Concrete Girder Bridge

What It Means

Concrete girder bridges use reinforced or prestressed concrete beams as the primary superstructure, in contrast to steel girder or slab superstructures. Prestressed concrete girders dominate modern short-to-medium span bridge construction in the U.S., with standard AASHTO girder sections (AASHTO Type I through VI, bulb-tees, and Florida U-girders) used for spans from 40 to 180 feet. Adjacent prestressed box beams are common on rural county bridges for spans of 30-100 feet. Cast-in-place reinforced concrete T-beams and multi-stem girders were widely used from the 1920s through the 1960s and remain a significant portion of the NBI, particularly on older state highway and county road bridges. Concrete girders offer lower lifecycle cost than steel in many applications due to reduced maintenance (no painting, though they can still suffer from deck and bearing issues), higher fire resistance, and natural corrosion protection of reinforcing steel when adequate concrete cover is maintained. The trade-offs include higher dead load (requiring heavier substructures), susceptibility to chloride-induced rebar corrosion in northern climates, limited span capability without post-tensioning, and prestressing strand corrosion risk in older adjacent box beam bridges. Approximately 40% of the U.S. bridge inventory uses some form of concrete girder construction. Modern designs increasingly use high-performance concrete (HPC) with compressive strengths of 8,000-10,000 psi, lower permeability mixes to resist chloride penetration, and epoxy-coated or stainless-clad rebar in harsh environments. FHWA's 2005 guidance on adjacent prestressed box beam inspection, issued after the Lake View Drive Bridge collapse in Pennsylvania, requires enhanced inspection of transverse connections and prestressing strand condition on these structures.

Frequently Asked Questions