Steel Design - Effective lengths of columns - SD424

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  • Опубликовано: 11 дек 2024
  • This video overviews how to determine the effective length of columns, and how a single column can have multiple effective lengths.
    Copyright Stellenbosch University

Комментарии • 33

  • @hasey2177
    @hasey2177 3 года назад +1

    I really appreciate the way you explain it. I think you have more experience.

  • @mahmodmohamadmahfoud658
    @mahmodmohamadmahfoud658 3 года назад +3

    I believe that For the Ly, lateral supports only prevent outer flange from moving in & out. so, in order to consider Ly = the girt spacing; flange brace is mandatory to constrain the inner flange movement as well

    • @firesun
      @firesun  3 года назад +2

      This is a good point. To get an accurate value of KLy with multiple side connections a finite element analysis or testing may be required. However, in most cases connections in real structures are much stiffer than pins (e.g. a T-cleat with 4 bolts into a girt and lots of sheeting on a face). Also, the web adds stiffness and links the flanges together. But yes - if you had a pure pinned connection at the lateral restraint, and a thin web or very deep section it may be under-conservative to consider a restraint from a single flange. However, the torsional resistance will also capture this behaviour to some extent. For compressive buckling the entire section has to move sideways, and only one flange can moved. More detailed analyses would needed to highly loaded or complex structures where such behaviour is important.

    • @mahmodmohamadmahfoud658
      @mahmodmohamadmahfoud658 3 года назад

      @@firesun Impressive 👏
      Thank you, appreciate it.

    • @mtbmcc2493
      @mtbmcc2493 3 года назад

      Agree

    • @mirzanaushadbaig9147
      @mirzanaushadbaig9147 2 года назад

      @@firesun Ly in case of I beams is different for both flanges. But for tubular sections Ly can be as you have explained in the lecture as the flanges of tubular sections are firmly connected with two webs.

  • @zian.2493
    @zian.2493 4 года назад +3

    2:14 can you correct/ verify clearly where direction it buckles?

  • @me09hha
    @me09hha 4 года назад +1

    Great explanation

  • @nicolasjativa1441
    @nicolasjativa1441 Год назад

    So well explained!!!

  • @zian.2493
    @zian.2493 4 года назад +1

    Can you please make a video on how to counter this buckling effects ..like providing stiffeners what type of stiffeners.

  • @sourabhshrivastav3964
    @sourabhshrivastav3964 3 года назад

    Great Explanation

  • @Alias102.
    @Alias102. Год назад

    Would the effective length factor K change if the column were to be restrained say twice or once along its length.

  • @sothattheng8624
    @sothattheng8624 4 года назад

    Thanks for sharing!

  • @mohanadhabh772
    @mohanadhabh772 3 года назад

    man you are great >>>>> thanks

  • @ibrahimalbaz2595
    @ibrahimalbaz2595 4 месяца назад

    i have a question regarding the Lx, you said that the girders will move with the column if there is a buckling in X-axis but the thing is, these girders are probably attached to another column maybe, so shouldnt the Lx becomes less same like Ly ??

    • @firesun
      @firesun  4 месяца назад +1

      Normally the girts are quite slender, and also simply supported, so will typically provide limited lateral support. Also, the column next door will often be loaded to the state so may be buckling at the same time, so cannot be relied to provide stability. However, there are detailed design methods to evaluate whether members can be considered to provide lateral support.

    • @ibrahimalbaz2595
      @ibrahimalbaz2595 4 месяца назад

      @@firesun thank you for your explanation

  • @tominmathew344
    @tominmathew344 9 месяцев назад

    Sir, can we cut off the Ly as the distance between the channel section if it’s a moment frame.

    • @richard_walls
      @richard_walls 8 месяцев назад

      Normally the length is taken as the distance from centre to centre of supports.

  • @ahmedyaqub2377
    @ahmedyaqub2377 Год назад

    How can I prevent cracks in partition walls due to deflected steel structural beams' interaction?

    • @firesun
      @firesun  Год назад

      Stop the beam from deflecting (i.e. stiffen it) or isolate the members from each other.

    • @ahmedyaqub2377
      @ahmedyaqub2377 Год назад

      @@firesun Regarding isolating the members from each other is there any code mentioned that, like IBC or AICS Standard, Please help me

    • @firesun
      @firesun  Год назад

      @@ahmedyaqub2377 - You simply need to install a soft material that can accommodate the movement, and keep the wall and beams not connected to each other.

    • @ahmedyaqub2377
      @ahmedyaqub2377 Год назад

      @@firesun Dea Sir, there is a controversy in our company that insulation is not required and it is possible to make the non-loading partitions directly contacted with steel truss without separation, so I need a paragraph in the code that stipulates that the isolation must be achieved

    • @firesun
      @firesun  Год назад

      @@ahmedyaqub2377 You will not normally find this in a code. However, if a steel struss moves more than a wall can allow then the wall will crack. It is based on physics rather than codes.

  • @Kiwistoicist
    @Kiwistoicist 6 месяцев назад

    Did you get ly and lx in the wrong way? the weak axis is Ly which lateral supports only at top and bottom

    • @firesun
      @firesun  6 месяцев назад

      The girts provide lateral support about the weak axis so Ly is shorter.

  • @ranjanty
    @ranjanty Год назад

    Hi, could you please help me?
    I have a 48inx24in stainless steel table with tubular legs that are 32.75inches high.
    I want to increase the weight capacity which is 500 something lbs. If I fill the legs with concrete and a piece of rebar would that increase the weight capacity of the table? Maybe to 800 lbs.
    I'm 70 and I'm no longer able to figure it out. Thanks to anyone who chooses to help ❤

    • @firesun
      @firesun  Год назад

      Sorry, my brain does not work as well in lbs and inches. Strength is often governed by member capacity and also connections. Hence, if you strengthen something you also need to ensure that the connections between members are sufficient. As a rough rule of thumb if you take the area of concrete at around 40% of the strength, say 20 MPa for a low quality concrete, and add on strength of the rebar at 60% of its yield strength you have a ballpark estimate of the capacity. 800lbs is not that much load for a steel and concrete structure, especially if there are 4 legs.

  • @structuralchannel2507
    @structuralchannel2507 2 года назад

    Hii sr what will be effective length of free standing column with one end fixed other free

    • @firesun
      @firesun  2 года назад

      K=2.0 for a cantilever normally

  • @structuralchannel2507
    @structuralchannel2507 2 года назад

    Sr can you send a way to contact you?

  • @sensennsen
    @sensennsen 2 года назад

    "nothing is fixed in real life, with both the tolerances and the rest of it..." witty