Passive and Semi-Active Pseudo Negative Stiffness Control of Highway Bridge Benchmark Problem

Abstract

Active and semi-active control methods for reduction of the dynamic response of structures are emerging and some are being implemented in buildings and bridges. This vast growing technology ows to recent developments of sensing and digital control techniques. Semi-active control is a promising approach for the seismic response reduction in which the control offers the adaptability of active control without requiring the associated large power sources [1-10], since the external energy is only used to modify the dynamic properties (e.g., stiffness, damping, and friction level) of semi-active device during an earthquake attack. Therefore, the semi-active control devices can be considered as controllable passive devices. The problem lies on what algorithm should control this device so that the structural response is favorable under earthquake excitation. Earthquake input energy absorption capability of structural components described by hysteretic loops plays the key role in ensuring proper seismic performance of structures. Members that have stable and large hysteretic loops are considered as ductile have been proved successful in reducing seismic responses. For very important structures, energyabsorbing devices are added to structures so that the hysteretic loops are localized only at the devices. For seismic isolation techniques, for example, hysteretic loops are also employed at the isolation devices to reduce excessive displacement. In this study, passive and semi-active control devices combined with base isolation bearings are used to generate desirable hysteretic loops. The control algorithm is designed so that the combination of the variable damper and isolation bearings yields the desirable hysteretic loops [6-11]. SEMI-ACTIVE SKYHOOK CONTROL SYSTEM