| Reinforced concrete shear wall structure is one of the most widely used structural types in high-rise building structures,in which double-limb shear walls have the advantage of double energy dissipation by coupling mechanism of coupling beam members and wall limbs,and have been widely used in recent years.As a component connecting two shear wall limbs,the coupling beam is the first seismic line of defense in shear wall structures,which can restrain the shear wall limbs under frequent earthquakes and provide lateral stiffness;under rare earthquakes,the seismic energy can be dissipated by coupling beam damage,and the main structure can be protected by the seismic design idea of "strong wall limbs and weak coupling beam".However,in practical engineering,due to the span-to-height ratio of coupling beams is generally small,they are prone to brittle shear damage,which is not only unable to fully dissipate energy,but also difficult to repair the damaged coupling beams after the earthquake,which is not conducive to improving the seismic toughness of cities.Domestic and foreign experts have proposed beams with different forms of dampers to improve the damage characteristics and post-earthquake repairability of beams,but most of the dampers in energy dissipative beams have shortcomings such as high fabrication cost,complicated processing and low initial stiffness.Therefore,it is proposed to apply friction dampers that are simple to fabricate,convenient to obtain materials,and able to provide sufficient stiffness to reinforced concrete energy dissipation coupling beams.Theoretical analysis and finite element simulations are conducted to investigate the effects of friction dampers on the seismic performance of double-limb shear wall structures.Firstly,the formulae for calculating the stiffness and load carrying capacity of friction dampers in energy dissipation link beams were derived based on the principle of equal stiffness,the design process of friction energy dissipation link beams was developed-and the damping effect of friction dampers in reinforced concrete link beams was verified,and finally the vertical arrangement of energy dissipation link beams was based on the inter-story displacement angle limits.The main research results are as follows.(1)Firstly,through the analysis of the seismic characteristics and force deformation of ordinary reinforced concrete beams,friction dampers are proposed to be applied to reinforced concrete beams as energy dissipating members.Then,based on the principle of equal stiffness,the design principle of the energy dissipation beam and the formulae for calculating the stiffness and bearing capacity of the dampers are presented.Finally,according to the working principle of friction dampers,the design method and design process of energy dissipating beams with friction dampers are developed by combining the working characteristics of truncated reinforced concrete beams.(2)The finite element model of a high-rise shear wall structure is founded by using SAP2000 finite element analysis software,and carry out the elastic-plastic time analysis under the action of rare earthquakes.The structure was strengthened with friction dampers,and the elastic time analysis under frequent earthquakes and the elasto-plastic time analysis under rare earthquakes were carried out before and after strengthening to compare the differences in the seismic response of the structure in terms of inter-story displacement,vertex displacement,base shear and energy dissipation.The comparison results indicate that the truncation of the reinforced concrete link beam and the addition of friction dampers in the span to form a frictional energy dissipation link beam have good seismic reduction effects.(3)Friction dampers are arranged at the through height of shear wall structure,which is more in number and less economical.In order to balance the seismic performance and economy of the structure,the vertical arrangement of the energy dissipation coupling beam is further optimized.Two different vertical arrangement schemes are proposed,and the effects of different vertical arrangement schemes on the seismic damping effect of friction energy dissipation coupling beam are compared.The results show that good seismic damping effect can be obtained when the friction energy dissipation coupling beam is arranged at the position where the inter-story displacement of the structure exceeds the limit. |
