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皆川 佳祐*; 藤田 聡*; 山口 彰*; 高田 孝*; 栗坂 健一
日本機械学会論文集,C, 79(804), p.2684 - 2693, 2013/08
Seismic isolation is one of effective and widespread technology that can reduce response acceleration of superstructure. The most popular isolation device is laminated rubber bearing. In general it has linear stiffness against seismic load in the design deformation range. However it has nonlinear stiffness in case of large deformation. That is a hardening property in horizontal direction and a softening property in vertical direction. In the meantime, application of probabilistic safety assessment to seismic evaluation is attracting attention in order to improve seismic resistant reliability. In seismic PSA, accurate numerical simulation is required for not only normal earthquakes but also huge earthquakes that have low occurrence frequency. Therefore to express above-mentioned nonlinearity of rubber bearings is required. Thus this paper describes nonlinear simulation of a seismic isolated structure. Both the hardening characteristics of horizontal direction and the softening characteristics of vertical direction are expressed by multilinear models. Additionally the analysis model of horizontal direction considers a habituation effect of rubber. Response of nonlinear simulation is compared with linear simulation. As a result, it was confirmed that nonlinearity of rubber bearings debases the isolation performance.
藤田 聡*; 皆川 佳祐*; 山口 彰*; 高田 孝*; 栗坂 健一
Proceedings of 15th World Conference on Earthquake Engineering (WCEE-15) (USB Flash Drive), 9 Pages, 2012/09
In Japan, applications of seismic isolation systems using rubber bearings to new generation Nuclear Power Plants (NPPs) and Fast Breeder Reactors (FBRs) have been considered in order to enhance seismic safety. However, the isolation performance will decline in case of huge earthquakes, because of nonlinearity of both horizontal and vertical restoring characteristics of rubber bearings. In addition, Probabilistic Safety Assessment (PSA) has been introduced to seismic design. However the application of PSA to seismic isolation has not been attempted yet, and accurate seismic response simulation of isolation system required for the application. Authors carried out seismic response analysis that considers both horizontal and vertical nonlinearity of rubber bearing. Influence of nonlinearity of rubber bearing upon response of building was investigated by the analysis.
西野 裕之; 藤田 聡*; 皆川 佳祐*; 高田 孝*; 山口 彰*; 栗坂 健一
no journal, ,
上下動に起因する鉛直荷重の変化により生じる剛性ハードニング開始点の変動が応答に与える影響を把握するため、水平動と上下動を連成させ、建屋と機器を独立としたモデルを構築し、入力地震動の大きさを複数設定した地震応答解析を実施し、連成効果を評価した。
