Analysis Of Mechanical Properties Of Frames With Cantilevered Beam Segment Embedded Joint Based On Joint Simplification Theory

At present,the residential industry of steel structure is developing rapidly in China,and scholars at home and abroad study more and more on steel structure beam-column joints.The joints of traditional steel structure beam-column have many disadvantages,such as many welds,the on-site welding construction is difficult and the brittle failure is easy to occur under earthquake loads.In response to these problems,scholars at home and abroad have proposed prefabricated plastic hinge out-shift joints,which have the advantages of high degree of industrialization,convenient construction,superior seismic performance and so on.The prefabricated embedded joint with cantilever beam segment is one of this type of joints.In the finite element numerical calculation of high-rise frame,if solid elements are used for modeling,the number of model elements is very large,the interactions are complex,and the analysis process is time-consuming and labor-intensive.In order to improve the efficiency of finite element numerical calculation of multi-storey multi-span steel frame with cantilever beam segment embedded joints.In this paper,the simplified theoretical model of joint was used to carry out static and pseudo-static analysis of four kinds of embedded joint with cantilever beam segments and corresponding one-story and one-span steel frames using the finite element software ABAQUS,the calculation results of joint simplified model and joint solid model were compared and the calculation results of frame simplified model and frame solid model were compared.The feasibility and reliability of joint simplified theoretical models used to calculate the joints and frames with cantilever beams were analyzed.The analysis results show that: When the joint simplified model is used to analyze the static and quasi-static analysis of the joints with cantilever beam segment,the fitting effect between the joint simplified model and the joint solid model is better if the plastic hinge is shifted outwards;if the plastic hinge is not shifted outwards,the fitting effect between the joint simplified model and the joint solid model is slightly worse.When the frame simplified model is used for static and quasi-static analysis of the frame with cantilever beam segment,regardless of whether the plastic hinge is displaced or not,the fitting effect between the simplified frame model and the solid frame model is good,and the calculation results have a certain degree of accuracy.In order to study the influence of different joint splicing forms of cantilever beam segment on the seismic performance of multi-storey and multi-span steel frames,in this paper,four kinds of steel frames with cantilever beam segments embedded joints of3-story 1 span,6-story 2 span and 9-story 3 span were designed.Through static and pseudo-static finite element numerical calculation of four kinds of joint steel frames,the influence of different joint forms on the seismic performance of steel frames was analyzed.The results show that: The seismic performance of the embedded reinforced frame with cantilever beam segment is the best,the seismic performance of the embedded frame with cantilever beam segment and the embedded bolt-welded hybrid frame with cantilever beam segment is slightly worse,and the seismic performance of the traditional beam-column connected frame with cantilever beam segment is the worst.Based on the embedded reinforced joint with cantilever beam segment,two simplified steel frames of 3,6 and 9 layers with different structural parameters were designed by changing the width and thickness of the overhang flange of cantilever beam segment.The effects of the width and thickness of the overhang flange on the mechanical properties of embedded reinforced steel frames with cantilever segments were studied by static analysis and quasi-static analysis of two simplified models of steel frames with variable parameters.The results show that: the variation of the width and thickness of the overhanging flange of the cantilever segment has no obvious effect on the bearing capacity of the 1-story structure of the embedded reinforced multi-storey steel frame with the cantilever segment.The bearing capacity of the top storey structure of the frame is slightly improved,the bearing capacity of the standard storey structure has been improved most significantly.When changing the width of the extended flange to increase the width-thickness ratio to 8.96 or changing the thickness of the extended flange to increase the width-thickness ratio to 5.31,the seismic performance of the embedded reinforced multi-storey steel frame with cantilever beam segment is improved most obviously.During the parameter design of the embedded reinforced steel frame with cantilever beam segment,the thickness and width of the extended flange can be controlled by controlling the width to thickness ratio of the extended flange of the cantilever beam segment or the area of the extended flange of the cantilever beam segment.It is recommended that the width to thickness ratio of the extended flange be between 8.25 and 9.68,or the ratio of the extended flange area to the middle beam segment flange area be between 1.14 and 1.29.