Study On Seismic Performance Of Assembled Special-shaped Column Frame Structure Connected By Top And Bottom Angle Stee

With the advancement of China’s construction industrialization,the construction industry has made sustained progress in terms of technological progress and construction scale.However,the traditional construction industry has high resource consumption,heavy environmental pollution,and low industrialization level,which is not suitable for the requirements of green and low-carbon sustainable development.However,prefabricated building are energy-saving,environmentally friendly,efficient and conducive to industrialization,which is the only way to upgrade the construction industry and high-quality development in the new era.Beam column joints are the top priority of frame structures,and the connection of prefabricated components is the decisive factor affecting the seismic performance of prefabricated building.To ensure the integrity of the structure,cast-in-place is often used to connect the components of prefabricated concrete structures in multi-story and high-rise buildings;Single story and two to three story houses in village and town buildings have small heights and low seismic responses.Using top and bottom angle steel and bolts to assemble prefabricated concrete beams and columns on site can minimize on-site wet operations,save energy,labor,and reduce environmental pollution,making them a better construction method for village and town buildings.The prefabricated frame connected by top and bottom angle steel,although the overall structure is not as good as cast-in-place,can dissipate energy due to the deformation of the angle steel during earthquake,so this semi rigid node can meet the seismic performance requirements.This article adopts a combination of experimental and numerical analysis methods to study the seismic performance of prefabricated frame joints connected by top and bottom angle steel.The specific work includes:1.Two full-scale models of prefabricated special-shaped column concrete frame nodes connected by top and bottom angle steel were designed and manufactured.Through low cycle repeated loading tests,the failure mechanism and mechanical properties of the nodes were studied,and compared with a group of cast-in-place frame nodes.2.Propose a modeling method for assembled special-shaped column nodes connected by top and bottom angle steel in ABAQUS finite element software,based on the experimental load displacement skeleton curve,to verify the correctness of the modeling method.3.Conduct numerical simulation analysis on assembled special-shaped column joints with top and bottom angle steel connections of different parameters in actual engineering,and study and summarize the seismic performance of this joint.4.The simplified analysis model of the prefabricated special-shaped column frame node of the top and bottom angle steel is proposed,and combined with the principle of equivalent substitution and correction of the special-shaped column section,it can be used for the seismic analysis of the overall structure in SAP2000.5.Conduct static elastic-plastic analysis and nonlinear time history analysis on the assembled integral structure,study the failure modes of the entire structure,determine the distribution of internal forces in the structure,and summarize the differences in seismic performance between the structure and the cast-in-place frame structure.The research results indicate that:1.The prefabricated special-shaped column frame nodes connected by top and bottom angle steel have the same beam hinge failure mechanism as the cast-in-place nodes.The plastic hinge at the beam end of the prefabricated node moves outward towards the mid span direction due to the protection of the steel plate.When the plastic hinge at the beam end appears,the column damage is smaller than that of the cast-in-place node.After the test loading is completed,there is no significant deformation of the angle steel and screw.2.The dry connection of top and bottom angle steel with bolts presents a semi rigid characteristic of prefabricated nodes due to the relative rotation between beams and columns and the sliding effect between bolts and hole walls.The stiffness is smaller than that of cast-in-place nodes,and the ductility coefficient,energy consumption capacity,and ultimate bearing capacity are slightly better than that of cast-in-place nodes.3.After the bolt holes are compacted,the mechanical properties of the prefabricated frame nodes connected by the top and bottom angle steel are almost the same as those of the cast-in-place nodes,and it can be considered that the prefabricated nodes with sealed holes are "equivalent to cast-in-place".4.The prefabricated special-shaped column frame structure connected by top and bottom angle steel has a different overall internal force distribution from the cast-in-place structure.The reinforcement of the prefabricated beams and columns should be determined based on the internal force analysis results of the semi rigid node frame.The failure mode of the structure is a typical "beam column hinge mixed yield mechanism",and the stiffness and base shear force in the elastic stage are smaller than the cast-in-place structure under the same conditions,while the interlayer displacement angle is greater than the cast-in-place structure.