Experimental Study on Vertical Component Seismic Isolation System With Coned Disk Spring

Abstract

In Japan, several kinds of three-dimensional seismic isolation system for next-generation nuclear power plant such as fast reactors have been studied in recent years. We proposed a structural concept of a vertical component isolation system, assuming a building adopting a horizontal base isolation system. In this concept, a reactor vessel and major primary components are suspended from a large common deck supported by isolation devices consisting of large coned disk springs. In order to verify the isolation performance of the vertical component isolation system, 1/8 series of shaking table tests using a scale model were conducted. The test model was composed of 4 vertical isolation devices, common deck and horizontal load suspension system. For the design earthquake, the system smoothly operated, and sufficient isolation characteristics were shown. The simulation analysis results matched well the test results, so the validity of the design technique was able to be verified. As the result, the prospect that the vertical isolation system applied to the FBR plant could technically realize was obtained.

Correlation of spectral acceleration values of vertical and horizontal ground motion pairs

“…Bradley, 2013; Lin et al, 2013) are available in the literature, little effort has been devoted to developing methods for the selection of hazard consistent vertical ground motion records. In engineering practice, however, there are many examples where the vertical component of the ground motion, in addition to the horizontal ones, plays a significant role on the structural seismic response: reinforced concrete precast structures (Bovo and Savoia, 2019), dams (Chakrabarti and Chopra, 1972; Chopra, 1966; Christopoulos et al, 2003), components in nuclear power plants (Kitamura et al, 2005), rocking systems (Vrettos, 1999), and non-structural components (Moschen et al, 2016), such as suspended ceilings and other contents sensitive to rocking, sliding, or overturning.…”

Study of isolation effectiveness of nuclear reactor building with three-dimensional seismic base isolation

“…It is widely known that LRB can be used to isolate the horizontal components of ground motion and cannot prevent vertical vibration from being transmitted EC 39,4 directly into the superstructure. In contrast to the traditional bearings of coned disk springs with only one disk spring column (Kitamura et al, 2004(Kitamura et al, , 2005Wang and Wang, 2019), CDSB is composed of one main column and several auxiliary columns of coned disk springs. Because CDSB can provide low vertical stiffness to decouple the superstructure from the vertical component of ground motion, CDSB was selected to isolate the vertical motions due to an earthquake.…”

“…Several vertical and three-dimensional (3D) isolation systems, which are the potential application to modern nuclear facilities, have been examined (Zhou et al , 2016). Devices such as rolling seal-type air springs (Suhara et al , 2002; Suhara et al , 2005), hydraulic isolation systems (Kashiwazaki et al , 2003), coil springs (Lee and Constantinou, 2018), negative stiffness devices (Cimellaro et al , 2020) and coned disk springs (Kitamura et al , 2004; Kitamura et al , 2005; Wang and Wang, 2019) were developed to provide isolation in the vertical direction. To achieve effective 3D seismic isolation, it is proposed that they be combined with laminated rubber bearings (LRBs) for horizontal isolation.…”

Influence of Vertical Equivalent Damping Ratio on Seismic Isolation Effectiveness of Nuclear Reactor Building

“…Several vertical and 3D isolation systems which have potential application in modern nuclear facilities have been examined [23]. Devices such as the rolling seal-type air spring [24,25], hydraulic isolation systems [26], and coned disk springs [27][28][29][30] have been developed to provide isolation in the vertical direction. In order to achieve the effectiveness of 3D seismic isolation, they are proposed to be combined with a horizontal isolation component.…”

“…In this way, the combination of LRB and CDSB can achieve 3D seismic isolation. In contrast to the traditional bearings of coned disk springs with only one disk spring column [27][28][29][30], CDSB is composed of one main column and several auxiliary columns of coned disk springs. The advantage of CDSB is that the constitution can be flexibly adjusted according to the requirements of the bearing capacity and vertical stiffness.…”