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How is this calculated

How is this calculated

RE: How is this calculated

It's the distance used to calculate the moment. I.e. 60.32 x 19.5 = 1,176.2

Presumably the value would be 1,176.3 if they showed the distance to its fourth digit.

RE: How is this calculated

Kind of hard for people to tell by the picture you provided..... but it appears to be the center of the applied load.

RE: How is this calculated

(OP)
That actually was a great help. Thank you guys for interpreting.

RE: How is this calculated

(Moment B-B)/(Force) = y bar. I’ll bet there is some other useful info. on the page, which you copied a part of, which would give us a clue about what your problem is. You really have to be able to define your problem better than you have, or maybe you shouldn’t be doing those kinds of problems. We speak engineering here, and maybe you should too. smile

RE: How is this calculated

Yes, it is just the height above the ground to the assumed point of wind loading.

RE: How is this calculated

(OP)
Guys,
I am actually trying create a spread sheet for this calculation. Thats the reason I have to understand couple of these values & how they were calculated.
From your help, I understabd the formula is basically. I have attached better picture.

moment=force x distance

With this I am able understand all the values for the column "Momemt at B-B".

But, further down, there is a calulation for moment at A-A.
here I don't understand the numbers red circled numbers 16.09, 10.09 & 7.3
Are these the distances from point of load application to Section plane A-A?

Also, why is the green circled force changed. Do you guys think this is mistake ?

Thanks

RE: How is this calculated

Yes, looks like a mistake. All calculations need to be checked, and this one wasn't. The red numbers are probably correct, but all the dimensions are not shown on the elevation.

RE: How is this calculated

Is it really a good idea for you to be setting up a spreadsheet for other people to plug numbers into when you don't know the basics of taking moments about an axis?

Yes, to find the moment at A-A you multiply the forces by the distance of the centroid of each force from the axis.

And yes, the number that is changed looks like a mistake; you should tell whoever gave you the drawing.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

RE: How is this calculated

By back-calculation, the vertical distance from Section B-B to Section A-A is therefore 3.41', so 16.09', 10.09' & 7.3' are the distances of ý‏­ (in table) LESS 3.41'.
­
The value of "93.06" in the moment at A-A calc should be the value of "193.06" from the table - typo error!

RE: How is this calculated

Am I the only one who doesn't see green circles on the attachment?

RE: How is this calculated

nope ... thought it was me ... maybe it's an Explorer thing ?

another day in paradise, or is paradise one day closer ?

RE: How is this calculated

(OP)
Thanks a lot guys. Well, i thought of using green color (so, i wrote green). But, the snipping tool has only 3 colors to choose from. :)

Normally, I use FEA tools and get done with. This way, I have really lost touch with basic calculations. Also, I don't want ask too many questions at one point, that's why I am asking in parts.

Question : Torsional Moment
I understand that this the kind of force generated due to effect of wind force on the element like a Banner, arm or a signage that sticking out from the center line of the pole. Thus generating the twisting effect on the pole (torque)

1. I see that the 183.16 is the force on the banner, but whats the value (2.58) underlined? I guess its the horizontal distance from the pole center to the center of the banner (thanks oldrunner).Also I looked in aashto code, probably its very basic, that's why its not showing it there.
I would appreciate if you can help me with where in aashto LTS i could find this.

2. Is there a any where online a revision history of aashto code LTS. I need to know what changed from LTS3 to 4 to 5 to 6. Is it documented anywhere.

3. I know that EPA is calculated by area x coefficient of drag. Is this a project area or surface area

I have included the spread sheet I have so far.

RE: How is this calculated

personnally i'd call it "over-turning moment" rather than "torque" ... torque implies axial twisting to me.

another day in paradise, or is paradise one day closer ?

RE: How is this calculated

ok, looking at your pic, it is a torsion, 'cause the banner is on one side of the pole. i'd interprete the 2.58' the same way (no dim'ns provided to verify.

sect A-A looks to be 3.41' above the ground (sect B-B) ... in the calc (with the circled numbers) 93.06 should be 193.06, and 7.3 should be 7.09 (to be consistent with the other parts of the calc.

another day in paradise, or is paradise one day closer ?

RE: How is this calculated

a simple way to verify Maa = Mbb-512.7*3.41' = 5823.1-1748.3 = 4074.8 ft.lbs

another day in paradise, or is paradise one day closer ?

RE: How is this calculated

Apparently, whoever filled in the table has no knowledge of significant figures.

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