Development of Seismic Control Devices unifying some bridge systems

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This work deals with influence of bi-directional cyclic displacement loading on the ductility of hollow circular steel columns and to develop a seismic verification method for bridge piers, with pipe sections, when subjected to coupling action of two horizontal earthquake components. For this purpose, nonlinear numerical analyses are performed on Finite Element models by setting radius-thickness ratio and slenderness ratio as main design parameters. The strain-based ductility formulas are developed separately for uniand bi-directional cyclic loadings, and based on these formulas a seismic verification method is proposed. To confirm this method, nonlinear dynamic analyses are carried out on three different beam element models of bridge piers. The deformation and strain performances are evaluated by displacement-based and strain-based methods. The comparative study shows that the strain-based seismic verification method is critical than displacement-based method. Further, comparison between allowable values given by past ultimate strain formula indicates that the formulas developed in the present study are more adequate to use in seismic verification of circular steel bridge piers when subjected to two directional earthquake motions at the same time.Finally, some various problems installing seismic control device into bridge systems are discussed. As a result, it was found that the method placing seismic control devices optimally is not developed yet. Therefore, newer procedure locating seismic control devices into bridge systems will be developed with reconsidering some structural parameters.