Sunday, April 19, 2009

Definition of Buckling Factor?

I need to know what exactly the buckling factor is, and how it relates to the critical load. for buckling in a column.

Definition of Buckling Factor?
Deformation of a material due to the pressure of a supported load.





The ratio of the length of a column to the least radius of gyration of its cross section is called the slenderness ratio (usually expressed with the Greek letter lambda - λ). This ratio affords a means of classifying columns. All the following are approximate values used for convenience.





A short steel column is one whose slenderness ratio does not exceed 50; an intermediate length steel column has a slenderness ratio ranging from 50 to 200, while long steel columns may be assumed as one having a slenderness ratio greater than 200.


A short concrete column is one having a ratio of unsupported length to least dimension of the cross section not greater than 10. If the ratio is greater than 10 it is a long column.


Timber columns may be classed as short columns if the ratio of the length to least dimension of the cross section is equal to or less than 10. The dividing line between intermediate and long timber columns cannot be readily evaluated. One way of defining the lower limit of long timber columns would be to set it as the smallest value of the ratio of length to least cross sectional area that would just exceed a certain constant K of the material. Since K depends on the modulus of elasticity and the allowable compressive stress parallel to the grain it can be seen that this arbitrary limit would vary with the species of the timber. The value of K is given in most structural handbooks.


If the load on a column is applied through the center of gravity of its cross section it is called an axial load. A load at any other point in the cross section is known as an eccentric load. A short column under the action of an axial load will fail by direct compression before it buckles but a long column loaded in the same manner will fail by buckling (bending), the buckling effect being so large that the effect of the direct load may be neglected. The intermediate length column will fail by a combination of direct stress and bending.





The 18th-century mathematician Leonhard Euler derived a formula which gives the maximum axial load that a long, slender ideal column can carry without buckling. An ideal column is one which is perfectly straight, homogeneous, and free from initial stress. The maximum load, sometimes called the critical load, causes the column to be in a state of unstable equilibrium, that is, any increase in the loads or the introduction of the slightest lateral force will cause the column to fail by buckling.
Reply:I aint quite sure but i thank when I eat lots a cornbread my knees start bucklin under my belly
Reply:The answer depends on many things.


What type of structure?


What is the geometry? (for instanct, thin walled cylinders are very sensitive to imperfections)


How is it loaded?


What is the application?


Are you using a linear eigenvalue analysis or a non-linear analysis?



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