Study On Mechanical Behavior Of Precast Concrete Special Shaped Column To Steel Beam Hybrid Frame Joint

In recent years,great efforts have been made to develop prefabricated buildings in China,and the construction industry in China is undergoing the transformation of green building and construction industry.As an important carrier of building industrialization,prefabricated buildings will enter a new period of development.China's annual residential completion area of about 800 million square meters,the use of frame structure of residential construction is increasing.In the frame structure,the concrete special shaped column is used to replace the traditional rectangular section column,which avoids the protruding of the frame column in the room,increases the indoor space and is convenient for interior decoration.Concrete special shaped column structural system has good building function,but there is also the shortcoming of insufficient shear bearing capacity of panel zone.Under this background,this paper presented a precast concrete special shaped column to steel beam hybrid frame structure.Considering the stress transmission,construction efficiency,etc.,this paper designed connection and proposed in the panel zone configuration X-shaped steel plates and X-shaped reinforced two ways to enhance the shear bearing capacity.Through full-scale test and finite element simulation,the mechanical behaviors of the frame joints and the shear bearing capacity of the panel zone were studied deeply.The main works and achievements are as follows:(1)The failure process and failure mode of the specimens were obtained by the low cycle repeated loading test of precast concrete special shaped column to steel beam hybrid frame joints.The seismic resistance indexes such as the hysteresis curve,the skeleton curve,the bearing capacity and the stiffness degradation of the joint were analyzed.The shear deformation and strain distribution in the panel zone were also analyzed.The test results showed that all the specimens were joint shear failure,and the X-shaped steel plates and the X-shaped reinforced effectively increased the shear bearing capacity of the panel zone and improved the failure characteristics of the specimens.The connection is reasonable and reliable.(2)The finite element software ABAQUS was used to numerical simulate the precast concrete special shaped column to steel beam hybrid frame joints.The constitutive relations of concrete and steel were set by concrete plastic damage model and steel double-break line model respectively.The simulation results were in good agreement with the experimental results,which proved that the finite element model was reasonable and effective.Variable parameter analysis based on the finite element model,the parameter was the thickness and width of the X-shaped steel plate.The analysis results showed that the increase of the thickness and width of X-shaped steel plate will increase the shear bearing capacity of precast concrete special shaped column to steel beam hybrid frame joints.Variable parameter analysis provided reference data for subsequent theoretical analysis.(3)Based on the experimental and numerical simulation results,this paper compared the mechanical mechanism and design method of common shaped column joints,and analyzed the shear mechanism of prefabricated concrete special shaped column to steel beam hybrid frame joint with X-shaped steel plate in the panel zone.The formula for calculating the shear bearing capacity of prefabricated concrete special shaped column to steel beam hybrid frame joint with X-shaped steel plate in the panel zone is proposed and the validity of the formula is verified.The shear bearing capacity formula proposed in this paper is relatively accurate and has a certain safety reserve.