Study On Seismic Behavior Of Composite Coupling Steel Frame Shear Walls

Composite coupling steel frame shear wall(SFCW)is a new structural system composed of steel coupling beam and composite steel frame shear wall.It combimes the advantages of concrete and steel materials during earthquakes,obtaining high axail load ratio,high ductility and excellent energy disspation capacity as small thickness as possible.According to code of AISC 341-2010 and JGJ138-2016,The seismic design method of SFCW based on the 30% CRD of steel coupling beam and composite shear wall yielding is proposed and one 1/4 scaled 5 storey specimen was tested until to failure.The behavior of specimen,including lateral load-displacement relationship,ductility,stiffness degradation,energy disspation,failure mode,interstory drift and shear deformation of steel coupling beam were examined.Test reslts indicated that SFCW structure presents an excellent seismic behavior.The yielding mechanism of the structure was steel coupling beam to shear wall,and the shear plastic deformation capacity were sufficient after shear wall yielding,fully embodied the theory of double-line to defend earthquake by introducing shaped steel and changing sectional dimension of steel coupling beam.The cracks of shear wall equally distributed along the structure height and intensive cracks were not observed at joint of steel and wall.The damage mode of the structure were fracture damage of the welded joint betwwen the steel coupling beam web and stiffening rib,the large plastic deformation of shaped steel column flange and the concrete of shear wall base corner crushing.It was confirmed that the finite element modeling and method is a reliable and accurate technique to capture the main mechanical characteristical of specimen based on experimental results.As a result,15 FE models were established to investigate the influences of key parameters,such as axial load ratio α,sectional steel ratio ρs and flexure shear ratio Mp/Vp on the seismic performance of SFCW.The results indicate that the axial load ratio has little influence on the lateral load capacity,initial stiifness and energy dissipation capacity.In order to avoid the adverse effect on ductility,axial load ratio should be limited to the upper level,about 0.2 for the normal value or about 0.48 for the design value.Although increasing the sectional steel ratio of shear wall can most effective increase the lateral load capacity and energy dissipation capacity,an upper limit about 8.0% is its optimum value for avoiding brittle failure.The ductility and energy dissipation capacity of plastic shear deformation is superior to plastic bent deformation.The design of steel coupling beam should comply with shear capacity weaker than bending capacity.To ensure the steel coupling beam fully exert shear plastic deformation capacity,the clear span shoud be between 1.0 M_p/V_p to 1.5 M_p/V_p.