Research Of The Calculation Of The Deflection Of Octagonal Hole Castellated Beam

As a new steel menber, castelled beam is often used in long-span structures because it has many advantages, such as the rational section form, light-weight, high load-carrying capacity, and so on. But at present, there is no technical standard or specification on it to guide applications and design in our country. This severely restricts the castelled beam’s widely use in China. At present, there is no conveniend or uniform calculation method to the deflection of castelled beam. Therefore, it is necessary to do more researches on the existent problems. The main research work on the deflection of octagonal hole castelled beam covers the following aspects:(1) According to the domestic and overseas references, this article summarizes the method of making circular hole(elliptical hole), hexagonal hole, octagonal hole and the corresponding tapered castellated beam.(2) Based on the classical theory of mechanics of materials, this article describes the theoretical derivation of the Altfillisch, which is assumed the castellated beam as a vierendeed truss, and discusses the values of the parameters of its expression. Equivalent stiffness method is proposed and its calculation expression is derived in this article. Using amounts of the finite element analysis fits out the equivalent bending stiffness and the equivalent shear stiffness’s expressions, and verifies their accuracy.(3) According to the domestic and overseas references and the expressions which are derived in this article, this article summarized the different methods of caculating the deflection of castellted beam, and discusses the difference and connection of the common methods-the FEA, the Altfillisch and the equivalent stiffness method.(4) Based on the FEA, this article evaluates the precision of the oretical formula of the deflection of castellted beam on the different parameters and under different load. And found that the accuracy of simplified theoretical formula is very high and the caculation value is slightly larger than the true value, so the formula used in the project is biased safe.(5) This article discusses the impact of eight factors on the deflection of castellted beam. And also calculate and correct the value of the magnification factorηat different expansion ratio, different high-span ratio and under different load. This article discusses the changes of the deflection of several the commonly used standard castellted beam which is under different load and parameters. And this can provide reference and proposal for selecting different types of castellted beam in engineering practice. Finally, this article presents a simplified formula which can be used in engineering practice for the deflection of castellted beam.