Weathering steel bridges should be detailed to ensure that all parts of the steelwork can dry out, by avoiding moisture and debris retention, and ensuring adequate ventilation.
• Grind flush weld details which may cause water traps.
• Provide 50mm copes where stiffeners are attached to the bottom flange.
• Avoid closely spaced girders to aid ventilation.
• Avoid overlaps, pockets and crevices, which can attract moisture by capillary action.
• Hermetically seal box girders, or provide adequate access, drainage, and ventilation.
• Ensure that web plates of box girders extend 20mm below the bottom flange.
For steel composite decks, consideration should be given to providing wide deck cantilevers, with well formed drip details to shelter the girders from wind blown rain. In addition, any outlet pipes from the deck above the girders should be non-metallic and of sufficient length that the salt-laden water does not spray onto steelwork surfaces. Run-off from the steelwork during the initial years, as the ‘patina’ develops, will contain corrosion products which can stain substructures. This potential problem can be avoided by providing drip details on the bottom flanges of girders and ensuring bearing shelves have generous falls to internal substructure drainage systems. Compatibility with other materials Although rust staining should not occur on a well detailed weathering steel bridge, it is worth noting that concrete, stone and unglazed brick are difficult to clean. Hence, it is recommended that substructures are sealed with washable organic coatings to facilitate cleaning with commercial products, should rust staining occur. Other issues to consider include:
• Elements buried in soil should be painted.
• Interfaces between steel and concrete should be sealed with an appropriate sealant.
• Elements encased in concrete need not be painted.
• Connections to galvanically dissimilar materials such as zinc or cadmium plated bolts, should be avoided. As with other forms of construction, the removal of graffiti from weathering steel bridges is difficult, so measures to discourage public access to the girders should be considered. However, this should be balanced with the need to provide access for inspection, monitoring and cleaning.
Drainage of weathering steel
Carbon Steel, Corten Steel, Stainless steel
Rust, Bare, Powder Coated, Polished, Black Heat-resisting Paint, Iron Oxide
Diameter : 320mm--1200mm
Thickness : 1.2mm--3.0mm
Inside : Anti-wear foam paper
Outside : Plywood box
Free (without any condition)
OEM & ODM
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