Probability Distribution Characteristics and Statistical Parameters of the Horizontal Stiffness of Rubber Isolation Bearings

ABSTRACT

The manufacturing of rubber bearing is complicated, the horizontal stiffness of the final product maybe greatly affected by the uncertainties during the processing, thus, it is necessary to study the distribution characteristics of the rubber bearings’ horizontal stiffness, and its influence on the seismic performance of the isolation structure. The rubber layer thickness was taken as a comprehensive index, measurements were carried out before and after vulcanization, the relationship between the rubber layer thickness and the variation of bearing’s horizontal stiffness was deduced, and an optimization method to reduce the variation of bearing stiffness was proposed. Then, based on the equivalent shear stiffness samples of 224 rubber bearings of 3 different specifications produced by two manufacturers, systematic statistical analysis and probability distribution tests were carried out. Result shown that the equivalent shear stiffness obeys the I-type minimum-value distribution. Finally, the influence of the variation of the bearing’s stiffness on the seismic performance of the rubber bearing isolation structure was studied. The results shown that the probability distribution form of the rubber bearings stiffness has a certain influence on the adjustment coefficient $\psi$ of the isolation structure, but the damping effect of the isolation structure still has sufficient safety reserve according to China’s Code for Seismic Design of Buildings.

KEYWORDS:

• Rubber isolation bearing
• rubber layer
• horizontal stiffness
• probability distribution
• statistical analysis

Acknowledgments

Financial support from the National Key R&D Program of China [NO. 2017YFC0703600] is gratefully acknowledged. Support was also provided by the Scientific Research Foundation of Graduate School of Southeast University [NO. YBPY1922].