Elevated bridge infrastructure design method

Abstract

In order to design an infrastructure of an elevated bridge, first a target ductility factor &mgr;d and target natural period T for the infrastructure are set in connection with an assumed earthquake motion. Subsequently, a yield seismic coefficient for the target ductility factor &mgr; and target natural period T is obtained from a yield seismic coefficient spectrum for the assumed earthquake motion as a design seismic coefficient K . On the other hand, a target yield rigidity K corresponding to the target natural period T is obtained. Subsequently, the design seismic coefficient K is used to obtain a design horizontal load bearing capacity H and a displacement corresponding to the design horizontal load bearing capacity H is obtained as a design yield displacement &dgr; from the target yield rigidity K . Subsequently, the design horizontal load bearing capacity H is distributed into a horizontal force H to be borne by the RC rigid frame and a horizontal force H to be borne by the damper-brace. Next, member sections of the RC rigid frame and the damper-brace are set so that the RC rigid frame and the damper-brace resist the horizontal forces H , H with ultimate load bearing capacities and displacements corresponding to the horizontal forces H , H equal the product of the design yield displacement &dgr; and target ductility factor &mgr; , that is, &dgr; &mgr; .