Seismic Behavior of Reduced Scale Bridge Models with Functional Bearings

• Main Authors: Wei-I Chen, 陳威逸
• Other Authors: 張國鎮
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/56096188014667438600

碩士 === 國立臺灣大學 === 土木工程學研究所 === 95 === Study on the seismic behavior of the bridge with functional bearings is presented in this thesis. In Taiwan, only a few studies draw attention on the bearing until 1999 Chi-Chi earthquake. Before that researchers are putting much effort on the bridge column to minimize damages under large ground motion, according to the specification of seismic design of Highway bridges or seismic retrofit manual. However, with small amount of retrofitted bridges being proved available in the earthquakes and limited national budget placed on the retrofitting plan of bridges, it is important to provide an economical approach by entitling appropriate function to the bearing system. In this study, two experimental programs were carried out to understand friction/sliding mechanism for the bridge equipped with rubber bearing and PTFE-rubber bearing. Firstly, by examining the performance of same reduced-scale single span bridge from both pseudo-dynamic test and shaking table test, it is found the loading path from superstructure to substructure well satisfies the relationship of force balance at anytime, no matter the bridge is sliding or not. Meanwhile, sliding of bearing contributes a fuse-like function to protecting columns from suffering large shear force. The major difference of obtaining structure responses via those two methods is due to the velocity-related behavior of friction coefficient, giving a conservative estimation of force from the shaking table test and displacement from pseudo-dynamic test, respectively. In addition, analytical results by utilizing SAP2000N are well satisfied with the experimental data. It is useful to perform a better parametric analysis when dealing with friction coefficient and the Young’s Modulus of concrete. The behavior of a reduced-scale two spans bridge with rubber bearings in the shaking table test was introduced in the second part of the study. From experimental data and analytical results, it can be found that the sliding of bearing could reduce the demand of inertial force of the girder, as a function of isolation by which the column shear force is largely reduced in the comparison of that from using an ideal hinge- and-roller bearing simulation. Finally, the proposed analytical model is useful to predict the maximum displacement. It is convenient to check the unseating length to avoid falling in a practical manner.