During construction, field tests were conducted to assess thesuitability of the column to
withstand a safe buckling load of 2.5 kN assuming a factor ofsafety 4 using two different hollow
columns made up of steel and concrete. Both columns have same crosssection but varying length
and different support conditions. Steel column of length 3 m havingexternal diameter 40 mm was
tested with one end fixed and the other end hinged, when subjectedto a compressive stress of
0.0045 MN/cm2 shortens by 3.6 mm.
If the concrete column was tested under similar loading conditionswith one end fixed and other
end free considering modulus of elasticity of concrete equal to 128GPa, what will be the
corresponding length of the column required? As a design engineerhow do you choose the values
for the thickness of both columns and the length of the concretecolumn? What will be your
interpretations regarding the relationship between the supportconditions and the buckling load
based on the test results?
