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RCC column design

Dear sir,

What does it mean when the out put of staad for column design says that " The number of iterations exceeded 500" ?

regards

ramakumar

13 Replies (Most Recent Reply)

  • Can you attach the STAAD file. You may have to zip the file before attaching


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  • In reply to NIHESH.N:

    Mr. Nihesh.

    I am attaching the staad file as told you. I am using the staad pro version 20.07.03.16.

    The out put file for column design for some columns is saying" **** ITERATIONS EXCEED 500.
    WHILE CALCULATING COLUMN MOMENT CAPACITY.

    I would also like to know whether any report /data is available listing the errors,warning and the reasons for their occurance.

    regards

    ramakumar

    PLOT NO.46 (170409)-1.zip
  • In reply to Ramakumar:

    In STAAD for column design as per IS:456 code, the location of neutral axis is determined. It follows the first principle. The process is a iterative one. The maximum nos. of iteration set for the process 500. So for his case the program fails to find out the neutral axis of the column section provided. You may either change the section size of increase the default Max. % of reinforcement by using RRATIO parameter(which is set to 4%). It should be noted that it has been a common practice for the design engineer to go for maximum of 4% steel to facilitate the proper bonding between steel and concrete. So increasing the maximum of % steel would not be a good idea.


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  • Hi

    How a RCC Column subjected to Axial Tension plus biaxial bending moment is designed ? Is it the same way as for Axial Compression with biaxial bending moments.   ....Concrete portion is not working in tension case..    Please help me out.

     

    Bijay

     

  • In reply to NIHESH.N:

    Dear Sirs,

        Sorry for digging up such an old topic. But I came across this thread on searching for this warning. I am confused by this response. Theoretically, I would assume that if the warning is an indicator of member having failed, the output should not include results (Steel reinforcement required). However, the output is including required reinforcement (and it is not necessarily near 4% - in some cases it is less than 3%). Please clarify.

    Thanks in advance

    Arunkumar Srinivasan

  • In reply to Arunkumar Srinivasan:

    Dear Sirs,

        Request clarification for my query above... Further, I am clarifying that this is not in reply to Mr. Bijay's post just above mine, but with respect to Mr. Nihesh's post (just above Mr. Bijay's post)

    Thanks again

    Arunkumar Srinivasan

  • In reply to Arunkumar Srinivasan:

    The program is automatically increasing % of Reinforcement and starting with a new round of iteration. After 500 iteration, it fails to calculate the capacity. This message indicates that column design in incomplete. The program is able to calculate the % of Ast required from the column. Then, it tries to distributes the reinforcement. After providing the reinforcement, the program is calculating capacity based on the provided reinforcement. It fails in this process.


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  • In reply to DSANJU:

    Dear Sir,

          If the column design is incomplete, why is STAAD displaying the steel requirement along with the warning? Are you implying that the Column design is safe, but STAAD is unable to compute the IR?

    Thanks in advance

    Arunkumar

  • In reply to Arunkumar Srinivasan:

    If you get this kind warnings, it indicates that the program is unable to report IR correctly.


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  • In reply to DSANJU:

    Dear Sir,

         Based on your post, I am now understanding that this warning "The number of iterations exceeded 500" does not mean that member has failed. It means member has passed but capacity ratio parameter IR could not be calculated accurately for the same.

        Please confirm this is correct.

        Also, I notice your posts indicate you are part of Bentley's Select Support staff. Hence, this would be equivalent to official confirmation from Bentley on the same. Hope I am correct

       Sorry for any inconvenience but reason I am asking for this is that this warning is present in my STAAD output which I need to submit for cross-verification and an official explanation for this warning could not be found earlier to my satisfaction.

    Yours sincerely

    S Arunkumar

  • In reply to Arunkumar Srinivasan:

    The warning doesn't stop the program to calculate the area of steel required for the column. But, it is an clear indication of the fact the IR can not be computed by the program. I am from Bentley Technical Support Group.


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  • In reply to DSANJU:

    So, I can use the output reinforcement detail as such without need to resize the column right?

    Thanks again

    Arunkumar

  • In reply to Arunkumar Srinivasan:

    Ideally, you can work with the Ast required. But, you need to go for different bar distribution. IR check with the provided % of reinforcement has to be checked manually.


    This is a test

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