Customized Steel Plate Girder Bridges Single Cell Box Footbridge Pedestrian Overpasses

When it comes to bridges, the steel girder bridges are one of the most common types of bridges. They are strong and durable as they are made up of steel which is a very strong material.

Girder is a term used in construction to refer to a supporting, horizontal beam that can be made from a variety of construction materials such as steel, concrete, or a combination of these materials. A girder bridge is a basic, common type of bridge where the bridge deck is built on top of such supporting beams, that have in turn been placed on piers and abutments that support the span of the bridge. The types of beams used for girder bridges are usually either I-beam girders, so called because their shape is reminiscent of a capital Roman letter I, or box girder beams that are made of steel or concrete and shaped like an open box. Girder bridges are most commonly used for straight bridges that are 33-650 feet (10-200 m) long, such as light rail bridges, pedestrian overpasses, or highway fly-overs.

Footbridges are needed where a separate pathway has to be provided for people to cross traffic flows or some physical obstacle, such as a river. The loads they carry are, in relation to highway or railway bridges, quite modest, and in most circumstances a fairly light structure is required. They are, however, frequently required to give a long clear span, and stiffness then becomes an important consideration. The bridges are often very clearly on view to the public and therefore the appearance merits careful attention.

Steel offers economic and attractive forms of construction which suit all the requirements demanded of a footbridge. Steel box girders are very commonly used for footbridges over 30m span. Box girder footbridges use an all-steel configuration as the entire cross section including the parapets can be fabricated. The top flange of steel box girder acts as the floor of the bridge, and there are usually short cantilevers either side of the box. This form has the benefits of good torsional stiffness, which can simplify support arrangements and clean surfaces which minimize maintenance.

Advantages of box girders as Footbridges

• Reduce the requirement for support points
• Have high strength and torsional stiffness that give greater and better suitability for horizontally curved bridges
• Ensure enhanced durability
• Require minimum maintenance of simple protective coatings as these have less exposed surface and only a few edges