What is a Bailey panel

There are two types of Bailey panels: Type 321 and Type 200. The theoretical weight of Type 321 is 270 kg, and Type 200 is 292 kg. It was invented in 1938 by British engineer Donald West Bailey. This type of bridge is made of high-strength steel, composed of lightweight standardized truss unit components, as well as crossbeams, longitudinal beams, bridge decks, bridge seats, and connectors. Using specialized installation equipment, it can be quickly assembled on-site into truss beam bridges suitable for various spans and loads. During World War II, it was widely used for bridge repairs or temporary bridge construction on the Eurasian battlefields. After the war, the Bailey bridge was improved and converted for civilian use. The improved version in the United States is called the Acrow bridge. China's highway department designed and named a prefabricated highway steel bridge using 16Mn steel. One set of equipment can build single-lane bridges with spans of 9 meters, 12 meters, 15.60 meters, and 63 meters, capable of bearing loads of vehicle class 10, vehicle class 15, vehicle class 20, strip class 50, and trailer class 80. These bridge components are also widely used as construction scaffolding or towers.

Composition of Bailey panel

The Bailey panel consists of upper chords, lower chords, main rods, and diagonal rods. Both ends of the upper and lower chords have male and female tenons, with pin holes for frame connections. The chords of the Bailey panel are made of two No. 10 channel steels placed back-to-back. The lower chord is welded with multiple steel plates with round holes. Both upper and lower chords have bolt holes for connection with steel bars and double-layer trusses. The upper chord also has four bolt holes for connecting supports. Two of these holes are used to connect double or multiple rows of trusses in the same section. The two holes at both ends are for cross-year connections. When multiple rows of shell plates are used as beams or columns, supports must be used to connect the upper and lower parts of the shell plates. On the lower chord, there are four transverse beam pads with tenons to determine the position of the crossbeam in the plane. On the steel web plate at the end of the lower chord, there are two elliptical holes for connecting wind-resistant tie rods. The vertical rods of the Bailey panel use No. 8 I-beams, and one side of the rod's lower chord has square holes for
The crossbeam fixing device is used to assemble the crossbeam. The material of the Bailey panel is 16Mn, with each panel weighing 270 kg. The "321" national bridge is a type of prefabricated highway steel bridge characterized by a lightweight structure, easy assembly and disassembly, strong adaptability, and can be quickly built using simple tools and manpower. It is suitable for five load types: vehicle class 10, vehicle class 15, vehicle class 20, truck class 50, and trailer class 80. The clear width of the bridge deck is 3.7 meters, and it can form simply supported beam bridges with spans ranging from 9 meters to 63 meters, and can also be used to build continuous beam bridges.

Bailey panel specifications

The standard specification of the Bailey panel is 3"1.5 meters, and non-standard Bailey panels can also be customized. Currently, there are two specifications of Bailey beams: imported and domestic. The truss nodes of domestic Bailey beams use 16Mn steel, the pins use manganese-titanium steel, the pins use spring steel, the coal rods use T505X, and the bridge deck and wheel stops use pine or fir wood. The allowable stress of the materials should be increased by 30% based on the basic stress. When a single steel component exceeds the above regulations, it must not exceed 85% of its yield point. The allowable stresses used in the design are as follows: bending stress, compression, and compression along the wood grain direction are 16.2 MPa; shear stress along the wood grain direction during bending is 2.7 MPa. Elastic modulus E = 98.5 x 10.5 MPa. Steel—16Mn steel's tensile stress, compression, and bending stress are 1.3 x 210 = 273 MPa; shear stress is 1.3 x 160 = 208 MPa. Complex manganese-titanium's tensile stress, compression, and bending stress are 0.85 x 1300 = 1105 MPa; shear stress is 0.45 x 1300 = 585 MPa. Most existing imported Bailey beams are products from the 1940s, with a material point strength of 351 MPa and allowable stress of 0.7 x 351 = 245 MPa. The allowable stress of the pins can be considered the same as that of domestic pins.