Analysis and evaluation of seismic mitigation effect on a steel frame building strengthened by dampers in Taiwan

Damper is a remarkable kind of vibration control device,which can be installed into a structures to provide damping force at a suitable time,and thus reduce the damage to structure caused by the earthquake action.Fluid viscous damper is sensitive to the vibration response;its damping force can change along with the vibration period and the temperature of service state,and has vibration mitigation effect when the structure is exposed to minor vibration.When earthquake happens,the dampers installed in structure will mitigate the seismic action;reduce the seismic energy introduced into the main structure system,and decrease the structural relative displacement.Working principle of fluid viscous damper is introduced in this paper,as well as the calculation method for the damping ratio of the structure system with fluid viscous dampers.Also,a method to evaluate the vibration control effect is discussed.Further more,taking an existing steel frame structure in Taiwan installed with fluid viscous dampers for example,three aspects of research are done,including(1) seismic responses of the structure under earthquake action,(2) damping ratio of the structure system under different seismic action levels,which concludes the main structural damping ratio and the damping ratio of fluid viscous dampers,(3) vibration mitigation effect after installing fluid viscous dampers.The evaluation method and vibration mitigation effect is well illustrated by this example.And the results of calculation and analysis show that retrofitting with fluid viscous dampers can produce apparent vibration control effect,and the vibration mitigation evaluation method put forward in this paper is useful and effective with certain reference value to similar engineerings.