Seismic Performance Of Infill-Structure-Double Yield Point U-Shaped Damper Cooperative Energy Dissipative Structure

Concrete structures containing damped external wall panels(EDCP)introduce U-shaped dampers between the external wall panels and the main structure to dissipate seismic energy through their relative deformation,which can effectively control the maximum damage of the structure,but it is still difficult to avoid deformation concentration.In view of this,a double yield p oint U-shaped metal damper is proposed in this paper,and the proposed static and fatigue tests are carried out to verify the mechanical properties of the damper and reveal the influence law of the design parameters on the performance of the damper,to car ry out a systematic study on the seismic performance of the enclosure-body-double yield point U-shaped metal damper synergistic damping concrete frame structure and to reveal the control law of its seismic response,and finally to make a systematic study on the seismic performance of the seismic structure and the enclosure-body-double yield point U-shaped metal damper.Finally,the seismic toughness of the seismic resistant structure and the concrete frame structure with enclosure-body-double yield point U-shaped metal dampers is evaluated.The main work and results of the thesis are as follows:(1)The experimental study of double yield point U-shaped metal dampers was carried out.Experimental study of double yield point U-shaped metal dampers was carried out.The structural form and working mechanism of double yield point U-shaped metal dampers were introduced,two double yield point U-shaped metal dampers were designed by the theoretical formula of U-shaped dampers,and the proposed static and fatigue tes ts were carried out to investigate the influence of key geometric parameters on the mechanical properties of the dampers and the fatigue characteristics of the dampers.The hysteresis curve and skeleton curve were analyzed,and it was concluded that the ov erall hysteresis curve of the damper showed the characteristics of "double yield point and double order force",and the skeleton curve of the specimen showed a four-fold line with the performance of two yielding and energy dissipation stages.(2)The fine numerical simulation study of the double yield point U-shaped metal damper was carried out.The three-dimensional solid unit modeling method for this damper is proposed,which can simulate the load-displacement hysteresis relationship of the double-yield point U-shaped metal damper,and also analyze the local stress and strain distribution of the member,select the key geometric parameters for parametric analysis,and reveal the influence of the flat section and radius of the U-shaped metal damper on the en ergy dissipation capacity.As the radius decreases,the stiffness and yield load of the damper increase.(3)Numerical simulations of double yield point U-shaped dampers were carried out to verify the corresponding multi-scale numerical simulation methods.The seismic response,damage mode and energy dissipation capacity of the seismic-resistant structures,including EDCP concrete frame structure and enclosure-bodydouble yield point U-damper synergistic damping concrete frame structure,were compared and analyzed to investigate the specific damping mechanism and the effect of the design parameters(second-order initiation displacement/first-order yield displacement(ɑ),second energy dissipation section/first energy dissipation section stiffness,yield force(β),stiffness ratio(SR),yield force ratio(YFR))on the seismic response of the concrete frame structure.force ratio(YFR))on the seismic performance,the study shows that the maximum interstory displacement angle increases with the increase of ɑ and decreases with the increase of β.When ɑ and βreach a certain value,they will stabilize,and the excessive increase of ɑ and β will lead to the decrease of the economic efficiency of the structure.With the increase of stiffness ratio and yield rat io,the inter-story displacement angle of the structure gradually decreases while the acceleration gradually increases.When these two parameters are raised to a specific value,the change will tend to stabilize,but if they are increased excessively,it w ill lead to the decrease of the economic efficiency of the structure.Therefore,these factors need to be considered comprehensively in the actual project in order to meet the requirements of economy and practicality.(4)Based on the Seismic Toughness Eva luation Criteria for Buildings,the corresponding seismic toughness evaluation research work is carried out for seismic structures and enclosure-body-double yield point U-damper synergistic damping concrete frame structures.The specific evaluation process and criteria of the toughness evaluation are introduced.The study shows that the enclosure-bodydouble yield point U-damper synergistic damping concrete frame structure has excellent seismic toughness,and the actual repair time and cost are low,and the seismic toughness is rated as one star,and the seismic structure is rated as no star,which improves the seismic toughness level.