Finite Element Analysis And Experimental Study On New Type Vertical Connections Of Precast Composite Shear Walls

In recent years,industrial housing is in the stage of continuous sustainable development,which is consistent with the theme of sustainable development in China.Prefabricated composite shear wall is a part of residential industrialization.Along with the progress of urbanization in China,the modern style high-rise residential building is gradually more and more.Prefabricated composite shear wall begins to be applied to engineering.In this case,based on the study of prefabricated composite shear wall,a new type of vertical connection of the prefabricated composite shear wall structure system is proposed.Notches are set at left and right bottom of the prefabricated composite shear walls to use U-shaped closed reinforcement connections,or move the concealed bracing down and change the cross angle to 90 degrees to enhance the node connection,in order to reduce the amount of concealed bracing.And the prefabricated composite shear wall can keep better seismic performance.The key problem of improving the structural performance of precast concrete shear wall is strengthening the connection between the prefabricated components,including vertical connections and the connection between the adjacent walls.The reliability of these connections affect the overall performance of the structure and seismic quality.Therefore,before the further promotion of the prefabricated composite shear wall system,a reliable connection must be developed.The new vertical connection method proposed in the paper is to strengthen the vertical connection,provide theoretical basis for the engineering.In this article,through the combination of experiment,theory and finite element analysis,the new type of vertical connections of prefabricated composite shear wall system was systematically analyzed,the main research contents are as follows:(1)Quasi-static tests of three shear walls were carried out which are a cast-in-place shear wall,a prefabricated composite shear wall with u-shaped closed reinforcement connection and concealed bracing,and a prefabricated composite shear wall which concealed bracing moves down and the cross angle was changed to 90 degrees.The bearing capacity,the damage characteristics,the hysteresis property,the skeleton curves,the displacement ductility,the rigidity degeneration and the energy dissipation capacity of three shear walls were analyzed and compared.From the test results,it can be seen that the bearing capacity of cast-in-place shear wall and all kinds of seismic performance indexes are superior to the precast composite shear wall.The damage pattern and crack forms of three walls are nearly the same,and the bearing capacity of the prefabricated composite shear wall with u-shaped closed reinforcement connection and concealed bracing is similar to that of the cast-in-place shear wall.The performance of the prefabricated composite shear wall which concealed bracing moves down and the cross angle was changed to 90 degrees decreased slightly,but it can save a lot of steel.(2)The ABAQUS finite element is used to simulate the three walls.In order to better simulate the mechanical behavior of the new and old concrete at the horizontal seam,the nonlinear spring element is used to deal with the contact.The simulation results of the finite element model under monotonic horizontal load agrees well with the experiment results.The conclusion shows that the finite element model and the selected parameters are reasonable and reliable.(3)Under the premise of proving the reliability of the finite element model,the bearing capacity,stiffness and deformation of the new vertical connection prefabricated composite shear wall are demonstrated by changing the axial compression ratio,the dark bearing steel ratio and the concealed bracing.The simulation results show that the bearing capacity and rigidity increase with the increase of axial compression ratio,and too big axial compression ratio is not conducive to the seismic resistance.The increase of the steel ratio of the concealed bracing can improve the peak capacity effectively,but it has almost no effect on the initial stiffness.Reasonable dip angle of concealed bracing can consume more energy and improve the seismic performance.