Study On Seismic Performance Of Enlarged Viscous Damping Structure Based On Displacement Design Method

The huge energy generated by the earthquake often causes serious damage to the building structure.Installing energy dissipation devices such as dampers on the structure can enhance the seismic performance of the structure.Viscous dampers are widely used in major projects at home and abroad because of their good energy dissipation effect and convenient installation.However,the traditional viscous damper does not dissipate enough energy in the case of small displacement.The Amplified Viscous Damper(AVD)based on the leverage principle proposed by the research group can amplify the inter-story displacement and give full play to the energy dissipation of the damper.The displacement-based seismic design method can make the structure meet the target displacement.It is a seismic design method that focuses on structural performance and has certain economic benefits.This paper aims to study the seismic performance of enlarged viscous damping structure based on displacement design method.The specific research contents are as follows :(1)The concept and principle of energy dissipation technology are expounded.The research status of energy dissipation device and viscous damper and the research results of amplification damper are summarized.The displacement-based seismic design method and three commonly used methods are introduced,and the main research contents of this topic are determined.(2)The mechanical model of traditional viscous damper is introduced.The detailed structure and working principle of AVD are described in detail.Based on the principle of displacement amplification and nonlinear model,the mechanical model and energy dissipation relationship of AVD are derived.On this basis,the equivalent damping ratio expression of multi-degree-of-freedom structure with nonlinear amplification damper is derived.Finally,the target inter-story displacement angle of the frame structure is determined,and the equivalent single-degree-of-freedom system and displacement response spectrum principle based on the displacement design method are introduced.(3)The six-story concrete frame structure is preliminarily designed by PKPM,and the ETABS model is established.The equivalent single-degree-of-freedom parameters are calculated based on the inter-story displacement angle of the target under frequent earthquakes and rare earthquakes,and the floor shear force is obtained for structural design.The additional damping ratios of the damper under frequent and rare earthquakes are 8.8 % and 3.75 % respectively.Based on the principle of layered equivalence of damping ratio,the total damping coefficient of each floor is obtained and the dampers are arranged.(4)The dynamic time history analysis of uncontrolled structure and damping structure based on frequent and rare target design is carried out.The seismic performance of the damping structure is analyzed by comparing the vertex displacement,floor shear force,floor displacement,interlayer displacement angle and the hysteresis curve of the damper of the damping structure.Under the action of rare earthquakes,the relationship between the magnification of the amplification damper and the damping effect is studied.The results show that under frequent earthquakes,the average damping rate ranges of vertex displacement of VD(ordinary viscous dampers)and AVD * 2(magnified 2 times viscous dampers,and so on)structures are 29 %-32 % and 45 %-47 %,respectively.The average damping rate ranges of interlayer displacement angles are 36 %-42 % and 48 %-55 %,respectively.The average output of typical dampers in X direction is 105.18 k N and 269.13 k N,respectively.The average output of typical dampers in Y direction is 103.66 k N and254.42 k N,respectively.Under rare earthquakes,the average seismic reduction rates of the vertex displacement of VD,AVD * 2 and AVD * 3 structures are 7 %-14 %,23 %-32 % and 30 %-41 %,respectively.The average damping rate ranges of interlayer displacement angle are 19 %-21 %,34 %-37 % and 42 %-47 %respectively.The average output of typical dampers in X direction is 220.68 k N,565.05 k N and 987.29 k N respectively.The average output of typical dampers in Y direction is 211.29 k N,553.01 k N and 949.00 k N respectively.(5)Ten seismic waves are selected to analyze the vulnerability of uncontrolled structures and damping structures based on IDA method.The appropriate IM and DM indexes are selected and the four-level performance level and inter-story displacement angle limit of the structure are determined.The vulnerability results show that when the structure is subjected to the same seismic action of PGA,the exceeding probability of the damping structure reaching all levels of performance is lower than that of the uncontrolled structure.For example,the uncontrolled,VD,AVD*2 and AVD*3 structures are all subjected to the earthquake with PGA of 1.0g,and their collapse probabilities are 72.5%,36.2%,19.5%and 9.7%,respectively.Compared with the uncontrolled structure,the collapse reserve coefficient CMR of the VD,AVD*2 and AVD*3 structures increased by 41.5%,71.7%and 103.8%respectively,indicating that the amplification damper greatly improved the collapse resistance of the structure.Within a certain range,the larger the magnification,the greater the increase.