What is the overstrength factor used on the Allowable stresses Table for aluminum beam

[structure567]

I need to do some aluminum beam design and had some questions on Aluminum Design Manual(ADM) Part VI Table 2. This table shows the allowable stress but is shown as F/Ω. It does not specify what the omega value is... Does anybody what the over strength factor that is used?

 

[r13]

If this table is for allowable stress, which expressed in F/Ω, then is that necessary to know the value of Ω. It could be a varying safety factor, and can be derived by F/allowable stress listed in the table.

 

[structure567]

I would like to know the value because I'm not sure which safety factor is applied. I dont know if I'll need to apply another safety factor on top of the one already applied.

 

[r13]

I've explained how to derive the value of Ω in my post, provides you know what is "F" representing, and are certain F/Ω is indeed the allowable stress. Try some cases to see if the resulting safety factor make sense or not.

 

[brut3]

You'll need to reference each section of the ADM specification to see what the Omega factor is. Below is a snapshot from Chapter F which governs the design of members for flexure. As you can see below you'll have a couple different omega values depending on your governing failure mode and what type of structure you're designing.