Study On Equivalent Stiffness Of Semi-rigid Connection Castellated Beam Steel Frame

The semi-rigid connection castellated beam steel frame structure is easy to assemble,green and energy-saving,castellated holes can pass through pipelines,reduce the floor height of the structure,and has good economy and application prospects.Semi-rigid connection and castellated beam work together,which can improve the working performance of the structure,not only protect the connection more effectively and prevent its brittle failure,but also give full play to the mechanical properties of castellated beam and relieve the stress concentration at the hole angle of castellated hole.However,at present,there is little research on the semi-rigid castellated beam steel frame,and the influence of castellated holes on the stiffness of the semi-rigid castellated beam steel frame is still unclear,and there is no accurate analysis method.This paper mainly studies the rigidity and mechanical performance of the hexagonal castellated hole and the thickness of the end plate on the structure,and puts forward a reasonable structural analysis method,which provides a certain reference for the design and application of the castellated beam steel frame with semi-rigid connection.In this paper,the effects of hole ratio,hole spacing and end plate thickness on the stiffness of honeycomb beam steel frame connected by end plates are studied.According to the energy method theory and Simpson formula,the calculation formula of equivalent bending stiffness of honeycomb beam considering semi-rigid influence is derived.Based on the static test of honeycomb beam-column connection with end plate connection,the finite element model of the test specimen is established by ABAQUS,and its accuracy is verified by comparing with the test results.The honeycomb beam-column connection models of 84end-plate connections are established by taking the factors of honeycomb hole opening rate,hole spacing and end plate thickness as parameters,and the influence of the above factors on the equivalent bending stiffness of honeycomb beams is analyzed to verify the accuracy of the calculation formula of equivalent stiffness of honeycomb beams.On this basis,using the stiffness matrix analysis method of semi-rigid connection steel frame and combining with the equivalent bending stiffness formula of honeycomb beam,an analysis method of honeycomb beam steel frame suitable for semi-rigid connection is proposed.Through finite element analysis of honeycomb beam steel frame with end plate connection,the effects of different opening ratio,end plate thickness and connection type on its static performance such as lateral displacement value,interstory displacement angle and internal force distribution are studied.The research results show that compared with other forms of steel frames,the castellated beam steel frame with end plate connection has larger mid-span bending moment and larger column foot bending moment,which better optimizes the internal force distribution of the structure.The thickness of the end plate and the ratio of diameter to height are important influencing factors: with the increase of the thickness of the end plate,the equivalent bending stiffness of the castellated beam increases,and the lateral displacement value and interlayer displacement angle of the castellated beam steel frame decrease;With the increase of diameter-height ratio,the equivalent bending stiffness of castellated beam decreases,and the lateral displacement value and interlayer displacement angle of castellated beam steel frame increase.The thickness of the end plate should be designed to be greater than 8mm,the diameter-height ratio of the castellated hole should be less than 0.7,and the column foot size should be appropriately increased.According to the analysis results of castellated beam steel frame with end plate connection in this paper,reasonable design suggestions are put forward to provide reference for engineering application.