Study On Real-time Force Tracking Scheme And Negative Stiffness Control Of MR Dampers

High-rise building can effectively reduce the displacement response of the structure under earthquake by structure vibration control,but the top acceleration is hard to get effective control,meanwhile negative stiffness control can reduce the acceleration response of the structure effectively.The MR damper can realize the negative stiffness control of the structure intelligently without additional use of other mechanical devices and its negative stiffness control force can be achieved through changing the drive voltage.However,the uncertainties of MR damper model and the difficulties in real-time damping force tracking have caused great difficulties to the negative stiffness control of the structure.Therefore,this paper proposes the hyperbolic tangent function model of MR damper and study piecewise linear interpolation real-time control force tracking scheme based on model,the negative stiffness of MR damper is studied by the Open Sees finite element software.The research is shown in details as follows:(1)The force-electric mode of MR damper under constant voltage is proposed based on hyperbolic tangent function,the modeling method of nonlinearity because of shear yield at the low velocity zone and difference of damping force at high speed zone when the piston rod of the damper accelerates and decelerates are studied.The validity and simulation error of hyperbolic tangent model are studied by performance test and variable frequency amplitude test of MR damper.(2)A second-order dynamic system model of the current source and a first-order filter model which can describe the relationship of current and magnetic of MR damper are build to describe the relationship between electric field and magnetic field of MR damper,Meanwhile,it extends the application range from constant voltage to variable voltage.Finally,the viscous damping force and the negative stiffness damping force are realized by MR damper through simulation and test.(3)A secondary development code of MR damper material subroutine and the subroutine of real-time damping force tracking algorithm by Open Sees finite element software is developed to further study the negative stiffness control of high-rise buildings with MR control under earthquake.