Evaluation of Short Span Steel Bridge Design Standards

The Federal Highway Administration’s National Bridge Inventory consists of over 600,000 bridges. Of these bridges, over 25% are considered either structurally deficient or functionally obsolete.

While several state bridge departments have standard designs for bridge components in order to speed up the design process in replacing these bridges, few have standard designs for the bridge superstructure.

Standard short-span steel bridge designs were developed to create a design aid for bridge engineers. In this package, designs with spans ranging from 40 feet to 140 feet in 5 foot increments were developed for rolled wide flange beams, homogeneous steel plate girder sections and hybrid steel plate girder sections.

The rolled sections were designed using two design approaches: the lightest weight possible and the lightest weight possible with a limited section depth. This limited suite provides the opportunity for stock piling common rolled beam sections and common steel plate sizes. In utilizing this design aid, a more efficient transition from design to construction can be achieved.

Contained in this report is a design evaluation of two sample bridges. Both of these bridges were 80-foot simple span bridges with cross-sections capable of carrying two traffic lanes.

One of the bridges evaluated utilized homogeneous plate girders for the steel superstructure whereas the other utilized rolled beams. Girders for these bridges were selected from the standard designs and evaluated according to current AASHTO LRFD Specifications.

Both design options are shown to perform adequately under AASHTO Specifications.

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Authors:

• Karl E. Barth, Ph.D.
• Amy S. Barth, Ph.D.
• Gregory K. Michaelson, Ph.D.
• Cory L. Gibbs, E.I.T.
• Robert M. Tennant