Wedged Cross Sections for Curved Steel Bridges

Curved bridges are often constrained by critical vertical clearance dimensions. The point of minimum vertical clearance is usually located at the inner girder of the bridge cross section, toward the curve radius point, and on the low side of the deck superelevation.

Traditional practice in bridge design would provide for all girders at a cross section to be of the same depth. Since curved bridges are superelevated downward toward the curve radius point, the inner girder sets the low elevation of the bridge cross section.

However, if the girders are made shallower toward the inside of the curve making a "wedge" shaped girder envelope cross section, those girder bottoms are raised up, and greatly improved vertical clearance may be obtained.

This approach was successfully used for a contractor's Value Engineering Cost Proposal to design and build two single span curved steel girder bridges, in lieu of the as-bid two-span and three-span concrete slab bridges, providing significant savings to the owner, MaineDOT, while minimizing approach roadway slope encroachments into sensitive wetlands.

The concept is further described with an example two-span continuous steel bridge, along with modeling information.

View content