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Homework Help: Deformation, stress, and strain problem.

  1. Apr 20, 2014 #1


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    1. The problem statement, all variables and given/known data
    A 24in diameter concrete column, at tenth story of an office building, is supporting the flat roof slab is subjected to a wind uplift load of 50.00kips while carrying a factored
    compressive force of 120.0kips. the column is 10.00ft long. Assume elasticity of concrete
    to be 4200ksi and the ultimate compressive and ultimate tensile strength as 2.400kis and 0.2000ksi respectively. Determine:

    Diameter: 24 in
    Wind uplift load: 50 kips
    Compressive force: 120 kips
    Colums length: 10 ft
    Concrete elasticity: 4200 ksi

    Area (A): 452.39 in^2

    2. Relevant equations
    a) The axial compressive stress from compressive force only
    b) The axial tensile stress from wind action only
    c) The net stress
    d) The deformation of the column
    e) The strain in the column
    f) The factor of safety? Is the column safe? Check whether the roof is carried away or not?

    3. The attempt at a solution
    A = 0.2653 ksi
    B = 0.1105 ksi
    C = 0.1547 ksi

    Sorry, but I am not sure if my answers are correct.
    Also I don't know how to solve d, e, and f.

    Thanks in advance.
  2. jcsd
  3. Apr 21, 2014 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Your answers A and B look good, also C, but you should indicate for C whether net stress is compression or tension.

    For deformation and strain, there are formulas you should look up for members under axial tensile or compressive loads.

    For F, compare actual ultimate stresses to allowabale ultimate stresses to see if the column is safe.
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