NEESR Planning/Collaborative Research: Toward Experimental Verification of Controllable Damping Strategies for Base Isolated Buildings

University Of Southern California, Los Angeles CA

Investigators

Abstract

Smart base isolation is a promising seismic mitigation technique that supplements a building's conventional base isolation layer with controllable energy dissipation devices that allow for seismic protection over a range of different earthquakes. This mitigation technique is now ready for full-scale experimental verification and validation: Japanese collaborators at the National Research Institute for Earth Science and Disaster Prevention (NIED) E-Defense shake table facility in Miki, Japan, are planning experiments in 2015 of a full-scale, base isolated building with controllable dampers in the isolation layer to mitigate damage and injury, particularly for strong impulsive and long-period excitation. The goals of this research are: (a) to leverage the results from these 2015 Japanese tests to allow for large-scale experimental verification of smart base isolation for U.S. structures, isolators and controllable dampers, and subjected to U.S. ground motions, thereby demonstrating the robust performance provided by controllable dampers in a wide array of ground motions with diverse magnitudes and spectra, as well as with damaged structures; such adaptability is impossible with conventional passive isolation devices; (b) to accelerate innovations in real-time hybrid simulation (RTHS) experimental techniques, which combine physical testing of the critical components linked with physics-based computational model simulations of the remaining structure, and that can serve to reduce future reliance on large-scale earthquake engineering experiments; and (c) to engage a community of researchers to study controlled base isolation through international collaboration, a benchmark study, and a project workshop. To achieve these goals, this research has five phases: (1) design, build and test baseline numerical and small-scale experimental models of the isolated structure to be tested on the NIED E-Defense shake table; (2) derive analytical and numerical approaches to guarantee the conditions of stability of RTHS, as well as fully develop the computational techniques that exploit the localized nature of the physical components in RTHS for highly efficient simulation of large-scale numerical models for RTHS; (3) participate in E-Defense's 2015 controllable damping base isolation experiment, working with Japanese collaborators to develop suitable control strategies and assist with the challenging aspects of their experiment; (4) use the models and tools already developed, and the experience and data from the full-scale E-Defense tests, in RTHS at the University of Connecticut to demonstrate the advances in RTHS capabilities; and (5) engage the research community by designing and releasing a benchmark study in controlled isolation based on the E-Defense and U.S.-designed structures, and by a workshop to solicit community feedback about the tools and future directions of RTHS studies. Full-scale dynamic earthquake engineering experiments, while vital for advancing seismic protection, are limited by the few facilities with the capacity to conduct the experiments and by the associated high cost of testing. These large-scale earthquake engineering experiments can be leveraged with a wider array of RTHS. RTHS must be calibrated to the full-scale results to ensure accuracy (and credibility), must be capable of accommodating, in real-time, the large-scale computational models vital to precise response computation for complex structures, and must be guaranteed stable and robust. This research will enable new technologies for seismic hazard mitigation and hybrid computational/experimental tools that complement, and broaden the applicability of, large-scale testing. Building technology will be advanced by demonstrating, in full-scale physical and mixed physical/virtual experiments, that controllable damping devices can provide significant reductions in building motion and damage during earthquakes - and doing so by capitalizing on experiments already planned by Japanese collaborators. Further, the project will enable the computational tools to support these cyber-physical experiments for realistic large-scale building models and ensure that the results are accurate. Beyond the collaboration with Japanese researchers, the development of a controllable base isolation benchmark study using models calibrated to full-scale experimental results will engage a world-wide community of researchers to multiply the reach of this project through numerous alternate control strategies. The research results will be incorporated into graduate and undergraduate classes at the University of Southern California and the University of Connecticut. An industry advisory panel will be assembled to ensure that the knowledge of practicing engineers informs the research. A workshop will ensure the transfer of the resulting tools to the hybrid simulation community so that others can take full advantage of the research results from this project. Data from this project will be archived and made available to the public through the NEES data repository. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).