The slenderness in steel design of Code AISC 360-16

Hi, i am working a model for structural steel design. There is a mistake to check the slenderness and the compression member in code of AISC360-16.

The mistake is that the when I defined a length for LZ, but the slenderness in Y direction LY is equal to LZ, not the default length. As you know, the beam is supported by hbrace and infill beams in weak axis.

Does anyone has this problem? 

The STAAD.Pro version is V22 update 6. 

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  • Thanks for you response. 

    The question of mine is that to calculate the slenderness regarding weak axis of member, the calculated length of weak axis is not taken as LY which is not defined in design parameter.  

    This is regarding under compression, not tension.

    In current version of STAAD.Pro, if a member was supported with some infill beams and or some horizontal braces in weak axis, and the LZ is defined in design parameter, the software is taken LZ to calculate slenderness in weak axis. Actually, the LY shall be taken as physical length.

    I don't know the description of question is clear or not.

  • Slenderness check is for Critical case, regardless what user specify LZ or LY.

    If Lz is bigger than Ly than Slenderness check will performed using Lz.

    If Ly is bigger than Lz than Slenderness check will performed using Ly.

  • The slenderness ratio is regarding two perpendicular direction of section, Lz/rz, and LY/ry. The compression capacity is controlled by the minimum slenderness ratio. If maximum Ly and Lz to be used to check both direction, the design results are to be over-design. The OWNER shall be challenging the structural engineer. 

  • The original post is only regarding slenderness check.

    So I replied the slenderness check will be done by longer length.

    The slenderness check is completed and it is not related directly with compression capacity check.

    Ofcourse the Lz and Ly will be used calculate the compression capacity.

    However now you mentioned about compression capacity, The Compression capacity for each axis will be calculated with each Lz and Ly separately.
    But the minimum capacity will be used for design results. Becasue it will be the governing limit state.

    Design is not over design, it is exact design.

    If you look into the design result with track 2, then you would understand what I said