LBS inside OpenBridge Designer, allows users to easily create models with longitudinal stiffeners within a girder element with a variable height. After the usual geometry and modeling steps for creating the main girders in the Member Definition tab, users can modify their heights by applying linear variables and then adding the longitudinal stiffeners. As shown in the screenshots below, at the Stiffeners Locations tab, by selecting the Longitudinal web Stiffener Type user can use a Relative or Absolute Location Type and then input the Vertical Location and the Vertical Reference as the Top or Bottom Flanges. 

      

The End Radius parameter for the Longitudinal Stiffeners Locations definition Tab above is used in the design as the R number: the End Radius, Return Radius, or Transition Radius. This is used inside the design routine for LBS for welded stiffeners in the fatigue category selection B, C, D, or E.

   

Stiffener Locations Dialogs (bentley.com)

Important to note, although, that the Stiffeners themselves are not yet designed in LBS.

communities.bentley.com/.../lbs-bearing-stiffeners-shear-stiffeners-and-connection-plates