Research On Damping Performance Of New-type Of Bearing Structure TMD

The natural disaster, earthquake, is burst,devastating and seriously harmful to human society. Compared with the previous resistant measures such as increasing the size of element or reinforcement, the development of structural control theory is becoming the dominant trend. This paper presents a new type supporting TMD structure, This structure is the use of the existing mass of structure to control high-rise buildings. This system not only can effectively reduce the seismic response, but also can reduce component size and structure reinforcement, thus reducing the project cost, which has broad prospects for development and engineering applications.This paper studies the damping performance of a new type supporting TMD structure on high-rise buildings under seismic action. First, the paper conducted theoretical analysis of STMD、MTMD、UMTMD and got its damping mechanism,including the establishment dynamic equations of the system deriving its frequency-domain transfer function, defining displacement dynamic magnification factor DDMF. The article respectively compare damping effect of STMD, MTMD and UMTMD with each other, then study the change of displacement dynamic magnification factor by numerical analysis to obtain the affecting rule of mass ratio, damping ratio, frequency ratio and other factors. Next, models of controlled structure and uncontrolled were established in ETABS to verify theoretical analysis,(l) elastic time history analysis, mainly from the aspects of structural deformation, internal force, member forces, acceleration and modal damping energy to prove the validity of controlled structure.(2) for the same structure, through the mass ratio TMD and the main structure, damping ratio, frequency ratio, controlled modes and TMD parameters such as the number and location analysis,the article verified the influence of various factors on the damping effect of the theoretical analysis. And the article also verified when the mass ratio is constant, there is an optimal damping ratio to achieve the best damping effect of the structure.(3) Finally, through the analysis of an engineering example, to verify the damping performance of the new type supporting TMD damping structure.From the above analysis,some conclusions can be drawn as following:1)The new-type supporting MTMD structure is not only take full advantage of the internal mass of the structure, but can reduce the internal forces and deformation of the main structure in the earthquake.2)The damping effect of STMD reached the best when frequency of STMD is equal to that of external excitation load. But control frequency range of STMD is small, it is effective when its frequency is close to the frequency of the external load. frequency of external excitation load fluctuations are more sensitive to load external excitation frequency deviation once STMD frequency far, the displacement response of the structure will rapidly increase.3) The control to MTMD is the control to modes, which is different from a single TMD. MTMD works best when its frequency is close to the frequency of controlled modes, the controlled effect of MTMD for higher modes is better than lower modes. And when it controls higher modes, MTMD has wider control frequency range and lower sensitivity.4) Factors that affecting performance MTMD includes controlled modes of the main structure, numbers, location and frequency of TMD, damping ratio of primary and secondary structure, the mass ratio of secondary structure and the main structure. The conclusion of numerical analysis and finite element simulation are basically identical. With the increase of mass ratio and numbers of TMD, damping effect shows a tendency to increase then become stable. With the increase of damping ratio of secondary structure, damping effect shows a tendency to decrease after the first growth. So there is an optimal damping ratio ξopt to make optimal damping effect. To obtain the best damping effect, MTMD should be placed at the maximum absolute value of controlled mode vector.5)The energy mechanism of new-type supporting MTMD structure is that through the relative motion between main structure and sub-structure, sub-structure applies a reverse force to suppress the earthquake response of the main structure. In the meantime, the energy passed to the sub-structures was dissipated through structural damping.