Heat curving is a process in which a straight girder is heated to induce horizontal curvature.  This is a well-established method, and it does not adversely affect the material properties of the girder.  Providing this option can make a steel bridge more economical to fabricate. However, not permitting the use of heat curving should not eliminate the use of horizontally curved girders entirely, as the girders can be fabricated using cut-curving techniques for the flanges instead.

The AASHTO LRFD Bridge Design Specifications allow the use of heat curving, with restrictions. For horizontally curved steel rolled beam and constant depth welded I-section plate girders, the AASHTO LRFD Bridge Design Specification Article 6.7.7.2 requires that Engineers indicate on the contract documents whether heat curving is permitted in accordance with the Article 11.4.12.2.2 of the AASHTO LRFD Bridge Construction Specification.  However, evaluation and interpretation of this article can be challenging for even the most seasoned engineers.  This spreadsheet is intended to help simplify that task.  For more information, please refer to the NSBA Heat Curve Calculator users guide.

For more information on heat curving, consider downloading the FHWA "Manual for Heat Straightening, Heat Curving and Cold Bending of Bridge Components."  This manual provides background knowledge and information to use heat straightening, heat curving and cold bending for the fabrication or repair of steel bridge components.

The current version of the NSBA Heat Curve Calculator (v1.00) was released in July 2023.  Click here to view a complete listing of updates and fixes.