| Reinforced concrete frame structure has the advantages of good integrity,convenient space division,light weight,easy standardization,and material saving.It is widely used in building structures.However,in recent years,a large number of earthquake disaster investigations have found that the collapse rate of reinforced concrete frame structures during earthquakes is relatively high,and the damage is relatively serious,which has caused huge economic losses and casualties in China.The traditional design method of reinforced concrete frame structure is to achieve the purpose of earthquake resistance by increasing the strength of the structure itself and consuming seismic energy through the damage of the structure’s non-essential components under the action of earthquakes.This design method is not economical,safe and difficult to guarantee,and the seismic efficiency of the structure is low.It is a "rigor-to-rigid" structural seismic design method.Therefore,it is significant to develop a new seismic design method for reinforced concrete frame structures.Vibration reduction technology is an effective method of vibration suppression,which can effectively reduce the seismic response of structures under earthquake action.Nonlinear energy sink(Nonlinear Energy Sink,NES)is a vibration absorbing shock absorber with a wide operating frequency bandwidth.In recent years,it has been widely used in the field of vibration control.In this paper,a nonlinear energy trap is applied to a reinforced concrete frame structure,and a method for seismic design of NES frame-damped RC frames is proposed.The effectiveness of the proposed method is verified by shaking table tests and finite element simulations.The main research contents of this article are as follows:(1)Based on the analysis of the damping principle of NES shock absorber and the dynamic characteristics of the structure with NES,the dynamic equation of the damping effect of NES on the structure is deduced.The damping effect of NES on the structure is equivalent to reducing the seismic force input into the structure.Based on the research on the calculation method of seismic action reduction of structure,two seismic design methods are put forward,which are suitable for NES seismic mitigation RC frame structure.(2)Based on the main structure and the dynamic characteristics of NES,the structure and parameter design method of NES shock absorber are proposed.In order to verify the rationality and feasibility of the theoretical design method of NES shock absorber,small-scale shaking table test and mechanical property test are carried out.(3)In order to verify the accuracy of the proposed structural seismic design method in calculating the reduction degree of seismic action,a 5-story RC frame structure with and without NES is analyzed by finite element time history method,and the difference of the maximum inter story shear force before and after NES is compared.The results show that the proposed equivalent damping design method is more accurate,and the design process of this method is simple and convenient,which can be used as a general analysis method for the earthquake action calculation of NES damping RC frame structure,while the direct seismic influence coefficient adjustment method can be used as a supplementary analysis and calculation design method for special and irregular buildings.(4)Based on the application of the design method of 5-story ordinary RC frame structure designed with 8-degree fortification intensity,the NES damping design is carried out,the solid model is made,and the shaking table test of earthquake simulation is carried out to observe the failure mode and interlayer displacement index of the model in the process of earthquake,so as to verify the effectiveness of the proposed anti-seismic design method of NES damping RC frame structure.It is found that the failure mode of NES damping structure is mainly the local failure of plastic hinge at the beam end,which does not collapse after a large earthquake,which conforms to the design concept of "strong column and weak beam" and the design standard of"no collapse during a large earthquake".At the same time,the story displacement of the structure under the large earthquake also meets the requirements of the code,which proves that the structure designed by NES shock absorption meets the seismic performance standard of the original 8-degree seismic intensity,and proves that the proposed seismic design method of NES shock absorption RC frame structure is effective and feasible. |
