A Study Of Methods For Computing Additional Damping Ratios Of Viscous Dampers Energy Dissipation Systems

Compared with traditional seismic methods, energy dissipation methods enhance the seismic resistance for engineering structures, significantly, which have been widely employed in the field of structure vibration control. Strain energy method is generally used for estimating additional damping ratios when energy dissipation structures within viscous dampers are designed, thus it is necessary to determine magnification factors of mechanisms by which viscous dampers are arranged. The existing design formulas for magnification factors are limit applications for general structural framing systems. For viscous dampers energy dissipation system, this paper aims to establish general design formulas for calculating magnification factors of mechanisms, and to improve strain energy method using for calculating additional damping ratios.Based on analytic geometry, formulas that are used for computing magnification factors are derived, respectively when diagonal mechanism, scissors-jack mechanism, lower toggle mechanism and upper toggle mechanism are separately placed in different structures of single floor and span, including share type structures and flexural-shear type structures. And numerical examples are carried out. By using dynamics of structure and analytic geometry, equations of motion are derived respectively when diagonal mechanism, scissors-jack mechanism, lower toggle mechanism and upper toggle mechanism are separately placed in different structures of single floor and span with viscous damper energy system, including share type structures and flexural-shear type structures. And additional damping ratios of energy dissipation systems are calculated by the equations of motion verifying the accuracy of strain energy method. For structures with viscous dampers energy dissipation systems, further theoretical derivations of the amplification factors calculation formulas mentioned above are conducted to apply to general structural framing systems, and strain energy method using for calculating additional damping ratios is improved. Finally, a 12-storey steel frame structure with viscous dampers energy dissipation systems are analyzed, and the additional damping ratios are calculated by free vibration attenuation method and strain energy method improved in this paper, respectively.The results of this paper indicate that, for structures with viscous dampers energy dissipation systems, the additional damping ratios calculated by different methods are approximately equal, which verifies the accuracy of strain energy method. The magnification factors calculation methods of mechanisms established in this paper are applicable to general structural framing systems. The improved strain energy method is universally applicable and has good accuracy.