Rapid Design On Aseismic Parameters Of Viscous Damper In RC Frame Structure

Seismic structure design mainly includes two aspects, one is the design of structure itself, and the other is the design of dampers. There are also two routes in seismic structure design with the method of equivalent viscous damping.(1)When the structure remains unchanged (mainly focusing on reinforcing of build-up structures, and partial new structures with the limit of size), the value of damping ratio needed can only be obtained by computational check repeatedly via assuming damping ratio. Then it can be equivalent as dampers.(2)When the damping ratio remains constant (focusing on most of new structures), that is, the damping ratio is set up at the beginning. The structure size can only be confirmed by computational check repeatedly via modifying the structure size. The two routes have a common defect that assuming damping ratio and modifying the structure size must be done over and over again, which brings about not only a great many of repeated calculations, but also uncertain results.Based on the route (1) and response spectrum analysis theory, this paper propose direct solving of damping ratio, which could only have been assumed in traditional seismic design. And further new seismic structure design method, named as the design method of damping ratio inverse based on response spectrum, is put forward. In terms of the route (2), it is hard to achieve the anticipated goal though modifying size of structure. However, it is relative simple to attain the approximate goal through modifying size of structure. Therefore close goal is needed, and then design seismic structure with the new method mentioned above.In order to solve the needed damping ratio, this paper take advantage of the concept of spectral reduction factor referred to FEMA273and response spectrum in China code for seismic design of buildings. The mutual relation, total damping ratio, spectral reduction factor, structural fundamental period and site condition eigenperiod, is studied and the formulas and tables, which reflecting their mutual relation, are established. This paper is not confined to the design method itself. It is proved that spectral reduction factor is linearly with storey relative rotation angle by analyzing the essence of response spectrum and mutual relation between response spectrum and storey relative rotation angle. And then it further prove scientific and rational characteristic of design method.This paper focuses on seismic parameters design for non-linear viscous dampers. The needed damping ratio can be equivalent to dampers by the concept of equivalent viscous damping.In last chapter, the rational characteristic of design method is proved again by comparing the structural response before and after design respectively applying the response spectrum method and the linear time-history method under the two engineering cases. However, big error is occur in the process of equivalence of damping ratio, therefore the theory of equivalent viscous damping remains to be improved.In addition, this paper emphatically describes and explains the concept of response spectrum. Some related concepts, regarding response spectrum, which are easily mistaken, have been also put across.