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RCC column design

Ramakumar Pechetty

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

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  • in reply to Ramakumar Pechetty
    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.



  • Offline 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

  • Offline 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

  • Offline 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.



  • Offline 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

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