Elevated bridge infrastructure and design method for designing the same

摘要

In order to design an infrastructure of an elevated bridge, first a target ductility factor d and target natural period T_d for the infrastructure are set in connection with an assumed earthquake motion. Subsequently, a yield seismic coefficient for the target ductility factor _d and target natural period T_d is obtained from a yield seismic coefficient spectrum for the assumed earthquake motion as a design seismic coefficient K_h. On the other hand, a target yield rigidity K_d corresponding to the target natural period T_d is obtained. Subsequently, the design seismic coefficient K_h is used to obtain a design horizontal load bearing capacity H_d and a displacement corresponding to the design horizontal load bearing capacity H_d is obtained as a design yield displacement _d from the target yield rigidity K_d. Subsequently, the design horizontal load bearing capacity H_d is distributed into a horizontal force H_f to be born by the RC rigid frame and a horizontal force H_b to be born 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_f, H_b with ultimate load bearing capacities and displacements corresponding to the horizontal forces H_f, H_b equal the product of the design yield displacement _d and target ductility factor _d, that is, _dd.