日本建築学会構造系論文集
Online ISSN : 1881-8153
Print ISSN : 1340-4202
ISSN-L : 1340-4202
フェイルセーフ機構を備える鉛プラグ入り積層ゴム支承の実用化に関する実験的研究
濱口 弘樹和氣 知貴山本 雅史菊地 優
著者情報
ジャーナル フリー

2018 年 83 巻 749 号 p. 1009-1019

詳細
抄録

 The authors have been developing a new seismic isolation bearing, which consists of a lead rubber bearing (LRB) and a slider bearing as a fail-safe (FS) mechanism in series. The bearing called “FSLRB” behaves as a general LRB which is just friction connected to the building structure at either of upper or lower end, when subjected to design level earthquakes or smaller, while the sliding behavior keeps LRB away from giving excessive hardening and shear break in severe earthquakes beyond expectations. Hence, FSLRB has much higher seismic safety compared to general isolation bearings including conventional LRBs. In this paper, dynamic and quasi-static horizontal loading tests under constant or varying compressive loadings for several kinds of scaled and full-scale FSLRB specimens are conducted, to evaluate the effect of bi-directional excitations on additional torsion in the LRB part and changes in friction properties in the slider part. Ultimate performance limit of a full-scale bearing is also investigated under extremely high surface pressures beyond expectations.
 Dynamic loading tests of two types of □-200mm scaled specimens, each has different second shape factor in the LRB part, make clear that there is no apparent difference in friction properties between uni-directional and bi-directional excitations, and no damage to the LRB part due to the torsional behavior in bi-directional excitation, as far as the bearing is applied under a reasonable surface pressure around 10 N/mm2. Bi-directional dynamic loading tests of a □-900mm full-scale specimen show that there is no significant scale-effect between the full-scale FSLRB and the □-200mm scaled one on both the torsional behavior of the LRB part and friction properties of the slider part. Uni-directional dynamic loading tests of □-600mm full-scale specimens indicate that dynamic and static friction coefficients have quite low velocity dependence in reasonable sliding speed expected in the practical use. Finally, uni-directional quasi-static loading tests of □-600mm specimens show that the bearing should be applied under surface pressure of 20 N/mm2 or lower, to give a well-ordered tri-linear hysteresis curve without causing any unexpected incidents such as partial uplift of the slider part and buckling or shear break of the LRB part.
 Furthermore, surface pressure dependence of dynamic and static friction coefficients are inductively estimated applying all the data obtained in the series of the research, including the test results of □-60mm scaled slider, □-414mm scaled FSLRB and □-900mm full-scale FSLRB introduced in the authors’ preceding paper. The data indicate that both dynamic and static friction coefficients are highly affected by the dimensions of each FSLRB, those are the second shape factor of the LRB part and out-of-plane stiffness of the steel plates between the LRB part and the slider part. By introducing “effective surface pressure” reflecting the effect of the above two dimensions, friction coefficients can be even accurately estimated compared to a conventional method only using mean surface pressure.
 As a conclusion through the series of the loading tests and the considerations mentioned above, the authors think that FSLRB is ready for the practical use in a seismic isolation system with even higher safety margin compared to conventional systems.

著者関連情報
© 2018 日本建築学会
前の記事 次の記事
feedback
Top