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Finding the value of an UDL

  1. May 15, 2008 #1
    i am trying to find a UDL of a beam, with 10m span. It was a cross section of 200mm by 200mm of concrete and reinforced with 5 steel reinforcing bars of 20mm diameter. i have both E's. is there a formula that can be used to find the UDL of a beam.
    thanx alot
    cheers for ur time
  2. jcsd
  3. May 16, 2008 #2
    To find the UDL of the beam itself (No external loading) you would need to know the density and volume (which you can calculate) of each material, and use the equation:

    mass = [tex]\rho[/tex]V

    Then Force = 9.81m= 9.81[tex]\rho[/tex]V

    This is assuming the beam material is homeogenous, which from what you've said the concrete is reinforced by a steel grid, and you might have to produce a shear force and bending moment diagram. I'm not sure if thats what you were asking?

    There is also the beam bending equation,

    [tex]\sigma[/tex]/l = M / I = E / R

    Which might not be that helpful in this case.

    And there are also equations for equivalent force of a UDL in different loading set-ups (such as simply supported/ cantilever)

    I'm not entirely sure what you're asking though.
  4. May 16, 2008 #3
    thanx for the reply.
    my beam is has a pin at the left hand end and a roller 4m in from the right had side. so theres a 4m overhang, and the UDL (w) is over the whole beam. if i have the density, then i would know how to work it out through that, but i dont have the density. all i got is the cross section showing the bars in the concrete, the E's of both materials, and the tensile stress at which the concrete cracks which is 4.5 MPa. thats all the values i have.
    so i wanna know how to find the UDL(w) using the values i have.

    thanx alot for ur time
    cheers champ
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