Vibration Reduction Performance And Robustness Of A New Pounding Tuned Rotary Mass Damper

In this paper,the pounding tuned rotary mass damper(PTRMD)based on hollow floor is proposed to improve the performance of TMD.PTRMD has the advantages of insensitivity to parameters,stable control effect and high efficiency.PTRMD is composed of a ball,an arc track,stops and viscoelastic material,etc.PTRMD is placed inner of hollow-box to take full use of the spare room in the hollow floor,and no extra architecture space is needed.The ball inside the arch path is excited by the vibration of the main structure generated by wind or earthquake.Therefore,a part of energy input to the structure could be absorbed through the rolling of the ball,then dissipated through the collisions between the ball and viscoelastic materials.PTRMD is a combination of tuned rotary mass damper(TRMD)and impact damper,as it plays the part of TRMD when the external excitation is small,and acts as the impact damper when the excitation is really large.It has a great advantage over traditional TRMD due to the introduction of collision mechanisms.The piecewise equations of motion for the single degree of freedom(SDOF)and multiple degree of freedom(MDOF)system installed with PTRMD are developed based on Lagrange’s equation.The equations of motion are divided into two periods,namely the free-rolling period of the ball and the colliding period between the ball and the visco-elastic materials.The fourth-order Runge-Kutta method is used to numerically simulate the time history of the system.The optimal collision angle of PTRMD under different excitations is obtained from numerical simulation results.Control performance of structure with PTRMD and TRMD is compared both in free vibration and forced vibration cases.The frequency spectrum of the damper is plotted by changing the frequency of the forced vibration excitation so the control bandwidth is obtained.The effect of dampers on each layer is compared by placing PTRMD at different levels.It is found that PTRMD placed on the top layer is more effective in controlling the fundamental frequency response of the structure,and the damping effect of all layers is basically the same when PTRMD is fixed in a certain layer.Based on the top layer layout of PTRMD,its damping performance under various earthquakes with different strengths was studied.It is found that PTRMD can’t reduce the peak response effectively but can largely control the root mean square(RMS)response of the structure.Under the influence of earthquakes of various strengths,PTRMD has the best shock absorption effect under a 7-degree earthquake.PTRMD can still dissipate energy under high-intensity earthquake,while TRMD has no effect unless small earthquake.Therefore,there are obvious advantages of using PTRMD devices under the action of medium-high-strength earthquakes.In addition,the dynamical parameters of the structure tend to perturb under the action of earthquakes in the multi-degree-of-freedom structure.There are a lot of reasons that will cause the frequency of the damper to be inconsistent with the natural frequency of the structure.Such as,the degeneracy of the stiffness of the structure,the change of function,and the error of the PTRMD’s track production.It is necessary to study if the vibration reduction performance of the controlled structure and the damper continue to be effective.This paper compares the robustness of TRMD and PTRMD under free vibration and forced vibration.It is found that PTRMD is greatly influenced by low detuning frequency,and when the frequency is high detuned,the damping effect is reduced very little.All in all,it can be conclude that compared with TRMD,PTRMD not only has better damping performance,but also has stronger robustness.