Stiffening and Sizing of a Steel Box Girder for a Railway Bridge Using Sofisti

I am currently working on the design of a railway bridge (see sketches).
(Simple span bridge: L = 45m, B = 15m)

I have two questions:

1.) Can I use Sofistik to optimize the dimensions of the girders, as in the design of a plate girder bridge, so that Sofistik suggests the optimal dimensions? The current girders are just an assumption.

2.) Since my construction height is very limited, I am unsure whether the plate girder bridge will work at all (otherwise, the bridge would extend into the 100-year flood level). Therefore, I would like to analyze a steel box girder, which may require lateral cantilevers due to the wide bridge deck (pedestrian and edge walkway on both sides). How should I model the stiffeners inside and outside the steel box girder, what aspects should I consider, and can I initially assume dimensions and let Sofistik adjust them accordingly?


SOFISTIK3

Hi Joh,

regarding Q1:
No, SOFiSTiK does not optimise cross-sections at the touch of a button.
If a cross-section only consists of a standardised steel profile, you can use in PROG AQB command STRE D or STRE DG to obtain cross-section suggestions (see AQB manual).

Regarding Q2:
It is not clear from your description which stiffeners you mean, so just a general answer:
Stiffeners that are arranged in the longitudinal direction of a beam, e.g. at intervals of 3.00 m (e.g. stiffeners in the area and in the plane of cross-member connections), cannot be defined within a cross-section.
Also lateral cantilevers due to the wide bridge deck cannot be defined in a cross section. These must defined as real lateral beams in a 3D-system with necessary distance.
Here too, SOFiSTiK does not make any cross-sectional adjustments, the user must estimate the dimensions and adjust them manually. SOFiSTiK can only determine the required reinforcement, the user must specify the dimensions of cross-sections or the position of the reinforcement.

I hope this helps.
Best regards,
Jost