Steel provides great flexibility in the design of girder flanges, webs, stiffeners, field splices, and cross-frames. However, designers routinely face repetitive design decisions regarding material thickness and sizes for the routine steel I-girder bridges. In fact, two designers could design a steel I-girder bridge for the exact same span lengths and bridge width and implement girders that have different flange and web sizes, as well as differing cross-frame layouts and member designs.

These repetitive decisions and varieties in designs are now in the past with these new AISC/NSBA Standard Plans for Steel Bridges, which simplify and infinitely speed up the bridge design process.

Developed as part of the Need for Speed initiative, the AISC/NSBA Standard Plans for Steel Bridges provide dozens of straight steel I-girder bridge plans for a suite of various span arrangements and lengths--optimized for cost-efficiency throughout design, material selection, fabrication, and construction. All of the designs satisfy the provisions of the newly released AASHTO LRFD Bridge Design Specifications, 10th edition.

The designs cover one-, two-, three-, and four-span configurations with span lengths ranging from 80 feet to 300 feet, and girder spacings of 8, 10, 12, and 14 ft.

These Standard Plans for Steel Bridges:

• speed up the design process of I-girder bridges;
• make the fabrication process more efficient and cost-effective;
• optimize and standardize web, flange, stiffener, and field splice plate sizes that can be readily obtained by fabricators from typical mill plate widths and thicknesses;
• provide cost-efficient diaphragm and cross-frame standards for the entire suite of identified bridges.

The Standard Plans for Steel Bridges represent the most efficient bridge designs industry-wide for use in the U.S., from mill ordering to fabrication to erection--as opposed to merely the lightest. All of the bridge designs consider constructability as part of the design, including the wind on the steel framing, deck placement sequences, and the loading effects from deck overhang brackets. These standard plans also provide cost-efficient diaphragm and cross-frame standards for the entire suite of identified bridges.

Of course, designers can still perform their own analyses to verify the suitability of the elements provided in these standards for their particular bridge. However, NSBA strongly encourages designers to use the flange and web plate sizes, field splice plates, cross-frame members, etc., in these standards to take advantage of what fabricators can readily obtain.

Does your bridge not precisely fit these Standards? That is okay. You can use the standard plans that best represent your bridge, putting you nearly at the finish line for your design.

Future examples will further demonstrate how these Standard Plans for Steel Bridges should be used when a designer’s span length and/or girder spacing does not fit exactly within the suite of identified span arrangements and girder spacings. Furthermore, the LRFD SIMON files for each of these bridges in these Standard Plans for Steel Bridges will be provided as well so that designers can readily make input changes as needed for their specific project.

Single Span Bridges and Multi-span Bridges with Link Slabs Standard plans for single span bridges ranging from 80 ft to 300 ft span lengths. This document includes details for girders, cross-frames or diaphragms, lateral bracing, bolted field splices, girder reactions, and the concrete deck. It also includes Link Slab details for those who need multi-span bridges while eliminating interior deck joints.                    View More

Two-Span Continuous Span Bridges Standard plans for two-span continuous bridges with equal spans ranging from 100 ft to 250 ft.    This document includes details for girders, cross-frames or diaphragms, lateral bracing, bolted field splices, girder reactions, concrete deck, and the concrete deck placement sequence.                     View More

Three-Span Continuous Span Bridges Standard plans for three-span continuous bridges with spans ranging from 150 ft to 300 ft. End span lengths are optimized for the center span length. This document includes details for girders, cross-frames or diaphragms, bolted field splices, girder reactions, concrete deck, and the concrete deck placement sequence.       View More

Four-Span Continuous Span Bridges Standard plans for four-span continuous bridges with spans ranging from 150 ft to 300 ft. End span lengths are optimized for the two middle span lengths. This document includes details for girders, cross-frames or diaphragms, bolted field splices, girder reactions, concrete deck, and the concrete deck placement sequence.       View More

Acknowledgement: These AISC/NSBA Standard Plans for Steel Bridges were developed under a contract with Russo Structural Services, who was supported by Genesis Structures, Inc, and M.A. Grubb and Associates, LLC. Their efforts and contributions to development of the  AISC/NSBA Standard Plans for Steel Bridges are gratefully appreciated.