In recent years,the prefabricated construction is confronted a new and further opportunity of development.The prefabricated concrete structure is one of the important development directions.Prefabricated concrete technology has the advantages of less dust,less construction waste,high component quality and high construction efficiency.Several earthquake disasters show that the joint design is the key in the design of prefabricated concrete structure,and its performance will affect the strength,stiffness and stability of the whole structure.The rationality of beam-column joint design plays an important role in the overall reliability of prefabricated concrete structure.In order to further promote the application of welded connection in dry connection of prefabricated concrete structures,in this dissertation,the mechanical properties of welded beam-column joints and the optimization of beam-column components of prefabricated concrete structures were discussed.The main research contents are as follows:(1)On the basis of summarizing common connection modes of prefabricated nodes,the advantages and disadvantages of prefabricated concrete structures were analyzed,and the advantages and disadvantages of common connection modes of components were discussed.(2)On the basis of numerical simulation analysis of cast-in-place beam and column connection and prefabricated welded beam and column connection,discrete finite element model of fabricated joints is established and the mechanical properties such as bearing capacity,strength,energy consumption capacity of fabricated beam column joints under low cycle cyclic were analyzed.The seismic performance of fabricated welded joints is analyzed by comparing the nephogram,hysteretic curve and load-displacement skeleton curve of the joints.The results show that prefabricated welded beam column joints exhibit good plastic deformation capacity and seismic performance,and the ultimate bearing capacity of prefabricated welded joints is about 7% higher than that of cast-in-place beam column joints.(3)Parametric analysis of fabricated welded beam-column joints was carried out to study the influence of concrete strength grade,longitudinal reinforcement strength,steel cylinder thickness and axial compression ratio on the seismic performance of fabricated welded beam-column joints.And the influence of parameter changes on the bearing capacity of fabricated welded beam-column joints was analyzed.The results indicate that increasing the strength grade of concrete and the thickness of steel tube can improve the bearing capacity of prefabricated welded beam column joints.Comparative analysis of the economic performance between cast-in-place beam column nodes and prefabricated welded beam column nodes lays the foundation for subsequent optimization of prefabricated beam column components and overall structure.(4)Aiming at a practical prefabricated concrete structure,some prefabricated columns and beams were selected to establish corresponding structural optimization models.The improved dragonfly algorithm is proposed.The elite reverse strategy,golden sine strategy,adaptive inertia weight and random difference mutation strategy were used to improve the dragonfly algorithm.The improved dragonfly algorithm was used to optimize the beam-column components and the overall structure,and the more economical optimal size and reinforcement of prefabricated columns and beams were obtained.This study analyzed the seismic performance of prefabricated welded beam column joints and optimized the prefabricated components and overall structure by using the improved dragonfly algorithm,which can provide a reference basis for the design and structural optimization of prefabricated concrete welded beam column joints. |