In this study, the oscillation behavior and the aseismicity of bridge piers with isolating foundations are investigated. An isolating foundation is formed by installing isolation materials such as sand, gravel and PTFE (Teflon sheet) between the footing and the pier foundation and mainly utilizes the relative displacements (sliding and rocking) between the footing and the foundation to absorb and dissipate energy during large-scale earthquakes. The governing equations of motion are derived and dynamic response analyses and model vibration tests on a single pier are carried out. The results show that this isolating system has a significant positive effect in decreasing responses during earthquakes.
Yunnan province is one of the populated areas in China where earthquakes have frequently happened especially in recent years, meanwhile a large number of highway bridges have been designed and constructed in Yunnan, whose seismic resistance design is implemented according to the (JTJ004-89). Since October 1 st 2008 the (JTG/T B02-01-2008) has been released, that has radically revised the guiding concept and performance requirement for the bridge seismic design. Then what level the bridges that have been designed and constructed before the date line are at according to the revised specification, what level according to the current that is considered more advanced in the world, and what are the differences between the Chinese specification and the Japanese one are studied. In this paper, a representative expressway bridge in Yunnan respectively according to the Chinese old, revised specifications and Japanese specification is analyzed. This calculation brings some helps to the construction of the highway bridge in Yunnan.
<p>The vibration behaviour and seismic performance of an existing girder bridge with laminated rubber bearings is being discussed. The bridge was retrofitted by ground anchors and was verified by nonlinear dynamic analysis. As a result, ground anchors had a significant effect on improving the vibration behaviour and seismic performance of the whole bridge.</p>
<p>The seismic retrofit of bridges can be classified into two ways. One is to directly strengthen the critical members of the bridges such as the pier columns, the foundations and other components. Another way is to improve the supporting condition of the superstructure or insert an energy dissipation device such as to change the existing steel bearings to the rubber ones to enhance the seismic performance of existing bridges. In this study, ground anchor was adopted to improve the seismic performance of an existing bridge abutment. According to the non-linear dynamic analysis results, this indirectly retrofit method can improve the seismic performance of an abutment effectively.</p>
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