Study On Seismic Behavior Of Assembled Shear Wall With Vertical Energy-consuming Joints

Assembled shear wall is the main lateral resistance component widely used in high-rise buildings.Both the self-weight and lateral stiffness of the assembled shear wall are large while the natural vibration period of the structure is short,which makes its earthquake response large under strong earthquakes.These characteristics make it difficult to repair the damaged shear walls.Assembled shear wall structure is an important structural form in the process of building industrialization in China.Its horizontal joints as well as vertical joints are the key factors affecting the seismic performance of the structure.In order to improve the seismic performance of the assembled shear wall,this paper puts forward a kind of assembled shear wall with vertical energy-consuming joints.The horizontal joints are connected by slurry anchors,and vertical joints are opened along the height of the shear wall and soft steel dampers are set to increase the deformation and energy dissipation of the structure.The soft steel damper is installed with a dry connection and is easily replaced after damage,while reducing the damage of the main wall.Therefore,this paper analyzes the seismic performance of assembled shear walls with vertical energy-consuming joints by numerical simulation and theoretical research,and carries out parametric analysis of the influencing factors of seismic performance.The main research contents and achievements include:1.Based on the finite element software ABAQUS,the simulation methods of hysteretic behavior of reinforced concrete shear wall are analyzed,including the equivalent simulation of bond-slip between reinforcement and concrete,the selection of constitutive parameters of CDP model and the calculation method.The validity of the calculation method of the constitutive parameters is verified by the existing experimental data.The results show that the hysteretic constitutive model of reinforcing bars with reduced stiffness under reloading as well as the stress-strain relationship of concrete in accordance with the Chinese Code with the peak compressive strain recommended by the European Code can yield accurate results.The length of the damage factor of concrete should be 0.90-0.95,and the recovery factor of compressive damage should be 0.3-0.6.Using the above constitutive parameters,the elastic-plastic behavior of reinforced concrete middle walls or high walls with aspect ratio greater than 1.5 can be predicted accurately under hysteretic loading.2.An energy-dissipating soft steel damper for vertical joints of shear walls is designed.The yield mode,yield shear force and vertical stiffness of the damper are analyzed by finite element method.The results show that the damper has good energy dissipation capacity.On this basis,the numerical models of a vertical through-slot shear wall and an assembled shear wall with vertical energy-consuming joints are established by applying the existing constitutive parameter calculation method,and the low-cycle reciprocating loading analysis is carried out.The seismic performance of the specimens is compared comprehensively from the aspects of failure mechanism,hysteresis curve,skeleton curve,bearing capacity and deformation,and energy dissipation capacity.The research results show that the bearing capacity and stiffness of the assembled shear wall with vertical energy-consuming joints are improved,the damage displacement is increased by 41%,the cumulative energy consumption is increased by 47%,and the seismic performance is improved.3.Parametric analysis is made on the key factors affecting the seismic performance of assembled shear wall with vertical energy-consuming joints,such as axial compression ratio,concrete strength grade,vertical stiffness of soft steel dampers,yield shear force and arrangement angle of dampers.The results show that the optimum axial compression ratio is 0.2-0.3,the bearing capacity increases with the increase of concrete strength grade,while the deformability is opposite.The strength grade of concrete should not be greater than C60.The thickness and cross-section shape parameters of soft steel dampers affect the vertical stiffness and yield shear force.It is necessary to ensure that the damper's vertical stiffness and yield shear force are moderately designed to achieve an ideal failure mechanism.The arrangement angle of soft steel dampers should be considered by considering the design requirement of vertical joint shear wall and the number of dampers.When the number of dampers is small,the energy consumption can be increased by oblique arrangement.When the number of dampers is large,the angle should not be greater than 30 degrees.4.The mechanical properties of the assembled shear wall with vertical energy-consuming joints are studied by theoretical analysis combined with specific examples.The damper yield mode and parameter design requirements are determined,and the vertical stiffness,yield shear force and end bending moment calculation formula of the mild steel damper are given in this chapter.Based on the continuous link method,the horizontal displacement,elastic equivalent bending stiffness and anti-side stiffness reduction coefficient expression of the assembled shear wall with vertical energy-consuming joints are derived,and the vertical energy-consuming joint assembly shear is proposed.The calculation formula of ultimate bending capacity of the force wall is compared with the finite element calculation results.The results show that the theoretical formula is 10%~20% smaller than the finite element result,and the theoretical formula of the bearing capacity is used to be safe.