the bearings tended to spread the input energy over several modes and a wide range of frequencies for each mode. Attempts were made to develop an equivalent linearized model for the isolated structural system.
Dynamic response; Bearings; Vibration isolators; Earthquake resistant structures; Dynamic tests; Earthquake engineering; Steel structures; Structural vibration; Earthquakes; Test facilities; Vibration damping; Shear properties; Structural members; Displacement; Resilient-Friction Base Isolator; Structural analysis; Seismic waves