For stability designs according to the General Method of Eurocode 3, it is necessary to define boundary conditions in order to determine the critical load for the stability failure.
In the example of the truss bridge, the transverse beams should be designed according to this method. To do this, create a new boundary condition in the Navigator via "Types for Steel Design" - "Boundary Conditions". A separate eigenvalue solver is available internally for the general method, for which you can define the boundary conditions in the "Nodal Support" tab.
In this case, it is appropriate to assume the lateral and torsional restraints at the start and end nodes, and you can assign the boundary condition to the crossings.
