Steel pedestrian bridge with curved ramps

Students & Education
, , ,
1

Hello everyone,
I am a student at Coburg University of Applied Sciences and currently working on my study project: the design and calculation of a steel pedestrian bridge.
As you can see in the attached overview plan (image_2.png), the structure consists of a straight main span that transitions at both ends into complex, curved ramps (an S-curve on the left side and a spiral ramp/helix on the right side).
Since I want to model the entire structure completely in RFEM 6, I am facing some methodological questions and hope for your support or best practices:

  1. Modeling the curves and geometry: What is the best approach to accurately create the 3D geometry of the ramp-shaped, ascending curves and the helix in space? Is it advisable to import the centerlines directly from my DWG/DXF file (e.g., as a CAD background layer or direct import), or does RFEM 6 offer internal functions (such as formula-based node generation) that are more stable for this?
  2. Beam vs. surface elements: For the main girders and the bridge deck: Should I work purely with beams and eccentricities here, or is modeling the roadway slab as a curved surface (shell) more reasonable to correctly capture torsion?
  3. Coupling of components: Which joints or couplings are recommended for the transition between the rigid, straight bridge part and the more flexible, curved ramp structures?
    I have attached my current DWG plan as an image. I would greatly appreciate any tips, workflows, or references to similar Dlubal webinars/tutorials on bridge construction and complex geometries!
    Thank you very much in advance for your help.
    Best regards,
    Martial Edoung
    image
    image1787×802 575 KB
3

Hi Martial,

welcome to the community!

  1. I would use the existing DXF as a basis and starting point for modeling. Alternatively, RFEM also offers the possibility to work with blocks or parametrization using formulas. However, there is no special "bridge generator."

  2. This cannot be answered in general terms. Basically: as precise as possible, but only as precise as necessary. I consider modeling the superstructure as a shell and the substructure as bars to be sensible.

  3. Between bars, you use bar end hinges; between surfaces, line hinges. Alternatively, you can also model a gap and use rigid couplings in conjunction with a line hinge.

For orientation, you can also look at theses of other students:

Best regards
Stefan Hoffmann