National Steel Bridge Alliance

Design Resources

NSBA provides a number of resources to help engineers during the preliminary design phase. These resources work from various levels of refinement toward the goal of generating economical steel solutions. Most coarse are the Steel Span to Weight Curves which provide steel weights, in pounds per square foot of bridge deck, for various span arrangements. The next level of refinement is the Continuous Span Standards. The Standards include pertinent steel information, such as plate sizes, steel weights, and camber diagrams, for three-span bridges. Finally, NSBA's LRFD Simon design and analysis software, is the most refined resource and is a powerful tool for generating preliminary designs that meet project constraints.

Steel Span to Weight Curves

The Steel Span to Weight Curves are the quickest way to determine the weight of steel per square foot of bridge deck for straight, low skew, plate girder bridges. They are also a great way to compare various span arrangements and girder spacings.  With very little effort the weight per square foot can easily be converted to a potential dollar value for the steel superstructure.





Continuous Span Standards

The Continuous Span Standards represent an excellent starting point for 3-span continuous steel plate girder design. They serve to help reduce the time required for preliminary bridge superstructure layout, girder plate sizing, and more.



NSBA Guide to Navigating Routine Steel Bridge Design

This guide is intended to complement the 9th Edition AASHTO LRFD Bridge Design Specification and addresses the design of steel superstructures for "routine steel l-girder bridges." It illustrates which provisions of the AASHTO Specification are applicable to the design of these types of structures, and perhaps more importantly, which provisions are not applicable or are only partially or conditionally applicable.

If a given bridge somehow falls partially outside the limits of the definitions of a "routine steel l-girder bridge" or outside the exclusions of this scope, this guide may still provide value to designers. The purpose of this guide is to help engineers streamline the design process, avoid unnecessary or misguided effort, and simplify their approach to the necessary tasks associated with the design of a more routine steel l-girder bridge. Read more about this guide in the February issue of Modern Steel Construction: Streamlined Design



LRFD Simon

Simon is a line-girder analysis software that can be used to analyze straight and low skew plate girder and tub girder bridges.  Simon is perfect for those bridge projects that don't require a 3D finite model and where hand calculations would be too involved.



NSBA Splice

NSBA Splice takes the time consuming task of designing and checking a bolted splice connection and rewrites the process as a simple input and output form.  NSBA Splice allows the designer to quickly analyze various bolted splice connections to determine the most efficient bolt quantity and configuration.



IRM Evaluator

The IRM Evaluator automates much of the process for evaluation of built-up members for internal redundancy. The IRM Evaluator follows provisions of the new AASHTO Guide Specifications for Internal Redundancy of Mechanically-Fastened Built-up Steel Members evaluating internal redundancy and establishing a special inspection interval.


For questions regarding Design Resources, please send an email to