| The traditional wind and seismic design of structures use the method of strengthening the lateral stiffness of structural members.Increasing the dimension and material strength of horizontal deflection resistance members will inevitably increase the self-weight of structures,and have the shortcomings of increasing seismic response,reducing ductility,and increasing the cost.Structural vibration control technology sets energy dissipation devices at a specific location of the structure.When external loads such as earthquakes and strong wind come,it relies on the device itself to dissipate energy firstly,which reduces the external energy transferred to the main structure,thereby improving the safety and durability of the structure.As a traditional passive control device,the viscous damper has many advantages,such as simple structure,no need external energy supply,and no destructive force on the main structure,but its constant damping coefficient and narrow output range limit its development and application.Semi-active control dampers,such as Magnetorheological dampers,can vary the fluid characteristics of dampers by adjusting the external magnetic field in real-time.It has the advantages of the extensive output range and instantaneous control force output.However,they still need external energy supply and feedback control devices.Combining the advantages of the above two control devices,based on the viscous damper,this thesis designed and developed a new type of passive variable damping energy dissipation device.The device has a simple structure and can achieve an extensive damping force output without external Energy supply and feedback control devices conditions.The thesis mainly carried out the following research:1.Based on the current theory of viscous damper,the method of change the damping orifice area to change the damping coefficients is obtained employing analysis of the damping force formula and the passive variable damping device is designed through this theory.The device can change the area of the damping orifices by mechanical means with the external excitation,thus realizing the adjustment of the damping coefficient in the process of the output of the damper.The theoretical damping force formula of the device is also deduced.2.A single-stage passive variable damping device(SPVDD)is designed and fabricated,and its performance tests under various working conditions are carried out.The results show that the device can change the damping coefficient mechanically in realtime with the change of external excitation velocity without external energy supply,and the energy dissipation effect is better than that of traditional viscous dampers.3.Based on the SPVDD,a multi-stage passive variable damping device(MPVDD)was designed and fabricated,and its performance test was also carried out.The test result shows that compared with the SPVDD,the MPVDD has a broader range of damping force output,and can simultaneously design different damping coefficient variation principle for different velocity intervals.The energy dissipation effect is better than the traditional viscous damper and the SPVDD.4.The wind-induced vibration control effects of high-rise buildings with SPVDD and MPVDD are calculated and analyzed.The results show that for SPVDD,the control effect of structural response with SPVDD increases with the increase of basic wind pressure,and it is also better than that of the traditional viscous damper.For MPVDD,the control scope of MPVDD widens with the increase of stage of MPVDD,which can realize the step control and multi-target response control of structural response under different basic wind pressure.5.Based on the performance-based design theory,the performance-based design methods of wind-induced vibration control for high-rise buildings with SPVDD and MPVDD are proposed,respectively,and a real structure illustrates the design methods.The design method can consider the multi-target control requirements of the structure under different basic wind pressures,and give the complete design process of the arrangement of dampers and damping-related parameters for different requirements.The design method can meet the comfort requirement of the structure under weak wind pressure,the durability requirement under middle wind pressure,and the safety of the structure under intense wind pressure.Engineering design examples also demonstrate the feasibility and applicability of the design method. |
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