Mid-height isolated tall, slender vessel

A set of earthquake-simulator experiments were conducted to investigate the utility of mid-height seismic isolation of tall, slender equipment. The test specimen was a 240-inch-tall vessel with an outer diameter of 60 inches and a wall thickness of 1 inch. The vessel was supported on a stiff steel frame at its mid-height, near its center of gravity. Two sample internals were attached to the vessel head. The vessel was tested in three configurations: 1) non-isolated, 2) isolated using single Friction Pendulum (SFP) bearings, and 3) isolated using Triple Friction Pendulum (TFP) bearings. The vessel was subjected to three component ground motions, selected from the PEER NGA-West 2 database, using a 6 degrees-of-freedom earthquake simulator at the University at Buffalo. Test results demonstrated that mid-height seismic isolation generally enables a very significant reduction in horizontal spectral accelerations in the vessel and its internals with respect to those in the non-isolated configuration. The experiment data will help engineers to validate numerical models for analysis and design of isolated safety-class equipment in nuclear power plants.