ACTIVE CONTROLS IN BRIDGE ENGINEERING

ACTIVE CONTROLS IN BRIDGE ENGINEERING

ABSTRACT

Bridges are the key elements in any road network. The Conventional design procedures for bridges are generally based on two requirements namely safety and serviceability. For the Safety concerns the bridges are designed by Strength approach, which ascertains that the strength of various elements is greater than the demand at extreme loading condition. In the presence of seismic loads, the bridges designed with strength approach can sometimes be untenable both economically and technologically. To overcome this problem isolators are provided to isolate the seismic ground motions or passive energy dissipation devices are used to dissipate the vibration energy and reduce the dynamic response. Recent trends are to use newly developed active control devices which have unique advantages and provide more control authority and adaptivity when compared to alternative ways. Based on the changes of structural responses and external excitations, these intelligent systems can actively adapt their properties and controlling forces to maximize the effectiveness of isolation system, increase the life span of bridge and allow it to withstand the extreme loading effects. A purely active control system may not have proven reliability. In nutshell, an active control system incorporating devices like active tendon, bracing and mass dampers has an advantage of being a SMART system but suffers in terms of external energy utilization, destabilization and complication of system
performance.

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