Learning Forum

[Inan]

Hi there. I'm a final year student in my civil engineering degree. For my final project, I decided to do some finite element analysis for a suspension bridge. I chose to model the Humber suspension bridge using Ansys workshop design modeler. I'm encountering two problems with my model mentioned below.

1) I modelled my suspension bridge to scale using some measurements I got from a few reports. The bridge is around 2200m long. In mechanical, the forces I applied to my bridge is gravity, a pressure and some fixed supports at the end of the main cable, end of deck and bottom of the tower. When I try to solve my bridge, I'm achieving maximum displacements of around 700.18m. This I know for sure is not realistic and I cant seem to find a solution to this problem.

2) My second problem is currently my whole bridge except for my deck is modelled with BEAM188 elements and the deck is modelled with a SHELL181 element. I want to adjust hangers and main cable to be LINK10 elements. I cant seem to figure out how to do this.

[peteroznewman]

nI haven't looked at your model, but there are two things you need to prevent ridiculous deformations due to gravity.nDid you turn on Large Deflection? That must be On to allow tension to build up in the structure.nYou may also need to define an initial stress in the main cable to represent the final tension. The main cable could have an INISTATE command to create pretension in the entire length as gravity ramps on in step 1 of the analysis. The hangars could use Bolt Pretension to lift the bridge after gravity has created tension in the cables to level out the road surface.n

[Inan]

Thank you for the reply.nSo I turned on large deflections and I experienced an error where it suggested that I turn off small sliding at my contact. I turned that off however I am still getting a error. Below is a picture on how the model looks now, as well as the errors at the bottom of the image. These changes made my model unstable and I cant seem to figure out how to solve this issue.nDo you have any suggestions on how I can solve this issue. I would greatly appreciate it. I have attached the updated model below if you would like to see. The original model still remains attached above if you would like to look at that instead. Thanks again in advance.n