The Research On Deflection Calculation Of Hexagon-hole Castellated Beams Considering Diameter-depth Ratio And Space-depth Ratio

As a new steel structural member, castellated beams are widely used in manycountries because of their rational section shape, light-weight, high load-carryingcapacity, beauty, economy and suitability, etc. Many foreign countries have setted therelevant specifications and standards to guide the design of castellated beams. But inChina, there are no written norms or standards at present, which to some extentlimiting the development of castellated beams. So far, the research on castellatedbeams is mostly focused on the welded castellated beams which are made bydislocation welding pore forming method, and the parameters considered areoutspread ratio and depth-span ratio, while few studies are made on the directly-madecastellated beams which are made by cutting holes. As for it is easy to make thedirectly-made castellated beams and no need to weld, the directly-made castellatedbeams will inevitably be popularized. So it is necessary to study the stresscharacteristics of the directly-made castellated beams. At present, there is no simpleand unified formula to calculate the deflection of castelled beams, which brings greatinconvenience to practical engineering calculation. Based on this idea, this thesisstudies the deflection calculation of regular hexagon-hole castellated beams made bycutting holes. The main research work includes:(1)Firstly, this thesis introduces the steps of making castellated beams bydislocation welding pore forming method and cutting holes method, the respective keyparameters of the two methods, and compares the advantages and disadvantages of thetwo methods;(2) By using Altfillisch’s vierendeed truss method, the deflection calculationformula is derived for simply supported castellated beams under uniformly distributedload and central concentrated load. Then the thesis points out its deficiencies, whoseapplicable scope is limited;(3) Based on the calculating principle of Altfillisch’s vierendeed truss method,and aimed at its disadvantages, improved Altfillisch’s vierendeed truss method is putforward, which considers the effect of diameter-depth ratio and space-depth ratio. Thenew method can be applied to the deflection calculation of directly-made castellatedbeams. Using the new method, a new formula is derived for regular hexagon-holecastellated beams under uniformly distributed load and central concentrated load; (4) On the basis of the theoretical formula deduced before, the thesis analyzesthe main factors influencing the castellated beams’ deflection, which arediameter-depth ratio, space-depth ratio and span-depth ratio. After a large amount ofcalculation, fitted simplified calculation formulas are proposed by considering thesefactors mentioned above. The simplified calculation formula can be used inengineering practice, which solves the problem that the theoretical formula is toocomplicated;(5) Using ANSYS to verify the simplified formula, it is found that the simplifiedformula’s precision is very high, and it can satisfy the engineering requirement, thenthe thesis points out the applicable scope of the simplified formulas.