Buckling is defined as a mode of failure under compression of a structural component that is thin with respect to its length (slenderness).
Let's understand How?
• Take a (Playing/Visiting) Card and hold it vertically.
Apply Force axially, and it will soon start bending in out-of-plane.
This is called Buckling.
In above-shown example, boundary conditions were Pin - Pin, so, curvature starts from ends. Hence, Effective length is nothing but the original length in this case.
So, effective length factor k = 1.0
The force at which, element is susceptible to buckling, is called as buckling force or strength.
With the change in effective length, buckling force will change dramatically
That effective length can be altered by two options:
1. Boundary condition - As discussed, with the change in support(s), the starting point of curvature will shift, hence change the behavior.
2. Providing lateral Support - Let's understand how?
Place fingers on both side of cards, and then compress it. Now, it can take comparatively more force then previous case. And that's how. you can optimize size of long columns by placing lateral support
Quick way to understand buckling is, hold all cards to gather and try to apply compressive force. Though those are made of paper or plastic, they may cause pain in your hand, but won't bend.