NEES AdaptStruct Phase 3

In the third and final phase of the NEES AdaptStruct project, the influence of negative stiffness on the performance of a seismically-isolated bridge structure will be evaluated via numerical simulations and experimental shaking table tests. The bridge is a 1:4-scale single-span structure that will be tested in various configurations that incorporate elastomeric bearings, fluid viscous dampers, and negative stiffness devices within the isolation system. In addition, the influence of bridge pier flexibility on the effectiveness of the negative stiffness device will be explored. Testing of the bridge model is being conducted by researchers from Rensselaer Polytechnic Institute, the University at Buffalo, Rice University, and Taylor Devices, Inc. The negative stiffness devices are adaptive passive devices that provide nonlinear elastic forces that act in a direction opposite to that of the restoring forces in the structure. When coupled with energy dissipation devices (positive damping devices), the combined system is expected to perform well (reduced base shear with limited increases in displacements) relative to a passive seismic isolation system having both positive stiffness and positive damping. The device was constructed by Taylor Devices, Inc., and has been subjected to cyclic tests to identify its properties. In the shake table tests, the bridge model will be subjected to earthquake ground motions having a wide range of intensities and with the model configured to represent a bridge structure with various support conditions.

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.