Moving Loads on Bridge Deck - Slow Model

[ALJohns]

Hi Guys

I am currently modelling an existing bridge to AS5100. The bridge is 8 lanes wide and approximately 70m long.

I have set up a moving load in each lane for 3 different vehicle types (total of 24 moving cases). The step increment for each moving load is 0.5m. I have not added any case combinations to the model yet.

I expected the model would take some time to crunch the numbers, but model takes 30-60min to run just to generate the moving load forces, and then the model has become frustratingly slow to edit with long delays between each click. My questions are:

1. Is the slow model due to the computational effort required, or are there modelling issues that are causing it to slow down (file attached)?

2. What is the best way to approach this analysis? I have read a previous post which suggests generating moving loads in RSA, then exporting to excel for combinations. I'm happy to do this, but I am having trouble just generating the results from primary in the first place.

3. Are there any settings/Job preferences that can be adjusted to help speed things up?

Any help or other ideas would be appreciated.

Thanks

Aaron

[Rafal.Gaweda · Accepted solution]

I encourage you to watch 14th webinar

http://forums.autodesk.com/t5/robot-structural-analysis/robot-structural-analysis-webinars/td-p/5523...

Hints:

- use panels instead of claddings (to change already existing cladding onto panel please assign panel thickness to it)

- run vehicles on "Selection" (use selection of all panels)

My test : your model with panels with 2m mesh + 10 moving load cases on "Selection" of all panels -> Model Generation 1-2 minutes

[ALJohns]

Thanks Rafal

I watched the Webinar and found it helpful, particularly the 'live examples'.

I have changed the cladding to FEA panels as you suggested, however in locations where the moving load contour line is close to the beam lines, I am getting a very fine mesh. Is there a way around this? Also, how does are the moving point loads applied to the FEA slab (does the model generate nodes at each point where the vehicle point loads act)?

Cheers
Aaron

[Rafal.Gaweda · Accepted solution]

however in locations where the moving load contour line is close to the beam lines, I am getting a very fine mesh. Is there a way around this?

http://forums.autodesk.com/t5/robot-structural-analysis/meshing-into-robots-2012/m-p/3310703#M2404

Also, how does are the moving point loads applied to the FEA slab (does the model generate nodes at each point where the vehicle point loads act)?

No, program distributes internally such point load onto nearest nodes.

[ALJohns]

Hi guys

I am now exporting tabulated data from robot and manipulating it in excel to combine design actions and complete member checks.

Ideally, I would like to export one large table which contains all the data I need to complete the analysis.

The table output under the "values" tab is exactly what I want - it provides forces/moments for each characteristic point of every bar in the model, and general data columns can be added to identify the members. However, when this table includes moving loads, it only captures the envelope values for each force component - these maximum/minimum envelope values don't necessarily occur simultaneously. 

I know that I can go to the "envelope" tab, filter the moving load cases, and show forces with concomitants... but then I have to combine and integrate multiple tables in excel. Is there a way to get all this data in one table? Otherwise, what is the best way to export to excel to achieve this?

Also, as an aside, how can I export the envelope with concomitants to excel without the '<<' and '>>'?

Thanks again for your help

Aaron

[Artur.Kosakowski]

You may consider the conversion the positions of moving loads into simple load cases and use them instead of  moving load components to export the table to Excel.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.