COMPARISON OF SEISMIC RESPONSE BETWEEN BRIDGE WITH SLIDING-TYPE BASE-ISOLATION SYSTEM AND THAT WITH LAMINATED RUBBER BEARING

Comparison of dynamic characteristics between bridge with sliding-type base-isolation system and that with laminated rubber bearing under earthquake motion has been made. 4-span continuous steel box girder elevated bridge with lead laminated rubber bearings which is located on Bay-area Line of Hanshin Express Highway is selected as the subject of study because its dynamic responses under Kobe Earthquake were measured actually. Four kinds of laminated rubber bearings whose physical properties are different are taken into account in this study. Several types of earthquake motions such as Kobe Earthquake, Pacoima Earthquake, Taft Earthquake, and so on whose amplitude is appropriately changed are used as input earthquake motions. The result shows that from the point of view of reduction of girder acceleration, sliding-type base-isolation system is more effective than laminated rubber bearing in case that stronger earthquake attacks the bridge although the relative displacement between superstructure and substructure is considerably large. It has also been revealed that any significant difference is not recognized between these two types of base-isolation systems in case that the relatively weak earthquake occurs.