Precast, prestressed concrete I-girders are more economical than other bridge systems, if the span length allows them to be used in full span segments, i.e., for spans up to about 150ft (46 m). Many designers are unfamiliar with the possibility of splicing I-girder segments to reach longer spans in the range of 150 to 280ft (46 to 85 m) and therefore rule out this potentially economical alternative. The following paper provides a summary of a state-of-the-art report on the design and construction of spliced I-girder bridges, which are quickly gaining popularity in the United States and Canada. The report was prepared by the University of Nebraska on behalf of the Bridges and Bridge Producers Committees of the PCI. The full report is available as a separate PCI document. The report contains information on over 40 bridge projects and gives design, production and erection considerations, and other details for many of these bridges. It also includes a fully worked example of preliminary design of a 350ft (106m) long overpass, made of two equal spans. The example calculations are done by a handheld calculator without need for any specialized computer facility. Also included is reference to a PC-based computer software for detailed time-dependent analysis of this bridge type.
