Report on the effects of seismic isolation methods from the 2011 Tohoku–Pacific earthquake

Nakamura, Yutaka; Hanzawa, Tetsuya; Hasebe, Masaharu; Okada, Keiichi; Kaneko, Mika; Saruta, Masaaki

doi:10.2140/siaps.2011.2.57

Cited by 8 publications

(5 citation statements)

References 3 publications

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“…The maximum acceleration on the second floor was reduced to about half compared to that on the ground. These observed data clearly shows the effects of seismic isolation (Nakamura et al 2011). Figure 12 shows the number of seismic isolated buildings in Japan from 1982 to 2015 according to the survey by the Japan Society of Seismic Isolation (JSSI).…”

Section: Effects and Applications Of Seismic Isolation Methodsmentioning

confidence: 86%

Review on seismic isolation and response control methods of buildings in Japan

Nakamura

Okada

2019

Geoenviron Disasters

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This manuscript reviews seismic isolation and response control methods of buildings, which are able to make buildings resilient against earthquakes and have become popular during the last three decades in Japan. Seismic isolation is a method of protecting a building from major earthquakes by installing isolators and energy absorbing devices under the superstructure. The manuscript describes three types of laminated rubber bearings and three kinds of damping devices. Seismic isolation provides not only structural safety, but also safety and security for people and properties in the building. Seismic isolation is also used for the retrofit of historic buildings. Response control methods utilize various kinds of dampers that are installed into a building and absorb vibration energy. The manuscript explains three foremost response control dampers: the steel hysteretic damper, the viscoelastic damper and the viscous fluid damper. The effects of seismic isolation and response control methods were verified through shaking table tests, structural health monitoring and earthquake response analyses.

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Section: Effects and Applications Of Seismic Isolation Methodsmentioning

confidence: 86%

Review on seismic isolation and response control methods of buildings in Japan

Nakamura

Okada

2019

Geoenviron Disasters

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“…The maximum acceleration responses of the Safety and Security Center when subjected to the 2011‐TPE are shown in Figure 10 25 . Although the acceleration responses were amplified at the top of the core structure, the CSI system reduced them: compared to those on the ground, the maximum accelerations on the floors in the hung structure were reduced to about half in the X direction and to about one‐third in the Y direction.…”

Section: Response Of Csi Building To 2011 Tohoku Pacific Earthquakementioning

confidence: 99%

“…In addition, SHM can show how earthquake‐proof performance is achieved by monitoring the physical status of the structure directly. The effects of SI systems have been recognized widely through the SHM of SI buildings, and the dynamic characteristics (eg, fundamental frequency, damping factor) of SI buildings have been evaluated by means of SHM 25–27 …”

Section: Introductionmentioning

confidence: 99%

Effects and dynamic characteristics of the core‐suspended isolation system assessed by long‐term structural health monitoring

Nakamura

Okada

2021

Earthq Engng Struct Dyn

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The seismic isolation mechanism of the core‐suspended isolation (CSI) system comprises a double layer of inclined rubber bearings installed on top of a reinforced core structure. A multilevel structure is then suspended from a hat truss or umbrella girder constructed on the seismic isolation mechanism. The first building to use the CSI system was the Safety and Security Center in Tokyo, Japan, whose structural health monitoring system has detected and recorded 231 earthquake motions since 2006, including the 2011 Tohoku Pacific Earthquake (2011‐TPE). The present study estimates the dynamic characteristics of this CSI‐equipped building in earthquakes, and the effects of the CSI system are revealed via the observed earthquake records. The temporal changes of the fundamental period and damping factor are estimated from the 2011‐TPE; the fundamental period increases with the deformation of the isolation level, whereas the fundamental damping factor is only related weakly to that deformation. The 231 observed earthquake records reveal that the CSI system performs seismic isolation by reducing the response acceleration of the suspended structure by roughly a half for peak ground accelerations exceeding 30 cm/s2. Daily microtremor observations are used to diagnose earthquake damage; the fundamental frequencies in each direction remain almost constant and were not changed by the 2011‐TPE.

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“…After the 1923 Great Kanto earthquake, numbers of patents in Japan were submitted. For instance, the proposal of a double column with damper was proposed [5]- [6]. In 1927, Nakamura proposed a system which consisted of several columns under a ground floor slab with around 15 meters length to the depth of the soil under the structure utilizing dampers at the joint points of the ground floor slab and these columns.…”

Section: Introductionmentioning

confidence: 99%

Effect of Base Isolator on the Structural Response of Reinforced Concrete Multistoried Building Under Seismic Loads

Tafheem¹,

Arafat²,

Chowdhury³

et al. 2017

JCEST

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This study investigates the effect of base isolator on the structural responses of multistoried reinforced concrete building under time history earthquake loading. In the present study, six-storied reinforced concrete buildings with both conventional and isolated bases have been modeled. Conventional building has been modeled with fixed support whereas base-isolated building has been modeled incorporating rubber bearing near the base of all columns. Modal analysis has been performed to get an idea of possible mode shapes of the building. After that time history analysis has been performed in order to investigate the effect of seismic loading on the building structure with respect to time. The structural responses of time history analysis such as time period of different modes, storey displacements, storey acceleration, and base shear have been obtained from both conventional and base-isolated buildings. Finally, a comparative study of structural responses has been carried out between those two structures. It has been found that fundamental time period of base-isolated building is increased by 28% compared to conventional building. Moreover, base shear value of the base-isolated structure is reduced by 69% and top storey acceleration is decreased by 75% compared to conventional building. This study reveals that isolation system reduces seismic responses significantly.

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Report on the effects of seismic isolation methods from the 2011 Tohoku–Pacific earthquake

Cited by 8 publications

References 3 publications

Review on seismic isolation and response control methods of buildings in Japan

Review on seismic isolation and response control methods of buildings in Japan

Effects and dynamic characteristics of the core‐suspended isolation system assessed by long‐term structural health monitoring

Effect of Base Isolator on the Structural Response of Reinforced Concrete Multistoried Building Under Seismic Loads

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