Design of a Super Multispan Continuous Girder Bridge Using Enhanced Seismic Response Modification Technologies

Abstract

This paper reports the state-of-theart seismic design concept utilizing an extensive combined application of seismic response modification devices, including elastomeric bearings, seismic dampers, and low-friction slide bearings with a particular layout for the super multispan continuous girder bridges, used in the Imagiregawa Bridge project in Japan. The baseline of the design concept is the reduction of the resilient force introduced by the bearing system, while a high level of structural damping is introduced with the use of high-capacity seismic dampers to utilize the seismic force reduction effect of the seismic isolation concept. There are other great advantages in the present design concept for long super multispan continuous girder bridges: statically indeterminate forces that act on multispan continuous girders supported by elastomeric bearings induced by temperature changes, desiccation shrinkage, and creep can be reduced so that any unfavorable effects to the seismic response are reduced. It also eliminates the necessity for adjustment of elastomeric bearing installation with the “post slide” procedure during construction. Since the elastomeric bearings and seismic dampers are installed on a limited number of piers, 22% reduction of the projected construction cost of the substructures is achieved as compared with conventional seismic isolation design.