The National Steel Bridge Alliance (NSBA) has released an updated version of its Skewed and Curved Steel I-Girder Bridge Fit document at www.steelbridges.org/bridgefit. This free resource offers additional guidance on proper detailing of bridges to ensure constructability.
Fit or fit condition refers to the deflected girder shape under specific loading conditions. This is important to steel bridge fabricators because it determines how the cross-frames and diaphragms are detailed to fit to the girders. In addition, fit affects bridge constructability by determining how much force is necessary to align the girders and cross-frame elevations.
The new document offers additional and expanded insights into how bridges should be detailed. Updates include minor changes to recommended fit conditions for horizontally curved bridges based upon the recently finalized Guidelines for Reliable Fit-Up of Steel I-Girder Bridges. To complement the Fit document, NSBA has also released a larger guide document that delves into the theory behind the numbers, available here.