NEES Experimental Project for Verifying Full-Scale Semiactive Control of Nonlinear Structures

University Of Connecticut, Storrs CT

Investigators

Abstract

PI: Robert Christenson, Colorado School of Mines The objective of this proposed research is to investigate and advance the mitigation of structural damage due to natural and man-made hazards through the innovative full-scale experimental verification of semiactive control applied to structures exhibiting nonlinear behavior. The research will make use of the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) shared-use Fast Hybrid Test system at the University of Colorado at Boulder. Intellectual Merit: Newly developed semiactive technology shows promise in protecting civil structures. Semiactive control provides supplemental damping to more efficiently dissipate the energy due to dynamic loads and increases the safety and performance of the structure. Semiactive damping has typically been designed for and applied to linear structures. Civil structures, however, are typically designed to yield, thus behaving nonlinearly during extreme dynamic loading. The inherent stability of a semiactive device allows this technology to be applied to structures which, regardless of the added control, may experience damage during severe conditions. The low power requirements of semiactive devices ensure that during a major event when external power may not be available the semiactive device can continue to fully function using an alternate power source. Despite these advantages, semiactive control in the presence of nonlinear structural behavior has received limited attention and has yet to be demonstrated experimentally. The objectives of this proposal are to investigate and advance the mitigation of structural damage due to natural and man-made hazards. Innovative research is proposed to further advance the state of knowledge and acceptance of semiactive technology. This is accomplished through experimental research verifying semiactive control strategies for buildings exhibiting nonlinear behavior during large seismic events. The research will utilize the NEES shared-use Fast Hybrid Test system at the University of Colorado at Boulder to perform full-scale experimental verification. The experiment will employ hybrid testing of a semiactive 180 kN magnetorheological fluid (MR) damper while simulating in real-time the nonlinear response of a building structure subjected to suites of simulated and recorded earthquakes. Broader Impacts: Structural performance is critical to the safety and economic viability of society as observed in recent disasters. In 1999, the National Science Foundation (NSF) launched NEES to transform the nation's ability to carry out earthquake engineering research. The NEES facilities will be operational in October 2004. The proposed research can potentially have a significant impact on the advancement of semiactive control and hazard mitigation for civil structures. Successful completion of this research will lead to further studies involving physical building models and actual structures. The proposed use of the NEES shared-use site at the University of Colorado at Boulder will provide the PI with the means to efficiently and cost-effectively perform full-scale experimental verification of semiactive control for nonlinear building structures. The full-scale semiactive structural control experiment will be made available to interested researchers for a period of time at the end of the project. This will impact the ease at which additional researchers' semiactive control strategies can be experimentally verified, thus advancing the overall state of research in semiactive control for civil structures.