| The structural engineering community has been making great strides in recent years to develop performance-based earthquake engineering methodologies for both new and existing construction. For structural control to gain viability in the earthquake engineering community, understanding the role of controllers within the context of performance-based engineering is of primary importance. Design of a structure/controller system should involve a thorough understanding of a controller's ability to enhance structural performance, such that the most effective type of controller is selected.; This study focuses on steel moment resisting frames and three types of possible controllers: (1) friction pendulum base isolation system, FPS (passive); (2) linear viscous brace dampers, VS (passive); (3) and active tendon braces, ATB. Two structures are selected from the SAC Phase II project, the three story system and the nine story system. Simulations of these systems, both controlled and uncontrolled, are prepared using the three suites of earthquake records representing three different return periods. The system performance is judged based on both roof and interstory drift, normalized dissipated hysteretic energy, and peak floor acceleration demands. This investigation has the following specific objectives: (1) To evaluate the effect of the various controller architectures on seismic demands as described through performance-based design criteria; (2) To evaluate the sensitivity of the structure/controller performance based on a variation of control parameters, load levels and structural modeling; (3) To evaluate different systems using a probabilistic format.; Results indicate that structural control systems are effective solutions that can improve structural performance. All three control strategies investigated can significantly reduce the seismic demands on a structure, thereby reducing the expected damage to the structure. However, no one system is consistently the best at all hazard levels. The use of a probabilistic format allows for a consideration of structural response over a range of seismic hazards. Stable relationships can be developed between the spectral acceleration and controlled structural demands. Similar relationships are also possible for the demands on the control system, such as the peak bearing displacement for the isolation system. As a result, fewer control analyses may be required to estimate the expected structural behavior. |
