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### Course: Properties of matter (Essentials) - Class 11th>Unit 2

Lesson 6: Applications of elastic properties

# Why use I beams in construction?

When constructing buildings, why do we always use beams which have a cross-sectional shape of I? Let's explore this intuitively in this video. Created by Mahesh Shenoy.

## Want to join the conversation?

• why in the centre there is no stress ? why is it taken zero ?
• because at the ends the tensile and compressive strength are maximum at centre they will act at half magnitude so these two will cancel out and the total stress would come out to be almost zero
(1 vote)
• Why we don't use beams of 'X' shape with two flat surfaces on the top?
• well i am not sure but in x shape with flat surface not maximum area would be removed from the centre and our main is to remove it from centre not from sides
(1 vote)
• If The end points are fixed and then if the beam bends downwards

Then shouldn't the line joining the end points on the upper surface of the beam become a downwards arc?
If yes then wouldn't the distance of the arc be greater than the distance joining the same two points by a straight line?
Then wouldn't this mean that the upper surface is also extended?

I understand that the top surface is in compression when we bend something like that but the end points also come close in such a situation.
(1 vote)
• wont the flangs( the top and bottom of the i beam ) bend more?
(1 vote)