Wide flange shapes are used as a common superstructure element for bridges between approximately 20 and 90 feet. These elements are aligned parallel to traffic flow under the bridge deck to support the loads of the bridge. Generally the deck is attached to the girders in such a way to make the deck and girders behave cooperatively as composite members. While in longer spans the unit weight of steel used for the bridge can be higher than that of steel plate girders, the unit cost of steel is much lower for rolled members. Transverse stiffeners are not normally required for rolled sections and simple diaphragm details aid in making rolled sections an affordable superstructure.
The Short Span Steel Bridge Alliance brochure implies that this alternative can be applied to spans between approximately 20 and 90 feet. The superstructure supports the deck and applied live loads and provides clearance for traverse beneath the bridge.
Generally, for span lengths less than 200 feet (all bridges considered in this report), girders can be erected with little to no falsework. During erection, pier brackets are often used to provide stability to negative moment sections of the bridge until the positive moment sections are erected.