Study On Seismic Behavior Of The Superimposed Shear Wall With Increasing Connecting Bars At The Horizontal Joints

The superimposed slab shear wall structure studied in the paper is a kind of semi-precast reinforced concrete shear wall structure. The precast part of the wall panel is composed of two precast panels and the connecting truss bars. Core concrete was cast and composite member was formed after precast part installed. The superimposed slab shear wall combines the features of the precast shear wall and the cast-in-place shear wall. It suits well with China’s national conditions because of its better integrity and low installation accuracy request. The seismic performance experiment of the superimposed slab shear wall conducted previously by our research group showed that the above wall part shook around the straight joint in the horizontal connection as an overall mass under cyclic loading. The deformation capacity and ductility of the structure were worse than those of the precast wall. The purpose of being equal to the cast-in-place shear wall could not be reached. Later, the research group designed two specimens with stronger connecting steel in the horizontal joint and conducted the low cyclic reversed loading test. The results showed that the purpose could be reached by designing the horizontal connection with stronger strength. However, the amount of specimens was little and the vertical axial force was not applied.In order to further study the seismic performance of the superimposed slab shear wall with stronger connecting steel in the horizontal connection, three pieces of superimposed slab shear walls with shear span ratio at 2.38 and one piece of cast-in-place concrete shear wall were conducted under the low cyclic reversed loading test. The main experiment parameters contained the moment super coefficient and the axial compression ratio. The results indicated that plastic hinges occurred in the horizontal connections and the wall for the specimen with small moment super coefficient. But the plastic development in the panel was more serious. Plastic hinges transferred from the horizontal connections between wall and foundation to the wall itself for the specimen with large moment super coefficient. With the same moment super coefficient, the larger axial compression ratio was, the more seriously the plastic developed in the wall. The seismic behavior of the superimposed slab shear walls was similar with the cast-in-place reinforced concrete walls. The peak load o was larger of the superimposed shear with the larger moment super coefficient. The ultimate drift ratios of the superimposed slab shear walls were 1/46-1/67, the deformation performance met the regulation requirement.Based on the test, numerical investigation of the specimens was conducted using ABAQUS. The results met well with the experiment indicating that the finite element models could predict the mechanical behavior and damage pattern of the specimens well.Based on the typical residential structure, the necessity of strengthening the connecting steel in the horizontal connections of the superimposed slab shear wall in specific structure is verified.