抄録
Described in this paper are an observation and analytical verification on seismic responses of a long-span cantilever truss bridge with 980m-long. Some earthquake records have been obtained from this bridge and dynamic analyses were carried out in order to verify the natural frequencies and damping properties. It was found that natural frequencies of analyses using the three-dimensional model are good agreement with those of observations. However it can be noted the damping ratio which is normally applied in analyses may give small displacement response for the relatively long period mode. Therefore we recommend that 1% of damping ratio should be applied for such the mode. Moreover it was confirmed that the friction between I-bar and a pin at hinge portions of cantilever bridge affect the bridge response in the longitudinal direction.
