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Deformation, stress, and strain problem.

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Homework Statement


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


Homework 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?


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.
 

Answers and Replies

  • #2
PhanthomJay
Science Advisor
Homework Helper
Gold Member
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Homework Statement


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


Homework 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?


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.
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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