# Tangential bearing of a bridge

Hello,

I have a bridge model where I have difficulties with bearing. The bridge has 5 fields. The two middle pillars are fixed pillars (translation in x,y and z locked). The two outer pillars allow a movement of the superstructure in the x-direction. At the abutments the bridge is also movable in the x-direction.

Between the superstructure and the pillar are rigid coupling rods. Between the coupling rods and the pillars are springs with a zero length. Same principal at the abutuments with shorter rigid rods.

Problem 1:

• The springs cannot be rotated in such a way that only a displacement in the x-direction of the bridge axis is allowed (“z-orientate” in the component “index to beam” and “orientate element” did not work or I probably applied it incorrectly)

In the GH file, the springs are currently incorrectly rotated (Top View):

How it should be:

Problem 2:

• The torsional bending moment is not correct at the moment (Load Case 0). It actually had to look like this:

Current appearence:

Here I have already tried a lot of spring adjustment, but I could not find a solution.

Does anyone know how to adjust the springs correctly or whether you generally have to model them differently? I would be very happy to receive support

Tangential bearing.gh (85.6 KB)

Hello

problem 2 depends on problem 1

it’s hard to get into your definition, but I understand that your C1 to C4 columns are well oriented

maybe you can disassemble these elements apart and find the right local Z orientation, which you can apply on the SV and K elements

Hey @keuj.84,

thanks for your comment. I have checked the orientation of the elements via dissamble model and these agreed.

However, the visual representation in my opinion is not correct, because the spring is oriented towards the global coordinate system and is globally oriented in the x-direction.

I have prepared the model more comprehensibly and in the following picture the knot numbers are shown:

Tangential bearing_1.gh (90.8 KB)

Hello @banisethfabio,
I think it is easier in your case to use hinges at the columns instead of zero length springs.
Did you try this?
— Clemens

Hi Clemens,

I was able to find a solution by increasing the spring length to a minimum (1cm). As a result, the springs have aligned correctly.