EXODERMIC™ BRIDGE DECK DESIGN — AN OVERVIEW

An Exodermic™ (or “composite, unfilled steel grid”) deck is comprised of a reinforced concrete slab on top of, and composite with, an unfilled steel grid. This maximizes the use of the compressive strength of concrete and the tensile strength of steel. Horizontal shear transfer is developed through the partial embedment in the concrete of the top portion of the main bars which are punched with 3/4" holes.

Overall thickness of the system using standard components ranges from 6" to 9 1/2"; Total deck weights range from 39 to 74 pounds per square foot. Exodermic™ decks using standard components can span over 18'; larger main bearing bars and /or thicker concrete slabs can be chosen to span considerably further.

The concrete component of an Exodermic™ deck can be precast before the panels are placed on the bridge, or cast-in-place. Where the concrete is cast-in-place, the steel grid component acts as a form, the strength of which permits elimination of the bottom half of a standard reinforced concrete slab.

Exodermic™ decks are made composite with the steel superstructure by welding headed studs to stringers, floor beams, and main girders as appropriate, and embedding these headed studs in full depth concrete. This area is poured at the same time as the reinforced concrete deck when the deck is cast-in-place, or separately when the deck is precast. Exodermic™ decks require no field welding other than that required for the placement (with an automatic tool) of the headed shear studs.