An Overview of the Exodermic® Bridge Deck Design

An Exodermic® (or "composite, unfilled steel grid") bridge deck is comprised of a reinforced concrete slab on top of, and composite with, an unfilled steel grid. 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. The compressive strength of concrete and the tensile strength of steel are maximized.

Using standard components, the Exodermic® bridge deck system properties and span capacities are generated and can be obtained from the Deck Properties & Spans table. Through the use of larger main bars and/or thicker concrete slabs, longer span capabilities can be achieved. Decreasing cover over the rebar will reduce the bridge deck thickness if required for existing site conditions and reduce the weight of the bridge deck as well. Further weight savings are possible using a lightweight concrete mix.

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

Exodermic® bridge 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® bridge decks require no field welding other than that required for the placement (with an automatic tool) of the headed shear studs.

For more information about the Exodermic® bridge deck system you can contact the DS Brown Company at 419-257-3561