CONTROL OF SLIDING-ISOLATED BRIDGE WITH ABSOLUTE ACCELERATION FEEDBACK

This paper presents an experimental and analytical study of hybrid con trol of bridges using sliding bearings, with recentering springs, in p arallel with servohydraulic actuators. A new control algorithm with ab solute acceleration feedback, based on instantaneous optimal control l aws, is developed. The developed control algorithm is implemented in a shake-table study of an actively controlled sliding-isolated bridge. The objective of implementing the hybrid system is to evaluate its adv antages in addition to those due to the passive sliding system. The ex perimental system used in the shake-table test is described and the re sults of the experiments are presented. It is shown that substantial r eduction of response acceleration is possible, using hybrid control, w hile confining the sliding displacement within an acceptable range, an d eliminating almost completely postearthquake permanent offsets. Comp arisons of the results of hybrid system with results of passive system are presented. The advantages of hybrid control, in addition to those due to passive control, are discussed.