Preassembled Steel Space Frame Bridge

Traditional bridge construction practice often leads to excessive site construction time, relatively poor and unsafe working conditions, and high labor costs. Industralized preassembly procedures can reduce these problems by concentrating most of the construction effort in the factory rather than the field. However, accomplishments with quick-assembly steel bridges have been limited and relatively little preassembled steel segmental bridge construction has been attempted. Incentive does come from the building industry, where recent success with three-dimensional steel truss construction has caused steel to become more competitive with other structural materials for covering large areas. Space frames have also been successfully used for long span support structures for highway signs, and the United States Marine Corps is currently developing an aluminum alloy sectionalized bridge to carry a range of loads over varying spans. Numerous precast segmental prestressed concrete structures are evidence of the feasibility of off-site construction, including transporting and erecting large sub-assemblies. Since steel offers the advantage of reduced weight and ease of handling, and because developments in numerically controlled steel fabrication methods have reduced shop labor, a comparative study of a preassembled steel space frame bridge and three conventional highway grade separation bridges was conducted.