Study on Mechanical Properties of Web for Steel Octagon-Web Beam

At present, most of the bridge projects in China are still simply supported beam bridges. Under the action of transverse load, the simply supported beam bridge is mainly flexural. As a kind of steel structure girder used earlier, honeycomb beam has the characteristics of strong bending resistance, but it is rarely used in simply supported beam bridge. This is mainly due to the large web height of honeycomb beam, which is prone to web buckling distortion under dynamic loads such as vehicle loads. In order to apply the honeycomb beam to the field of bridge engineering, based on the appearance of honeycomb beam, a new type of steel structure main beam-steel octagon-web beam was proposed. The web stress calculation method and pure shear buckling calculation coefficient of the structure were studied in order to provide reference for the practical application of the structure.Based on the assumption of the Vierendeel truss theory, the web of the structure is divided into five calculation areas, the web stress calculation method is proposed and the corresponding calculation formula is obtained, and the rationality of the web stress calculation method is verified by comparing with the test results. In order to study the pure shear buckling coefficient of the web, based on the pure shear rectangular thin plate buckling calculation theory, the general finite element software ABAQUS is used to calculate the buckling coefficient for 480 octagonal thin plate with different design parameters and different boundary conditions. By modifying the calculation formula of the pure shear rectangular thin plate buckling coefficient with different boundary conditions, the buckling coefficient of the regular octagonal perforated web under the pure shear stress is obtained. The results show that under the transverse load, the bottom slab and top slab of the structure are mainly subject to axial force, and the shear force effect can be ignored, while the web is mainly subject to shear force, and the axial force effect can be ignored. Through the static load bending test of the specimen, the bending failure mode of the structure is obtained, and the web buckling phenomenon occurs at the loading point of the test piece. The measured values of the strain at the edge of the web opening are converted into the actual values of the stress, and compared with the calculated values of the web stress. It can be found that the proposed web stress calculation method can better predict the distribution mode of circumferential stress of circular holes, and the circumferential stress distribution is approximately uniform. In the calculating section θ=π/2, there is a large difference between the theoretical calculation and the measured values due to the calculation error caused by the assumption that the center of the circular hole is the inflection point in the simplified calculation. Based on the finite element software ABAQUS and data fitting, the buckling coefficient of octagonal circular perforated plate is proposed, which can provide a reference for the relevant design of the structure.