Magnetorheological Dampers in Civil Structures
Magnetorheological (MR) dampers are attractive new semi-active control devices that use MR-fluids to create controllable dampers. They are capable of generating large forces, offer highly reliable operation at a modest cost, and require very little power. Additionally, unlike active systems, they are not able to generate an instability in the controlled system, and can be viewed as fail-safe in that they become passive dampers should the control hardware malfunction. The results of various experimental and analytical studies indicate that these devices are quite promising for civil engineering applications.
Structural Health Monitoring
Health monitoring allows the engineer to use sensing of the structural responses in conjunction with appropriate data analysis and modeling techniques to monitor the condition of a structure. This approach has advantages which will lead to the ability to continuously observe the structural responses, as well as an improved understanding of the behavior of civil engineering structures. Furthermore, in many structures the inspection process is hindered by the fact that the columns, beams, and connections are typically covered by non-structural elements, and significant efforts are required to access these areas for visual inspection. However, the use of health monitoring techniques would simplify such procedures, allowing the engineer to ascertain the degree of structural damage without requiring visual inspection of the structural connections and components. The purpose of this research is to develop such techniques.
Fragility Curves
A relatively new concept that helps evaluating the reliability of a structure in a consequence based manner.
Practical Issues in Structural Control
In addition, the research has furthered the understanding of a number of issues that are important to successful design and implementation of structural control systems. Issues such as Control-Structure Interaction (CSI), Digital Control Implementation, and Fault Tolerant Structural Control Systems have been investigated in the research.
Benchmark Studies
Researchers at the Structural Control and Earthquake Engineering Laboratory have helped creating some of the benchmark studies that allow comparison of different techniques in fields such as structural control and health monitoring.
Vibration Control of Aero Systems
Many existing aircraft are being used well beyond their design lifetime. In addition to disturbances from maneuvering, there are many sources of vibration in aircraft due to engines, buffeting, landing, weapons firing, et. Vibration in aircraft systems may be reduced with the application of modern control hardware. The purpose of this research is to develop such systems.
Acceleration Feedback Experiments
Another focus of the research has been the implementation of acceleration feedback control strategies. These strategies have been successfully applied in active control systems with various actuator configurations, including: Active Bracing, Active Mass Driver and Active Tendon Systems. A summary of the procedures and results of the three experiments is provided in the first paper listed in this section. The subsequent papers discuss in more detail the work done in the implementation of an Active Tendon System at the National Center for Earthquake Engineering Research, Buffalo, New York and an Active Mass Driver system at the Structural Dynamics and Control / Earthquake Engineering Laboratory at Notre Dame.
Response Modification of Bridges
This project will explore economical and innovative methods for modifying the seismic response of highway and railroad bridges. The project will identify typical support and superstructure types for critical bridges in Mid-America and then develop appropriate techniques for both evaluating and upgrading existing bridges. Response modification techniques to be studied range from very simple and economical ones, for which much of the technology is already in place, to highly innovative applications of new materials, which will require some basic research.