Requirements for the fabrication of steel construction

When the curved rod is bent during the processing of the steel structure fabrication, the upper and lower flanges generate out-of-plane stress. For circular arcs, the value is inversely proportional to the radius of curvature. When the stiffener is not set, the beam web bears the tension or pressure generated by it, and after the stiffener is set, the stiffener and the beam web are jointly borne. In addition to the original stress of the flange, its out-of-plane stress should also be considered and calculated according to the three-sided support plate.

In addition, it should be noted that due to the greater stiffness of the flange near the web of the steel construction. Therefore, according to the elastic calculation, the out-of-plane stress distribution of the steel structure flange shows the law that the closer the distance to the web, the larger the value, and the distribution of the in-plane stress along the flange also has the same characteristics.

The welded beam composed of multi-layer welding is connected by the welding seam between the flange and the hand. During the welding process, the grid will generate large welding stress and welding deformation, and the force will be uneven. Especially in the changing section of the steel construction flange, the internal force line suddenly changes, and stress concentration occurs, which makes the beam in an unfavorable working state. Therefore, a layer of flange plate is recommended. When the load is large and the single-layer flange plate cannot meet the requirements of strength or weldability, the double-layer flange plate can be used.

When the outer flange plate is not set in full length, the value of the overhang length at the theoretical cut-off point is determined according to the test results at home and abroad. In the welded steel construction double flange plate girder, the measured stress in the flange plate is different from the theoretical calculation value within a certain length range from the end of the flange plate. The difference is the largest at the end, and gradually narrows inward, until the distance from the end, the two are basically the same. The size is related to factors such as whether there is an end weld, the ratio of the thickness of the weld to the thickness of the flange plate, etc.