Replace the engineer’s I-Beam recommendation with a different one

beamdeflectionsteel

I'm removing a load bearing wall and the structural engineer recommended a W8x15 steel I-beam. It would save me a lot of effort if I could use a 6" beam instead. So I'm trying to calculate the deflection of the W8x15 beam and then find a W6x?? beam with similar deflection.

I've found the specs for various wide flange beams here, but I can't find a max deflection equation that uses the elastic section modulus provided in the specs.

So, can someone point me in the right direction?

Best Answer

I think I figured it out. I was thrown off by the Elastic Section Modulus.

Anyway, the deflection is calculated using the following parameters:

W = load

L = length

E = Young's Modulus

I = moment of inertia

And the equation for max deflection is:

a

I'm trying to find a beam with the same maxdef or smaller. I can ignore W and L because they are the same regardless of I-beam. Young's Modulus E is a property of the steel used, so it is also the same regardless of I-beam and can be ignored (this is what I misunderstood). This means, the only variable I have to worry about is I. I can see in the equation that I is part of the denominator, so if I increases, deflection decreases. So I just need a W6 beam with a larger I than what the W8x15 beam has.

Final answer: The only W6 beam with a greater I than the W8x15 beam is the W6x25,

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