Control of sliding-isolated bridge with absolute acceleration feedback

This paper presents an experimental and analytical study of hybrid control of bridges using sliding bearings, with recentering springs, in parallel with servohydraulic actuators. A new control algorithm with absolute acceleration feedback, based on instantaneous optimal control laws, 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 advantages in addition to those due to the passive sliding system. The experimental system used in the shake-table test is described and the results of the experiments are presented. It is shown that substantial reduction of response acceleration is possible, using hybrid control while confining the sliding displacement within an acceptable range, and eliminating almost completely postearthquake permanent offsets. Comparisons 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.