Why Choose an I Section Over a Square Section for Load-Bearing Applications?

[Analysis]

Dear all

Apart from cost saving (or reduction in material)what is the technical advantage using I section instead of square section?

My application is,section is going to be simply supported to the static load.myself awared that I section is good for bending loads.Instead i am using square section,so my area moment of inertia will be high,the bending stress would be low.

Kindly comment the above subject.

Thanks
Prakash

 

[Pkruse]

I use square sections when I want a cleaner or more attractive design, or when I have a bending component in the other plan. Less surface area collects less dust and is easier to wash down. When galvanizing less surface area uses less and is easier to ensure a uniform coating.

 

[HallsofIvy]

The most important reason to use an "I beam" (or "I section") is that it has much less volume and so much less weight than a square section of the same dimensions. And, since such things as "bending moment" depend upon the length in varying directions rather than volume, you don't lose strength.

 

[FAlonso]

I beam definitely is an obvious choice for situations where bending moment is of prime concern. As long as following conditions are not true, you can always go for I-beam:

1: Manufacturing: Normally i beams are not available in smaller section and hard to join (welding etc)

2: I beam is a poor choice where you have loads acting transversely to the length of beam.