Local Stability Analysis Of Castellated Beam Web And Setting Of Stiffeners

With the characteristics of light weight and high strength,material saving,attractive appearance and convenient crossing of pipelines,honeycomb steel members are widely used in multi-story buildings and large-span space structures.Because of the web openings,the castellated beam is divided into two parts,the bridge plate and the pier plate,which change the stress distribution mode of the original solid-web section.What's more,the shape and the supporting side of the plate have changed,and the sectional stress distribution mode becomes much more complicated.At present,the researches of honeycomb member at home and abroad are mostly concentrated on overall performance,while the research on local buckling of the honeycomb webs is relatively few.In this paper,we apply theoretical analysis,experimental research and finite element simulation to research the pure bending and buckling of castellated beam web with hexagonal openings.Three different castellated beams are subjected to quarter-point static loading test.After observing and comparing the damage morphology and load-displacement curves of these castellated beams,we research on the local stability and overall performance of beams' webs.The results show that under the pure bending load,the buckling mainly occurs in the bridge plate above the openings,and also in the pier plate among the openings.Reducing the depth-thickness ratio of the web and setting stiffeners can improve the web buckling performance and the overall performance of castellated beam.Through theoretical analysis and finite element simulation of pure bending,we study the influence rule of web's depth-thickness ratio,opening ratio and pier plate's aspect ratio on the local stability of castellated beam web.As the depth-thickness ratio of web decreases,the buckling load of the castellated beam progressively increases,while the ultimate flexural capacity and ultimate corner are decreasing gradually.With the increase of opening ratio,the buckling load of castellated beam and the stability of the bridge plate enlarge,while the stability of the pier plate decreases.However,the overall performance of the castellated beam reduces,and the ultimate flexural capacity decreases with the increase of opening ratio.With the decrease of aspect ratio of pier plate,the buckling load of castellated beam and ultimate corner both decrease.The effect of stiffeners on the local stability of webs under pure bending is studied.We make linear and nonlinear analysis of the castellated beams,such as bilateral transverse stiffener setting,unilateral transverse stiffener setting,unilateral longitudinal stiffener together with bilateral transverse stiffener setting,and bilateral longitudinal stiffener together with bilateral transverse stiffener setting.Then,we analyze the linear buckling load,nonlinear buckling load and overall performance of castellated beams with different stiffener settings.By comparing different setting methods and analyzing various performance indexes of castellated beam,it can be concluded that:Reasonable setting of transverse stiffener can better prevent the pier plate of castellated beam buckling.Through comparing the different transverse stiffeners settings,we conclude that the setting of stiffeners with two openings at intervals and the continuous setting of stiffeners are much better.When the longitudinal stiffener and transverse stiffener are set together,the local buckling of bridge plate of castellated beam can be well prevented,and at this moment the castellated beam is at strength fracture under the action of bending moment.By comparing and analyzing the different settings of stiffeners,it is concluded that the longitudinal stiffener setting is better when the transverse stiffeners are set with two openings at intervals and set continuously.In this paper,we come up with the optimal stiffener setting of castellated beam under pure bending load,which provides a reference for the application of castellated beam in engineering.