Deck Types Defined
There are two basic types of steel grid bridge decks
Grid reinforced concrete bridge deck
Open steel grid deck
Grid reinforced concrete bridge deck can be further broken down into:
A thin reinforced concrete slab on top of and composite with an open grid. Concrete is above the grid cross bars.
A grid where the top half is filled with concrete. May be flush filled or have a minimum 1-1/2" monolithic concrete overfill (2" recommended).
A grid that is fully filled with concrete. May be flush filled or have a minimum 1-1/2" monolithic concrete overfill (2" recommended).
Exodermic and half-filled decks are generally 30-50% lighter than conventional reinforced concrete slabs, making them a superior lightweight deck option when looking at economical ways to reduce the dead load on a structure. On rehabilitation projects, this dead load reduction can result in increased live load capacity with little or no structural strengthening. These lightweight deck systems have also been used on new and rehabilitated movable bridges when a solid driving surface is desired. Both Exodermic decks and concrete filled grids are excellent bridge deck choices for accelerating construction using either precast or cast-in-place (CIP) panel installation.
Open grid bridge decks can be further broken down to
Rectangular style open grid
A grid consisting of main bar, cross bars and supplemental bar arranged in a rectangular grid pattern
Diagonal style open grid
A grid consisting of main bar, cross bars and supplemental bar arranged in a rectangular grid pattern with the addition of a diagonal bar that forms a star like pattern
Open grids are one of the lightest bridge deck systems available and are often found on movable bridges and steel truss structures. Since open grids provide a superior lightweight advantage, they are a suitable options for deck replacement in-kind on structures that cannot handle additional weight. Diagonal grids generally provide better ride quality, skid resistance and fatigue performance versus rectangular grids