Experimental Comparative Study On Cross-shaped Shear Wall-floor Slab Joint

Superposed shear wall is one of the main development directions of prefabricated concrete building system and has been widely used in China,because of its energy conservation,environment protection,safety,high efficiency and so on.Consulting a large number of domestic and foreign literature,it is found that there are many performance problems of joint in prefabricated concrete structures,such as less research on the mechanical properties of shear wall floor joints.In order to better improve the prefabricated concrete building system and meet the requirements of nowadays building industrialization.Based on the experiment and numerical simulation of mechanical performance of cross-shaped superposed shear wall-floor slab joint（DHB-1）specimen and cross-shaped cast-in-situ shear wall-floor slab joint（XJB-1）specimen,this paper compared the failure mode,load-displacement curve,bearing capacity and other mechanical performance of the two specimens;meanwhile,verified the rationality and scientificity of the model.Based on the numerical simulation,this paper discussed the influence of the presence or absence and the layout direction of floor truss reinforcement on the mechanical performance of the superposed shear wall-floor slab joint with building the model of DHB-2 specimen（with the truss reinforcement removed）and DHB-3 specimen（with the floor truss reinforcement arranged horizontally）,which is analyzed in detail from load-displacement curve,concrete damage and reinforcement stress.The main conclusions are as follows:（1）The crack distribution and extending of DHB-1 specimen and XJB-1specimen are basically the same,which mainly concentrated at the tensile surface of the floor around the joint,and the concrete was crushed and fell off in the compression surface of the floor.Besides,the wall and the joint core were not damaged,and the bearing capacity and deformation capacity of the specimen was good,which means the structural form of the shear wall-floor slab joint is rational,conforming to the design concept of "strong node and weak member".（2）Around the joint of DHB-1 specimen,the crack can penetrate the precast part and cast-in-situ part along the thickness direction of the floor,and there was no separation and dislocation during the experiment between the precast floor and cast-in-place floor,which means the structural form of the floor of DHB-1 specimen is rational,and can ensure its integrity.（3）Comparing the load-displacement curve of XJB-1 specimen and DHB-1specimen,the yield load and the peak load of DHB-1 specimen were increased,but had a lower ductility,and the bearing load decline faster after reaching the peak load.（4）The comparison between the numerical simulation and the experiment shows that the mechanical properties such as load-displacement curve,the failure process and characteristics and bearing capacity of the specimen are basically consistent,which shows that the settings such as interaction and boundary conditions are reasonably in the model,and the concrete constitutive model adopted is correct,which verifies the scientificity and reliability of the numerical simulation.（5）Comparing the result of numerical simulation of DHB-1 specimen and DHB-2 specimen,found that the stiffness and bearing capacity of the superposed shear wall-floor slab joint specimen was improved by arranging the trusses reinforcement longitudinally（perpendicular to shear wall）.Comparing the result of numerical simulation of DHB-2 specimen and DHB-3 specimen,found that the mechanical performance of the superposed shear wall-floor slab joint specimen was less influenced while arranging the trusses reinforcement horizontally（parallel to shear wall）.