Large-scale experimental evaluation and numerical simulation of a system of nonlinear energy sinks for seismic mitigation

摘要

As a novel dynamic vibration absorber, the nonlinear energy sink has been studied for mitigating structural and mechanical vibration through the last decade. This paper presents a series of large-scale experimental evaluations and numerical simulations on a system of nonlinear energy sink (NES) devices for mitigating seismic structural responses. Two distinct types of NES devices were installed in the top two floors of a large-scale model building structure. In the device system, four Type 1 NESs employing smooth essentially nonlinear restoring forces were used in conjunction with two single-sided vibro-impact (SSVI) NESs employing non-smooth impact nonlinearities. These NES devices utilize the existing structural mass and space of the model building to realize an integrated design of building structure with non-parasitic control devices. Scaled historic earthquake ground motions were implemented by a large-scale shake table as the base excitation input into the system. Direct comparisons between mitigated and unmitigated structural responses, including story displacement, column strain and base shear force, demonstrate that rapid mitigation of structural responses was achieved by the system of devices. Reductions of both peak and average values of structural responses were clearly observed. The synergistic effects obtained by simultaneously using two types of NES devices were demonstrated. To computationally investigate the mitigation performance of the devices subjected to a wide variety of ground motions, a numerical model was developed for the structure-NES system and two suites of earthquake ground motions representing distinct earthquake intensities were employed. Simulation results demonstrate that mitigation of structural responses caused by diverse earthquake ground motions can be achieved by a system of NES devices.