Objects:
To determine the buckling loads for various columns having different end fixing
conditions and lengths. To compare the experimental values found with calculated
values.
Apparatus:
Box tester, Quantity of steel rods, Assorted masses.
Procedure:
Set up the box tester with rods using the required types of end fixing combinations.
Measure the rod diameters and lengths, taking into account the end fixing method.
For each type of fixing gently apply axial loading via the carrier unit in 125 N (28 lb)
increments.
Record the buckling mode and the load at failure for each fixing method.
Calculations:
• Check the transitional slenderness ratio
Sy
E
r
2 *
Le 2p = ?
?
? ?
?
?
• and the slenderness ratio ?
?
? ?
?
?
mr
L
• Use the appropriate formula for either short or long columns to find the
theoretical failure load.
• Plot a theoretical graph of applied load versus column length for the three end
fixing modes. Given that Esteel is 210 Gpa.
• On the same graph show your experimental results for each test over an error
band range (which may be as large as 125 N or 28 lbs force).
• Compare the experimental and theoretical results for each type of end fixing.
Results:
This is an individual report. Submit a full formal report in the recommended format
of the experiment and in it plot your graphs, as shown over, to illustrate the
comparison of theoretical versus your experimental findings.
Comments:
Comment on the experiment and in particular on facets such as:
• Accuracy of the test
• Human aspects eg gentleness of loading
• Effects of eccentricity in loading
• Assumed value of Modulus of Elasticity
• Effects of end fixing
• Homogeneity of the column material
• Failure mode
• Determination of failure point