SEISMIC RESPONSE ANALYSIS OF CABLE-STAYED BRIDGE TOWERS WITH ISOLATED BASE

摘要

The traditional approach to seismic hazard mitigation is to design structures with sufficient strength capacity and the ability to deform in a ductile manner. Alternatively, newer concepts of structural control have been growing in acceptance as design alternative for earthquake hazard mitigation. The control systems can be used as base isolators to achieve different objectives or performance goals ranging from a life safety standard to a higher standard that would provide damage control. In this study, an isolated base connection modeling is presented in order to enhance seismic behavior of bridge towers by using viscoelastic material. The material and geometrical nonlinear behavior of the base plate is considered. Nonlinear contact of the bridge towers with the base plate and concrete foundation has been demonstrated and its implementation in a finite element nonlinear analysis is presented. A time domain finite element methodology for nonlinear dynamic analysis problem is developed. That accounts for the isolated bridge towers and the inelastic behavior of base plate through an incremental-iterative procedure. A representative problem of cable-stayed bridge towers subjected to a strong ground motion is analyzed. The study shows how the proposed isolated connection enhances the seismic behavior of the bridge towers.