M722 Basic Study on Rocking Motion Considering Sliding of Self-Standing Structure Subjected to Seismic Wave

2016 ◽  
Vol 2016.91 (0) ◽  
pp. 330
Author(s):  
Hideki SAKURAI ◽  
Tomohiro ITO ◽  
Atsuhiko SHINTANI ◽  
Chihiro NAKAGAWA
2015 ◽  
Vol 2015 (0) ◽  
pp. _G1001003--_G1001003-
Author(s):  
Hideki SAKURAI ◽  
Tomohiro ITO ◽  
Atsuhiko SHINTANI ◽  
Chihiro NAKAGAWA

Author(s):  
Atsuhiko Shintani ◽  
Tomohiro Ito ◽  
Chihiro Nakagawa

Abstract In this study, the effectiveness of coaxial circular cylinders containing a highly viscous liquid in annular spaces for reduction of rocking motion of a free-standing structure is investigated both analytically and experimentally. First, an analytical model of coupled rocking and sliding motions of a free-standing structure, including the coaxial circular cylinders, subjected to seismic input was derived. The free-standing structure was modeled as a free-standing rigid body. The cylinders were attached to the bottom of the rigid body as a damping device. We then experimentally derived the friction coefficients, inertia moments, and a damping coefficient in the rotating direction. Furthermore, using these parameters, the effectiveness of this system in suppressing the rocking motion is investigated analytically. The proposed method was determined to be very effective in suppressing the rocking motion of a rigid body subjected to a seismic input by the experiment.


Author(s):  
Atsuhiko Shintani ◽  
Takuma Yoshida ◽  
Chihiro Nakagawa ◽  
Tomohiro Ito

Abstract This paper deals with the motion of coupled cabinets containing electronics subjected to seismic input. In power plants, chemical plants, etc., several rectangular cabinets containing important electronics are always lined up in the control center. These electronics are necessary for the control of the entire plant; thus, when they are damaged, the entire plant cannot be controlled, and a serious accident may occur. These cabinets are frequently put directly on the floor. Thus, it is perceived that in the worst case, cabinets may turn over by rocking motion during earthquakes and electronics may break. Moreover, even when the cabinets do not overturn, there is a concern about a large acceleration applied to the internal electronics due to the seismic waves. Hence, the need to develop methods that can reduce rocking motion and prevent electronics damage simultaneously. First, we consider the single cabinet with electronics. The cabinet is modeled as a rotating rigid body around its corner. The internal electronics are modeled as a rigid body moving in the translational direction in the cabinet. This system is referred to as single system. We input a seismic wave to the single system and investigate the rocking angle of the cabinet and the acceleration of the electronics in the cabinet. Consequently, we consider the adjacent cabinets connected by an elasto-plastic damper containing electronics. The cabinets are modeled as rotating rigid bodies. The internal electronics are modeled as rigid bodies moving in the translational direction in the cabinets. The whole system is known as a connected system. The elasto-plastic damper has bilinear hysteretic characteristics and can absorb the energy of earthquake inputs. We input the same seismic wave to the connected system to obtain the rocking angle of cabinets and the acceleration of electronics in the connected system. In these simulations, it is assumed that cabinets do not collide with each other. Then, we investigate the effect of the parameters of the elasto-plastic damper suppressing the rocking angle of the cabinets and the acceleration of electronics. Finally, we compare the maximum rocking angle and the maximum acceleration of the single system with that of the connected system and consider an ideal method to reduce the rocking angle and the acceleration simultaneously.


2013 ◽  
Vol 2013 (0) ◽  
pp. _G101025-1-_G101025-5
Author(s):  
Yasumasa Ishikawa ◽  
Tomohiro ITO ◽  
Atsuhiko SHINTANI ◽  
Chihiro NAKAGAWA
Keyword(s):  

2013 ◽  
Vol 2013.88 (0) ◽  
pp. _8-16_
Author(s):  
Yasumasa Ishikawa ◽  
Tomohiro Ito ◽  
Atsuhiko Shintani ◽  
Chihiro Nakagawa
Keyword(s):  

2010 ◽  
Vol 2010.5 (0) ◽  
pp. 193-194
Author(s):  
Yoshihiro FUJIWARA ◽  
Tomohiro ITO ◽  
Atsuhiko SHINTANI

Author(s):  
Kazuhisa Furuta ◽  
Tomohiro Ito ◽  
Atsuhiko Shintani

Many spent fuels coming out of the nuclear power station are planned to be stored in the special site in Japan until they are reprocessed. In this site, the spent fuels are installed in a cylindrical container called canister. The canister, in tern, will be installed in the outer cylinder called cask that is a free-standing structure. When this system is subjected to strong seismic excitations, sliding or rocking motion will be induced. And, in the worst case, the cask may collide to each other or overturn. Therefore, it is very important to reduce sliding and rocking motions of the cask in order to avoid the consequent contamination of radio active substances. The authors have already reported the studies on the sliding and rocking motions of the cask subjected to a seismic excitation that contains a vibration system in it, and clarified the effects of the vibration of the inner canister. It was shown that the inner canister gives very large influences on the sliding and rocking motions of the outer cask. In this study, we applied a gyroscope at the top of the outer cask for reducing rocking motion of the cask. The effects of the gyroscope are studied for various excitation frequencies, excitation amplitudes and the structural dimensions of the gyroscope such as weight and rotational frequency. It is found that the gyroscope is very effective for reducing rocking motions of the cask-canister system subjected to seismic excitations.


2014 ◽  
Vol 2014 (0) ◽  
pp. _J1010502--_J1010502-
Author(s):  
Takatsugu KIHARA ◽  
Tomohiro ITO ◽  
Atsuhiko SHINTANI ◽  
Chihiro NAKAGAWA
Keyword(s):  

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