Theory And Experiment Study On Seismic Behavior Of High Damping Concrete Shear Wall With Concealed Bracings

The high damping concrete is a kind of concrete with iMPact toughness and high damping performance.It is generally adopted in concrete by adding a certain proportion of polymer,and it is a development direction of concrete technology.With the rapid development of high-speed railway in our country,how to decrease the vibration of surrounding buildings when high-speed trains went by has become a very important and challenging issue.Damping installations are mostly appended to mitigate vibration by increasing the performance of damping of structures,however,it always makes structural design and construction more inconvenient.If the high damping concrete in such structures is widely used,the purpose of reducing vibration can easily be achieved.Reinforced concrete shear wall is a kind of lateral resisting structure system that is widely used in buildings.But because the deformation capacity of shear wall is poor,the buildings often suffer serious damage in the earthquake.Based on the shear wall structure as a breakthrough point,the high damping concrete is applied to the shear wall structure,and with the support of relevant research results of shear wall,putting forward the high damping concrete shear wall with mixed concealed bracings structure system,and experimental study and theoretical analysis are carried out.The main contents and results are presented as follows:1.Performed 14 groups of material experiments with different mix proportion of high damping concrete.In addition,the effects of polymer-cement ratio,latex blend and different fiber on compressive strength and damping ratio of concrete were analyzed,and then the optimal mixture ratio of the high damping concrete was obtained;Performed 9 groups of damping tests of enhanced damping concrete cantilever beam with different polymer-cement ratios,then obtained the relationship between the damping ratio and deformation of the high damping concrete cantilever beam.2.The experimental study on the seismic performance of 4 different types of shear walls under cyclic loading was carried out,and also the failure characteristics,bearing capacity,ductility,hysteretic curve,stiffness attenuation and energy dissipation performance of the proposed shear wall were analyzed systematically.Based on the experimental study,the influence of axial-load ratio and shear-span ratio on seismic performance of shear wall was discussed.The test results indicated that coMPared with the common concrete shear wall with concealed bracings,the seismic behavior indexes and failure mechanism of high damping concrete shear wall are much better,and at the same time,the relationship between the economic indicator and the seismic energy dissipation effect was evaluated in high damping shear wall.3.The experimental study on the seismic performance of two 1/4 reduced-scale models of high damping concrete coupled shear wall with enhanced concealed bracings with concealed steel bracings under cyclic loading has been carried out,meanwhile the nonlinear numerical simulation of the new type coupled shear wall was finished.The test results indicate that coMPared with the common coupled shear wall with concealed bracings,the new type of coupled shear wall showed great improved energy dissipation capacity and better seismic performance,and also the economy can be accepted in engineering.4.A new model of shear wall with concealed bracings macro-element was presented,and a precise and a practical nonlinear finite element analysis method of high damping concrete shear wall with mixed concealed bracings was established referred to experimental data based on ABAQUS program.5.A new low-rise RC shear wall with steel plate and concealed bracings was presented and the seismic performance and nonlinear numerical simulation has been carried on.The test results indicate that coMPared with the common low-rise RC shear wall with concealed bracings,the new type of low-rise shear wall showed great improved ductility and energy dissipation capacity,adequate bearing capacity,plumber hysteretic loops and good seismic performance,and it is one kind of structural element worth recommending to engineering.6.The simplified mechanics model of load-carrying capacity and restoring force modal of different types of shear walls was established,at the meantime a displacement-based deformation capacity design method was then developed for RC shear walls and the calculation procedure for the length of confined boundary zone and its characteristic value of stirrup content was suggested.