Seismic Behavior of Rocking Base-Isolated Bearing

• Main Authors: Chih-Hung Chao, 趙志泓
• Other Authors: Chin-Tung Cheng
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/19844713960521235132

碩士 === 國立高雄第一科技大學 === 營建工程研究所 === 101 === The objective of this research aims to improve the weakness existing in the traditional sliding base-isolated bearing such as not enough stiffness under moderate earthquakes or extensive displacement under severe earthquakes. Therefore, the motion of rocking bearing in this design will not be initiated under moderate earthquakes while rocks in rigid body motion to isolate and dissipate the seismic energy under severe earthquakes. And the superstructure remains undamaged during the excitation and self-centered due to the restoring force of self-weight of the superstructure and springs in the rocking interface after earthquakes. The vibration of the structure is damped throughout each impact of the bearing on the foundation surface. Based on the force-displacement relations and the effective damping of the systems, the seismic response of the structure may be estimated through the modified elastic response spectrum. The development of rocking bearing is investigated through shaking table tests. Seismic behavior of the isolated systems with varied parameters such as: aspect ratio of the bearing, geometry of the rocking toe (line, spherical or higher order curve), stiffness of the restoring spring and exciting wave forms were investigated. Test results show that the structure with larger aspect ratio in bearing may have longer vibrating period but still within short period, resulting in higher lateral displacement. The structure with higher order curve rocking toe has best performance in terms of least structural response. The structure with or without springs has marginal effect on the seismic performance. The structure excited by Kobe Earthquake has larger structural response than those excited by El Centro Earthquake. In addition, shear keys in the rocking interface can let the structure back to its original position after rocking. However, slips in between occurred during rocking. Therefore, theoretical damping ratio accounted for this slips and tested damping are in good agreements.