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Thread: Large models in RSAPRO

  1. #1
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    Default Large models in RSAPRO

    I want to analyse a steel structure model of 50000 m2 constructed area, distributed in 21 stories with concrete floors panels. The first problem appears when you want to create the mesh. To have accurate results (and reliable at the same time) you need the smallest size of the mesh (around 0.5 m), but I get the following errors:
    1. out of memory;
    2. a lot of panels aren't discretized (nodes are placed on the panel but they aren't connected );
    3. a lot of diagram errors;
    4. when making steel structure verification I get very big ratio values.

    What to do? My PC has the following configuration: i7 920, 6GB RAM DDR3 triple channel, 4 RAID 0 HDD, nVidia Quadro FX 1700, Win Xp 64Bit.
    I have also tested the structure on a Dell Precision T7500 with Xeon and ECC RAM and the problem persisted.
    If someone would advice me to check my model for mistakes, I already did several times and also other Robot users did that and they didn't founded any mistakes.

    Home someone from Autodesk will answer.

    Thanks in advance!

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    Default Re: Large models in RSAPRO

    "when making steel structure verification I get very big ratio values"
    That's probably due the big axial forces that have appeared if you used panels eccentrically connected with beams.
    Generally it's not a good practise to use surface FE with beam elements.
    Robot can't design directly those steel beams. The effort needed to manually design those elements is huge. There is an option for RC beams but gives poor results.

    As for the inability of robot to handle this big structure i guess you should try some other solver from preferences and see what happens.

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    Default Re: Large models in RSAPRO

    Quote Originally Posted by Marios View Post
    "when making steel structure verification I get very big ratio values"
    That's probably due the big axial forces that have appeared if you used panels eccentrically connected with beams.
    Not necessarily. For a beam subjected to axial force and bending moment, when making verifications with EC3 it use the formula 6.2.9.1.(6) and if the differences between the two moments are very big, then the ratio at 5th power will become very big, so that your final ratio can be immensely. And that ratio didn't appeared at the bottom of a column, it appeared at the last story column.

    Quote Originally Posted by Marios View Post
    As for the inability of robot to handle this big structure i guess you should try some other solver from preferences and see what happens.
    I have tried that already...no result..

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    Default Re: Large models in RSAPRO

    what kind of Floor model you have used to model floors and panels: shell, Flexible diafragm or rigid diafragm

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    Default Re: Large models in RSAPRO

    Quote Originally Posted by length zero View Post
    what kind of Floor model you have used to model floors and panels: shell, Flexible diafragm or rigid diafragm
    The structure don't have any RC wall. It has only RC floors, that were modelled as shell.
    Last edited by pascal.bogdan; 2010-05-31 at 02:43 PM.

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    Default Re: Large models in RSAPRO

    Are you trying to make floor to behaviour like as composite.
    I meant do you have used offsets for bars.
    In which manner do you have model the flors.

    Do you have try to reduce number of finite elements, mesh size from 0.5m to 1m. and if you have again problems.

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    Default Re: Large models in RSAPRO

    I had the same problem with meshing of panels( points are in panels but finite elements are not generated) before some months.
    But if remember it have been an incorrection betwen som of the panel edges.

    If your problem with mesh is in some floors delete them and replace with panels that have correct mesh from other floors by translating them.
    I belive that your abnormal results are caused from this case.

    But if all flors have incorrect mesh, idon't know what to say.

    Regards
    Z.G.

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    Default Re: Large models in RSAPRO

    Quote Originally Posted by pascal.bogdan View Post
    I want to analyse a steel structure model of 50000 m2 constructed area, distributed in 21 stories with concrete floors panels. The first problem appears when you want to create the mesh. To have accurate results (and reliable at the same time) you need the smallest size of the mesh (around 0.5 m)
    1. Reduce model size. Roughly counting you end up with 400000 finite elements which is a pain to handle. Some extra work on your mesh (like using 0.5m emmiters but the mesh size about 2.0m) can pay back.
    2. For big models it is recommended to limit visibility settings (switch off finite elements - open new window with one floor to examine FE mesh).
    3. Consider using "Calculation Manager" that allows to generate computational model and (optionally) run calculations with maximum memory available
    4. Eliminate other applications to free some more memory

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    Default Re: Large models in RSAPRO

    Quote Originally Posted by length zero View Post
    I had the same problem with meshing of panels( points are in panels but finite elements are not generated) before some months.
    But if remember it have been an incorrection betwen som of the panel edges.

    If your problem with mesh is in some floors delete them and replace with panels that have correct mesh from other floors by translating them.
    I belive that your abnormal results are caused from this case.

    But if all flors have incorrect mesh, idon't know what to say.

    Regards
    Z.G.
    The model is automatically generated without any errors, all the finite elements are well placed. There aren't any incoherent meshes. Only the model is too large.

    @Gazes

    I will try to make the changes that you recommended. Thank you!

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    Default Re: Large models in RSAPRO

    I'm waiting your recommandations, too. İm using RSA 2011 professionel. Im working on a big model 25-30-40 story and appears a lot error. first error out of memory. second error when try mesh 0.5 m. incoherent mesh warnings. my computer i7 intel, asus board 4 gb ram. 1 gb. ati, 2 gb hdd.

    whats the problem.????

    or best run robot version v20, v21 or rsa autodesk 2009, 2010 ????

    please give your advice... thanks.

    falconado_turkey

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