Improved seismic capacity for a smoother ride
The Nakanishi Viaduct consists of two consecutive bridges which have been designed as multispan, rigid frames.
The advantages of a multispan frame bridge are smoother ride and improved seismic behavior. In order to compensate for creep and shrinkage of the concrete in the bearings and girders, both ends of the superstructure were horizontally shifted with hydraulic jacks. Dampers were installed between the bridges to accept any possible relative movement against each other in a seismic event.
The superstructures were post-tensioned by external DYWIDAG MC 19-0.6" Strand Tendons. The piers were designed as two parallel walls each employing single bar tendons for post-tensioning.