Elastic Buckling And Inelastic Load-carrying Capacity Of Thin-walled I-beams With Web Opening

Compared with concrete or reinforced concrete materials,steel has the characteristics of large span,light weight,small section,so steel is widely used in building structures.In many cases,for inspection,maintenance and repair purposes,it is inevitable that the web of the Ibeam will have to be perforated in the actual project.The presence of holes in structural members often redistributes membrane stresses in the plate,complicating the design process and potentially significantly reducing its stability.Especially for thin-walled structures where elastic buckling and load deformation response are closely related,the presence of holes changes the elastic buckling mode and may affect the load deformation and failure mechanism in the limit state.In order to further take into account the mechanical properties,construction benefits and economic benefits of open-hole steel beams,this paper carries out theoretical analysis and numerical simulation for the buckling load of web open-hole plates,and on this basis,experimental research,numerical simulation and theoretical analysis are carried out on the bending stiffness and bearing performance of web-opening Ibeams,and the specific research work and content are as follows:(1)The finite element model of open-hole plates was established by using the finite element software ABAQUS,and the finite element model was verified according to the theoretical calculation formula of non-porous plates,and finally closed-form expressions for approximating the influence of single or multiple rectangular holes on the critical elastic buckling stress of plates in bending,compression,and shearing alone are developed,validated and summarized.The expression forms are based on classical plate stability approximations,and are developed and verified by the parametric studies employing shell finite elements.The expressions serve as a convenient alternative to shell finite element eigen-buckling analysis.The finite element parameter studies have shown that holes may produce unique buckling modes,and the change of hole spacing will reduce or increase the critical elastic buckling stress of the plate.When the spacing between holes is long enough,the single-hole plate buckling stress equation can be used to calculate the porous plate.The validated closed-form expressions and their associated limitations are intended to be versatile enough to accommodate the range of hole sizes and spacings common in engineering practice.(2)Similarly,the proven and effective ABAQUS finite element model was used to analyze,develop,verify and summarize the influence of single or multiple rectangular holes on the critical elastic buckling stress of plates under four composite stress conditions of compression bending,bending shear,compression shear and compression bending shear,and an approximate closed form expression of the stress ratio relationship of the single-hole simple support plate was proposed.The expressions are fitted and verified using a large number of ABAQUS shell finite element models,which serve as a convenient alternative to shell finite element eigen-buckling analysis.Finite element parametric studies have shown that,as in the simple force case,when the hole interval is large enough,the buckling stress of the perforated plate can be replaced by the single-well plate calculation formula.(3)A three-point bending test was carried out on 4 groups of 8 open-hole steel beams and1 unperforated steel beam,and the deformation process and ultimate failure mode of each specimen were recorded during loading.Combined with the load-displacement curve of the specimen,the stress state and failure mechanism of the specimen are analyzed,which proves the important role of stiffening ribs above and below the hole in improving the ultimate bearing capacity of I-shaped steel beams with web openings.By comparing the test results of each group,the influence of three design parameters,namely size of the hole,hole position and stiffening rib setting,on the ultimate performance of steel beams with openings is discussed.(4)Using the finite element software ABAQUS,the finite element model of I-beam with web openings is established,and the ultimate load,failure mode and load-displacement curve of the finite element model are compared with the experimental values to illustrate the effectiveness of the finite element model.Then,the finite element parameter analysis is carried out,and the appropriate finite element model size parameters are selected to make the failure mode of I-beam with web openings be web buckling,and the hole position,hole size,stiffener size and web thickness are adjusted to explore the influence of hole position,hole size,stiffening parameters and web thickness on the ultimate bending bearing capacity and stress situation of I-beam with web openings.