Research On Seismic Behavior Of Steel-concrete-steel Composite Shear Wall With Vertical Gaps And Bolt Connection

Steel-concrete composite shear walls are widely used in super high-rise buildings due to its ability to give full play to the characteristics of high lateral rigidity of the concrete structure and good ductility of steel,and the advantage of obtaining higher bearing capacity and deformation capacity with a smaller cross-sectional size.Among them,the steel-concrete-steel composite shear wall has the advantages of partial prefabrication and exemption of formwork engineering.In view of the shortcoming of the large amount of on-site welding work of the traditional steel-concrete-steel composite shear wall,this thesis proposes a new type of composite shear wall with bolted connection and vertical gap between the boundary members and the middle wall.The mechanical properties and seismic performance of this new composite shear wall are studied using experimental investigation,theoretical analysis and numerical simulation.The specific research work includes the following parts:(1)With the axial compression ratio as the research parameter,cyclic loading tests were carried out on 3 steel-concrete-steel composite walls with binding bars,bolt connection and vertical gaps with a scale ratio of 1:3 and a shear span ratio of 1.75.The failure mode of specimen is summarized.The hysteresis curve and skeleton curve of each test piece is analyzed,based on which the bearing capacity,deformation capacity,degradation of strength and stiffness,and energy dissipation capacity are evaluated and compared with traditional shear walls and other walls with vertical or horizontal joints.Combining the test phenomena and the data from displacement meters and strain gauges,the stress distribution and change of the combined shear wall under the action of vertical load and horizontal cyclic load are studied,and the behaviours of the boundary members and the middle walls are explored.The results show that the proposed composite shear wall is a new type composite shear wall with strong deformability,good ductility,and stable bearing performance under cyclic loads;the boundary elementrs and the middle wall bear the horizontal load relatively independently,and the development of stress in the tension zone of the middle wall is affected by the bolt slippage.(2)The finite element analysis software ABAQUS is used to carry out finite element analysis on the test pieces,the selection of material constitutive and definition of interactions and constrains are discussed.The reasons for the large error between the fitted skeleton curves and the test curves are analyzed combining the test phenomenon.In addition,the working mechanism of the horizontal joint is explored.Based on the Multiple Vertical Line Element Model(MVLEM),a simplified modeling of the horizontal joint is proposed,and the slippage of bolt connection is considered by modifying the tensile force-displacement curve of the equivalent vertical line element.The hybrid finite element model with both macro and micro elements is established and found capable of improving the fitting accuracy.The model is used to simulate other jointed shear wall,and the fitting results of the skeleton curves are in good agreement with the test results.On this basis,the working mechanism of the proposed composite wall is summarized.(3)On the basis of the hysteresis curves and skeleton curves obtained by the experiment,using the test fitting method,a simplified skeleton curve model of the proposed steel-concrete-steel composite shear wall with binding rods,bolt connection and vertical gaps is established with the calculation formula of each key points.In addition,the applicability of the bearing capacity calculation method from the Code to the proposed composite shear wall is discussed.Several suggestions on the design and construction of the proposed shear wall are given.