Study On Energy Dissipation And Seismic Mitigation Performance Of HADAS Damper

As a new type of displacement-dependent ADAS (Added Damping And Stiffness) dampers, HADAS damper consists of several mild steel energy-dissipation plates, which can dissipate a large amount of seimic energy induced into the structure by their out-of-plane inelastic hysteresis cycles and effectively improve the seimic behavior of structure. Before yielding, the damper adds up the stiffness of structure, and increases the damping of structure after its yielding. Therefore, HADAS damper is suitable for new-construct building and retrofit of existing structure. Focused on the energy dissipation and seismic response reduction of HADAS damper, the research work of this thesis can be summarized as follows:1. As the main research work of this thesis, a shake table test is designed and conducted on a three-story, steel moment-resistant frame structure (referred to as MRF) both with installaion of twelve HADAS dampers (referred to as HADAS-frame) and its bare configuration (no any HADAS dampers). The seismic reponses of MRF and HADAS-frame under different ground motion inputs of a range of intensity levels through different directions such as story drift, acceleration, base shear and so on are achieved. The performance analysis and results comparison between MRF and HADAS-frame indicate that the structural deformation and column shear force are significantly reduced, and the energy dissipation capacity of the structure is increased so that the damage and injury of major structure can be decreased or even avoided. The hysteresis energy dissipation capacity of HADAS damper and its influence on structural seismic behavior are evaluated by the hysteresis loops of dampers and their mechanical characteristics obtained from the test.2. Through theoretical analysis and finite element analysis methods, the relationship between the steel property, size parameters and the mechanical characteristics of HADAS damper, such as initial stiffness, yielding displacement (or yielding force), latral stiffness and torsional stiffness, are also analyzed in this thesis. Then a cyclic loading test of a HADAS damper used in the shake table test is performed to obtain the basic mechanical parameters of the damper and to make comparison with the results of shake table test and design value. The test results show that the hysteresis loop of HADAS damper is stable and with large areas, and its ultimate displacement reaches 35mm, which can completely meet the structural requirements of deformation.3. Considering geometric nonlinearity, material nonlinearity and link object material nonlinearity, a nonlinear dynamic analysis is performed to both MRF and HADAS-frame model by adopting general structural analysis program SAP2000. And the seismic energy dissipation capacity of HADAS damper, when major structure enters into inelastic phase, is evaluated.On the basis of above, some suggestions to practical engineering application of HADAS damper are pointed out and the problems requiring further studies are discussed.