NEESAdaptStruct

NEESR-SG: Development of Next Generation Adaptive Seismic Protection Systems

Completion of first phase experiments for proof of concept

Reseach Team

  • A. A. S. Sarlis (UB), D. T. R. Pasala (Rice U.) – PhD Candidates
  • M. C. Constantinou (UB), A. M. Reinhorn (UB), D. Taylor (Taylor Devices, Inc), S. Nagarajaiah (Rice U), - PI’s

By designing a ductile structure and letting the structure yield under strong earthquakes, the forces acting on the structure can be reduced to the level dictated by the yield level. However, the structure undergoes permanent displacement. In this study, yielding is emulated in a structural system by adding an "adaptive negative stiffness device" and shifting the “yielding” away from the main structural system—leading to the new idea of "apparent softening and weakening" that occurs ensuring structural stability at all displacement amplitudes. For this purpose a novel adaptive negative stiffness device, NSD, that is capable of changing the stiffness as a function of device displacement, is developed.

In the first phase of this study, the prototype of a negative stiffness device was designed at University at Buffalo (UB), built by Taylor Devices, Inc., and tested by the researchers at UB and Rice Univeristy in a three stories structural model isolated with elastomeric bearings. Without the negative stiffness device the accelerations in the structure are larger than desired. In the presence of the negative stiffness devices, the model experiences lower accelerations and base shear, while the increased deformations are controlled and reduced by viscous-fluid supplemental dampers. First phase testing verified the concept and determined the influence and efficiency of “gaps” in the device, the imperfectives in construction and placement of devices, and in the full characterization of the rigid body dynamics influencing the devices.

Sponsor

This project is supported by the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Program of the National Science Foundation under Award Number CMMI-0830391.

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