# Calculating Moment Capacity of A36 steel plate

1. Mar 14, 2013

### dtbernar

I am using an 8" steel plate as a beam that will undergo moment forces and deflections. I am not sure how to calculate the maximum moment capacity of a plate like this. I think that the deflection would = Fb*L^3/(48*E*I). Does this look correct?

I know how to calculate the max moment in the beam, but I need to know the nominal moment strength. Does anyone know the equation to do this? I believe that I will have to divide this by 1.67 for ASD allowable strength.

2. Mar 14, 2013

### jehake12

Do not use the information below if you are designing/building something that could impact public works or put people in danger. Stop immediately and hire/contract a licensed Civil/Structural professional engineer in your area:

Depending on your application, here is what is used for buildings and other structures:

The allowable flexural strength for Rectangular Bars (Mn/Ωb for ASD) can be determined by AISC Steel Construction Manual Thirteenth Edition: Chapter F Design of Members for Flexure if it satisfies the assumptions/requirements in the general provisions (I'll let your look those up.) Section F1 (general provisions) sets Ωb=1.67 for ASD. Section F11 governs nominal flexural strengths, Mn, for rectangular bars bent about either geometric axis. The two limit states are yielding and lateral-torsional buckling. The lower of the two calculated Mn values should be used in your calculation of allowable flexural strength.

These allowable flexural strengths are intended to be used with the load cases generated by the applicable building code, and when that is not present, use the applicable ASCE07 load combinations.

3. Mar 15, 2013

### nvn

dtbernar: Is your plate bending about its minor axis or major axis? If it is bending about its major axis, see post 2. If your plate is subjected only to static loading, in a building, and is bending about its minor axis, then you would want to ensure the applied moment, M, does not exceed 0.25*b*(t^2)*Sty/1.67, where b = plate width (mm), t = plate thickness (mm), and, for your material, Sty = 250 MPa.

Last edited: Mar 15, 2013