Experimental Study Of The Influence Of Construction Joints On The Seismic Performance Of Edge Joints Of Prefabricated Frames

Since the reform and opening up,with the rapid development of China’s economy,the level of urbanization has increased rapidly,and the promotion of construction industrialization has become the goal and trend of the development of construction industry.The development of prefabricated buildings is the necessary way to realize the industrialization of buildings.Nowadays,domestic and foreign research mainly focuses on the innovation of prefabricated beam-column connection methods to solve the problem of structural integrity,which have greatly innovated the assembly connection system,but due to higher costs and complex operations,the application of new technologies to actual engineering is not something that can be achieved today.Therefore,the research on the prefabricated frame structure of sleeve grouting connection,which is widely used at present,is still of great importance.In addition,since the precast concrete joints inevitably have the interface between the new and old concrete,that is,construction joints,and there are few studies on the influence of construction joints on the integrity of fabricated joints,In this paper,on the basis of summarizing the research results at home and abroad,the research on the influence of construction joints on the seismic performance of fabricated concrete frame joints connected by sleeve grouting is carried out and the theoretical analysis is performed.The main research contents and conclusions in this paper are as follows:Six prefabricated frame edge nodes and one cast-in-place frame edge node were subjected to horizontal low-cycle repeated load tests.The test phenomena,hysteresis curve,skeleton curve,and stiffness degradation of the edge joint specimen are compared to evaluate the seismic performance of the edge joint.The effects of changes in the position of construction joints and the interaction between the axial compression ratio and the construction joints on the ductility and shear capacity of edge joint specimens were analyzed,and the influence of construction joints in shear capacity of edge joint specimens was studied when considering the P-△ effect.The above research analysis shows that all seven test pieces have realized the design concept of "strong columns and weak beams,strong joints and weak components".Compared with the test piece of the whole pouring edge node,the existence of construction joints reduces the bearing capacity,ductility,energy consumption and shear capacity of fabricated edge nodes,but the deformation recovery ability of fabricated edge nodes is better.The location of construction joints affects the seismic performance of the edge joints of fabricated frames.When the construction joint is located at the beam end,the construction joint is more likely to crack.When the construction joint is at one-third of the beam,the seismic performance of the edge joints of the fabricated frame is similar to that of the cast-in-place frame.When the construction joint is located on the beam,the increase of the axial compression ratio reduces the seismic performance of the specimen.For the specimens with construction joints on the columns,the seismic performance is mainly affected by the axial compression ratio,the increase of the axial pressure improves the stress surface of the construction joint,enhances the bite effect of the aggregate and the pin bolt effect,thereby improving the seismic performance of the specimens connected to the columns.For specimens with construction joints located on columns,as the loading level increases,the effect of the P-△ effect on the shear capacity of the edge joint becomes more apparent.The increase of the axial compression ratio also increases the influence of the P-△ effect on the edge nodes of the fabricated frame with construction joints.