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Steel Box Section strength for climbing wall

  1. Sep 23, 2014 #1

    I'm planning to build a climbing wall outside my house, attached to a concrete wall.
    The climbing wall would be 3 sheets of 18mm plywood (each about 30kgs) - each 2.5m x 1.22m (8ft x 4ft). With the boards set out 2.5m wide and stacked 3 high to give a max height of 3.66m (12ft).
    I want the wall to be adjustable, to pivot out to be able to climb overhangs. Fixing the top to the wall with chains.

    I'm thinking of creating a steel frame to fix the boards to, someone suggested using 50mmx50mmx3mm steel box. But I'd like to calculate the loads and work out the best dimension of steel.
    The simplest design would be 2 uprights and 4 cross-beams to fasten the boards to.
    How do I calculate the forces on the steel if the wall is leaning outwards, probably 20 or 30 degrees ?
    Maybe I'd need a third upright in the middle, to give it vertical rigidity ?

    Any help much appreciated, I've not done any of this mech eng before. I did a Physics degree many moons ago, and never found it much us in everyday life!

  2. jcsd
  3. Sep 24, 2014 #2


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    Science Advisor

    Welcome to PF.

    The simple answer is that you need to consult an insured engineer. Why?
    How many uninvited people might possibly be on the wall at one time? Can the wall support the climbing structural modifications with multiple climbers. The wall will tend to fall on the climbers if they are far out from the vertical wall. What wind rating will it need to be designed to withstand?

    Attempting to calculate such a complex structure yourself would be dangerous. PF would not want to be associated with the liability of what is clearly a challenge for a consultant engineer with insurance.

    I suspect that a sensible economic solution would be to make a self supporting framework that sits near the wall but is not actually attached to the wall. That eliminates many of the obvious risks and liabilities. The self supported frame could then be C or U shaped in plan, so the climber(s) could be safely inside the structure only.
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