Characteristics and composition of steel  box  girder 

Introduction:
Steel box girder, is a common structural form of long span bridges. It is generally used on bridges with large spans. It is called a steel box girder because its appearance is like a box.

Features:
In the long-span cable-supported bridge, the main beam of the steel box spans several hundred meters and up to several kilometers. It is generally divided into several beam sections for manufacturing and installation. Its cross section has wide and flat shape characteristics, and the aspect ratio reaches 1 : 10 or so.

composition:
Steel box girder is generally composed of a top plate, a bottom plate, a web, and a transverse partition, a longitudinal partition and a plus
The ribs and the like are connected by means of all welding. The top plate is an orthotropic bridge panel composed of a cover plate and a longitudinal stiffener.
The thickness of each typical steel box girder can be: cover plate thickness 14mm, longitudinal U-shaped rib thickness 6mm, upper mouth width 320mm, lower mouth width 170mm, height 260mm, pitch 620mm; bottom plate thickness 10mm, longitudinal U-shaped stiffener The inclined web is 14mm thick, the middle web is 9mm thick, the transverse partition is 4.0m, the thicess is 12mm, and the beam height is 2~3.5m.
Steel box beam is a commonly used structural form in engineering. In order to study the influence of the spacing of the diaphragm on the distortion of simply supported steel box girder under concentrated load, the simple supported steel box girder with different number of transverse partitions is set to compare the concentration. Distortion effect and rigid torsion effect under load, the maximum distortion effect is obtained with the number of diaphragms. Concentrated load is applied to the top of the box girder, and it is used according to four conditions: distortion, rigid torsion, symmetrical bending and eccentric load. The method of load decomposition is calculated.