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原文传递 Stiffness of Rubber Bearings Considering Nonstandard Top and Bottom Boundary Conditions

题名：	Stiffness of Rubber Bearings Considering Nonstandard Top and Bottom Boundary Conditions
正文语种：	eng
作者：	Darlington, Richard E.;Becker, Tracy C.
作者单位：	Read Jones Christoffersen 1285 West Broadway Suite 300 Vancouver BC V6H 3X8 Canada\|McMaster Univ Dept Civil Engn Hamilton ON L8S 4L8 Canada;Univ Calif Berkeley Dept Civil & Environm Engn Berkeley CA 94720 USA
摘要：	Typical installations of seismic isolation assume flexurally rigid end conditions; however, in retrofit scenarios where bearings may be placed at the tops of columns or in bridges with tall piers, some rotation may occur at the boundaries. Very few experimental programs have explored the effects of these flexible boundary conditions; however, none have applied cyclic rotation at both top and bottom end plates in combination with cyclic horizontal demands, which is representative of potential loading with flexible boundary conditions. To address this gap, an experimental program on quarter-scale column-top mounted natural and lead-core rubber bearings was conducted. Rotations were applied at both the top and bottom bearing end-plates to investigate the impact of nonzero rotation boundary conditions on key design assumptions such as horizontal stiffness and rotational stiffness, and how these effects change with axial load beyond that for zero-rotation cases. Flexible boundary conditions reduce the horizontal stiffness, and the rotation-induced reduction in horizontal stiffness is dependent on the sum of the rotation at the ends, regardless of the rotation of one bearing end-plate with respect to the other. This rotation-induced decrease in stiffness is also dependent on axial load, with larger axial load leading to a higher dependency on rotation. Last, while it is known that the overlapping area method used for stability limits is conservative for rigid boundary conditions, this was shown to be true even for the bearing with a moderate shape factor (S-1 = 19.6) when supported by a flexible column. However, the overlapping area method was not conservative for the bearing tested with low shape factor (S-1 = 7.9), which exhibited a tangential stiffness of zero at an axial load less than the stability limit from this method. (C) 2021 American Society of Civil Engineers.
出版年：	2021
期刊名称：	Journal of structural engineering
卷：	147
期：	7