Settlement loads, springs and foundation

SOFiSTiK Teddy
1

Good morning,

I have a question regarding settlement load application. A window picture of the model is posted below.

The superstructure is modeled together with piers, a foundation plate, and a deep pile foundation. The bridge superstructure beam nodes are coupled with springs, which connect this assembly directly to the piers. Therefore, the springs serve as the load-bearing elements. The pier is coupled with the foundation plate, which in turn is connected to the piles supported by springs (for defining base resistance).

In a situation where the superstructure is modeled with the foundation, what is the best way to account for settlement loads in different axes? In conventional models with separate superstructures and normal load-bearing elements, it is possible to directly apply node deformations (e.g., KNOT TYP WZZ 20). However, in this specific case, I cannot find a good alternative for that.

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Thanks in advance.

Grüße,
Lucas

2

Hello Lucas,

I think it could be a solution to model a beam element (with some fictive cross section, like 1 x 1 m) between superstrucutre and pier and apply a strain load “EX” for the beam. The value for the strain should be chosen in a way that it causes an axial deformation (absolute value) equally to your value for the settlement.

Best regards,
Adrian

1 Like
3

Hello Lucas,
apart from the above described solution with dummy beams you may try to use the following approach. Unfortunately there is no possiblity in module SOFILOAD to apply a spring loading, like FEDE … However in the ASE module you can experiment with applying a prestress on the particular spring element as follows:

+prog ase
head
lc 999 type none
elem etyp spri no 1234 facs 1e-4 prex -10000 $ equivalent to 10 mm displacement when the spring constant is 1e6 kN/m
end

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