Study On The Overall Stability Of Honeycomb Beams Under The Fixed State Of Both Ends

The castellated beam is a new steel composite with high strength,light weight,beautiful,green,convenient,good economic benefit,etc.For the intermediate/long-span bending steel beams without any lateral support,its material characteristics,such as high strength and light weight,thereof determine that the cross section damage of these steel beams is usually caused by bearing capacity stability loss rather than the strength loss.Therefore,these bending steel beams are usually controlled by overall stability.In recent years,some scholars in China have correspondingly tested and theoretically researched the castellated beam,but such research is mainly focused on the simply-supported and cantilever-supported castellated beam rather than the fixed castellated beam.Moreover,relevant design code for castellated components has not yet been stipulated in China,so the overall stability of the fixed castellated beam will be researched specificall in this paper in order to provide reference for accelerating the promotion of the design code for the castellated beams.In this paper,classical theory is adopted to deduce the formula for calculating the flexural-torsional critical load of the two-end fixed castellated beam under different loads.Specifically,the calculation formula deduction process includes the following steps:firstly,the energy method is adopted to deduce the total potential energy equation of the fixed solid web beam under different loads;secondly,Rayleigh-Ritz method is adopted to solve the overall potential energy equation to obtain the formula for calculating the flexural-torsional critical load of the fixed solid web beam under different loads;thirdly,the volume and inertia moment equivalence principle is adopted to finally obtain the formula for calculating the critical load of the fixed castellated beam.In this paper,the large finite element software(ABAQUS)is adopted for the eigenvalue buckling analysis and the nonlinear analysis of the fixed castellated beam.Specifically,the finite element software is used to calculate the critical loads of the fixed castellated beams respectively supported by round holes and hexagon holes under transverse mid-span concentrated load and transverse uniform load.Therein,the eigenvalue buckling analysis is compared with theoretical formula analysis to verify whether the theoretically-deduced calculation formula is correct;the nonlinear analysis regarding the geometry and material nonlinearity is used for the elastic-plastic analysis.Additionally,the finite element software is also used for analyzing the influence of different factors on the overall stability of the fixed castellated beam.On the basis of the overall stability calculation formula for the dual-shaft symmetric solid web beam,proposed in US design code for steel structures----AISC360-10,the massive data obtained by the finite element modeling and calculation are combined in this paper to propose an overall stability correction coefficient K.Then,the data fitting software lstopt is also adopted for the fitting of the finite element calculation results to obtain K calculation formula in order to finally obtain the overall stability calculation formula for the fixed castellated beam supported by different holes.Finally,the calculated value of the new formula is compared with that of the finite element software(ABAQUS)to verify the safety applicability of the new formula.The main innovations of this paper as following:①By using the results that were calculated by the finite element software ABAQUS,verify the calculation formula of the stability of the fixed-castellated beam among two ends of equal moment,transverse uniformly distributed load and mid span concentrated load.②By the using of the finite element simulation of castellated beam by ABAQUS software,amply analyzed the influence of the factors of the load,the shape of hole,the pitch ratio and the high ratio of hole on the stability of the fixed-castellated beam.In the engineering design,it provides reasonable suggestions for these variables which affect the stability of the fixed-castellated beam.③Based on the formula Mx≤ φbMcr,raised by AISC360-10,which is global stability of a compact solid beam with double negative moments in both ends.Introduced an overall correction factor K,Established the calculation formula of K by the data fitting software.Finally,a simple and practical formula KMx ≤φbMcr to calculate the overall stability of the castellated beam was found.