Dynamic analysis of seismically excited flexible truss tower with scissor-jack dampers

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SUMMARY In the proposed work, numerical simulations are conducted to investigate scissor-jack dampers for controlling vibrations in a seismically excited flexible truss tower. For the scissor-jack damper, new equations are developed to model the amplification factor that account for large deformations of the damper assembly. The equations are validated using computer-aided design and are used to investigate the influence of vertical deformations on scissor-jack damper amplification. Then, seismic analysis is carried out for scissor-jack dampers installed on a 3D flexible truss tower. To reduce the computational effort, a bi-model method is employed to represent the 3D truss tower as a dynamically equivalent 2D model. To describe the interaction between the structure and scissor-jack dampers, the displacement-dependent amplification factors of the scissor-jack devices and the corresponding damper forces are calculated at each time step. The response of the tower with scissor-jack damper systems is simulated for a range of damping and four major earthquakes and time histories of the displacement and absolute acceleration at each level of the tower are obtained. Results indicate that the system is effective in reducing both the displacement and absolute acceleration response of the tower without exceeding damper stroke capacity in most cases, but that damping level and earthquake intensity are important factors in the consideration of scissor-jack dampers for flexible structures subject to seismic loads. Copyright © 2011 John Wiley & Sons, Ltd.