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## Homework Statement

how the author found the maximum moment = 0.29MNm ? is there any formula ? how to find it in this question ?

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how the author found the maximum moment = 0.29MNm ? is there any formula ? how to find it in this question ?

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SteamKing

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Of course there's a formula. That's what beam tables are for - too look up things like the maximum B.M. without having to work them out from scratch all the time.## Homework Statement

how the author found the maximum moment = 0.29MNm ? is there any formula ? how to find it in this question ?

## Homework Equations

## The Attempt at a Solution

Here is a set of typical beam tables:

http://www.awc.org/pdf/codes-standards/publications/design-aids/AWC-DA6-BeamFormulas-0710.pdf

Your beam is Figure 1, page 4.

BTW, the calculation of the total weight of the wall above has a small error. W = 0.145

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the shape is rectangular cross section , am i right ? why the moment shouldnt' be a(b^3) / 12 ? but , a(b^2) / 8 ?Of course there's a formula. That's what beam tables are for - too look up things like the maximum B.M. without having to work them out from scratch all the time.

Here is a set of typical beam tables:

http://www.awc.org/pdf/codes-standards/publications/design-aids/AWC-DA6-BeamFormulas-0710.pdf

Your beam is Figure 1, page 4.

BTW, the calculation of the total weight of the wall above has a small error. W = 0.145MN, rather than 0.145 kN.

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SteamKing

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The problem is trying to figure out the dimensions of the cross section of the beam so that max. bending stress is limited to 7.5 MPa.the shape is rectangular cross section , am i right ? why the moment shouldnt' be a(b^3) / 12 ? but , a(b^2) / 8 ?

Remember, in bending, σ = M ⋅ y / I

It is postulated that the beam supporting the brick wall is twice as deep as it is wide, or w = b and d = 2 ⋅ b, and I = w ⋅ d

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