Study On Fatigue Properties Of Circular Hole Simply Supported Castellated Steel Beams

As a new type of steel component,castellated structure has the advantages of high material strength,economical structure and easy to cross pipelines,and is widely used in various projects.Especially under the prem;ise of saving self-weight,the bending rigidity of the section is increased,and the flexural capacity of the section is improved,and it is used as a bending member or a large-span component for a factory building,a multi-tall building and a large-span structure.Countries such as Japan,Europe and the United States have incorporated the design of castellated components into the specification.However,in steel structure highway bridges,steel structure crane beams or other structures subjected to dynamic loads,due to the high number of dynamic load cycles,which involves the fatigue performance of the structure,solid steel is used for safety reasons.Components are extremely cautious for the application of castellated steel components.Fatigue is an important factor that restricts the development of steel structures.Especially for welded steel structures,fatigue damage has become a disadvantage that seriously affects the safe use of structures.Since the plastic deformation is minimal before the fatigue failure occurs,there is no obvious sign of damage,and the damage is extremely great.At present,the research on castellated components is more in-depth at home and abroad,but in the current steel structure design specifications of various countries,the fatigue design method for castellated components has not been found.Due to the lack of relevant research on the fatigue problem of castellated components,many limitations have been imposed on the engineering application of castellated steel components,which need to be studied and solved.Based on the consideration of this problem,this paper selects the circular-hole simple-supported castellated steel crane beam as the research object,and uses the finite element software to establish the solid-belt and round-hole castellated crane beam model,and uses the method of numerical simulation to study its high circumference.Fatigue performance.The results show that the fatigue performance of the castellated crane beam after the opening of the web is greatly reduced compared with the solid belly crane beam.Even if the opening size is small,the fatigue life is better than that of the solid belly crane.The beam is greatly reduced.By changing the parameters of opening number,opening ratio,web stiffener in the finite element model,the influence of different factors on the fatigue life of castellated crane beam is analyzed.The results show that with the increase of the number of openings,the fatigue performance of the castellated crane beam continues to decrease.With the increase of the opening ratio,the fatigue life of the castellated crane beam continues to decrease;the more concentrated the castellated hole distribution,the weakening of the crane beam The higher the fatigue resistance of the castellated crane beam is,the shorter the fatigue life is.The additional stiffening rib between the holes can effectively reduce the stress level of the dangerous section across the middle section,improve the fatigue life of the castellated crane beam,and enhance the structure.Anti-fatigue ability;the initial defect weakens the fatigue resistance of the castellated crane beam.The degree of influence is related to the existence position and size of the initial defect.The closer to the load position,the more obvious the weakening of the fatigue performance of the castellated crane beam.In summary,for the heavy-duty crane beam,the fatigue life is greatly reduced due to the increase of the section stress after the opening of the web,and the stress conditions have many influencing factors.Considering the safety factor,the castellated steel crane beam structure should not be used.