Equivalent Stiffness of Cross Frames

[BecksterFEA]

Has anyone looked at the equivalent stiffness of cross frames when modeling a single girder line? Need to do a buckling analysis to look at a super deep web plate at a rigid frame pier and system LTB is controlling given that I have not provided any lateral brace points. Full lateral fixity is not likely at these locations. I looked at the CALTRANS method but this seems to be providing lateral stiffness at end cross frames only as part of a bent system. Though the equation seems to be derived directly from the stiffness matrix of a 2D bar element. Thanks!