Experimental Study On Seismic Performance Of Variable Cross-section Rib Plate Connection Between Double Skin Composite Wall And Steel Beam

Double-skin composite wall is a new type of shear wall used in high-rise buildings.Compared with traditional reinforced concrete shear walls,it can make full use of the material properties of steel and concrete,because the inner concrete can be restrained through the outer steel cavity which makes concrete in a state of three-way compression,and the inner concrete also supports the outer steel cavity to prevent it from buckling before yielding.Because of this characteristic,the double-skin composite wall has the advantages of high bearing capacity,strong deformation capacity,and small wall thickness.Based on the above advantages,the double-skin composite wall will be a structural system with great development potential.For a new structural system,it is necessary to study the connection mode.Based on the existing research results of rib-type wall-beam connection,this paper studies variable cross-section rib plate connection between double skin composite wall and steel beam with weakened cross-section that may occur in actual engineering.The following studies are carried out by means of low cyclic loading experiment,finite element simulation and theoretical analysis:(1)Taking the variable section size of the rib and the eccentricity of the rib as the research parameters,the quasi-static tests of three groups of full-scale variable cross-section rib plate wall-beam connections are carried out.The effects of the research parameters on the failure mode,hysteretic curve,skeleton curve,ductility,energy consumption and stiffness degradation of the specimens are analyzed from the macro aspect,and the strain distribution among the specimens with different parameters is analyzed from the micro aspect.The test results show that the variable cross-section rib plate wall-beam connections are all tearing and penetrating at the variable section of the rib plate when they fail,and the end plate is pulled out from the boundary column of the wall.The hysteresis curve of each specimen is in the shape of a fusiform.The maximum deformation of the connection is between 0.0283 rad and 0.0433 rad,the bearing capacity is between 327.77 k N·mand 439.74 k N·m,the ductility coefficient is between 1.41 and2.25,and the maximum equivalent viscous damping coefficient of the joint is between0.192 and 0.367.The comparative analysis shows that the reduction of rib width and increase of rib eccentricity can improve the mechanical performance of the specimen.(2)The finite element model of the test specimen was established by the finite element analysis software ABAQUS.The damage and failure of the specimen were considered through the concrete plastic damage constitutive relation and the steel ductility damage constitutive relation based on stress triaxiality.The accuracy and reliability of the model are verified by comparing the failure modes and seismic performance of the test and simulation results.Based on the comparison results,the benchmark model is determined,and the parameters of the variable cross-section rib plate wall-beam connections are analyzed,including the rib cross-section size,the rib cross-section eccentricity,the rib extension length,the rib shoulder extension length,the rib variable cross-section concave corner radius and the wall axial compression ratio.Each parameter corresponds to four analog models.(3)Combined with the test and simulation results,the full section elastic calculation formula of variable section rib plate is proposed,and the rib plate design method of the variable cross-section rib plate wall-beam connections is proposed based on the existing design methods.