Steel beam

H-shapedfor bridge construction

Description Steel plate girders are one of the most common steel superstructure elements. When used in a bridge structure, the plate girders are installed parallel with the direction of traffic. Floorbeams are placed transversely under the deck to distribute the bridge loads. Similar to rolled steel wide flange members, the deck is placed causing the deck and girders to act as composite members. The shape of steel plate girders differ from rolled sections in that rolled sections are doubly-symmetric "I-shaped" sections and steel plate girders can be detailed to be more efficient and are generally only singularly-symettric. These customizing options cause steel plate girders to have a lighter unit weight. The more difficult diaphragm details and the need for transverse stiffeners lead to this choice not always being as cost-efficient as rolled sections for a wide range of short span situations. Application The Short Span Steel Bridge Alliance brochure implies that this alternative can only be applied to spans between approximately 60 and 140 feet. The superstructure supports the deck and applied live loads and provides clearance for traverse beneath the bridge.