# Tension Member



## MOOK (Mar 12, 2009)

This question regarding design of Tension members

In case of double angle back to back tension member with 3 or more bolts. We need to determine the effective area Ae

Ae= u * An

The factor u = 1 - xbar/L OR

u for double angle can be treated as single angle and we can determine it from Table D3.1 AISC.

Some references use the first method and the others use the second method.

Does anyone know what is the correct method for double angle case?

Thanks


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## RIP - VTEnviro (Mar 13, 2009)

> This question regarding design of Tension members


You might want to check with PE-ness on this one. He's pretty much the board expert on members in tension.


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## BLMedcalf (Mar 13, 2009)

You should use the 1-xbar/L, with xbar being the distance from the back of the angle (in contact with the gusset) to the angle CG.

This is how I have always designed angle connections. I think the single angle parameters you cited are a simplified approach that is used in lieu of the method I just described.

I hope that helps.


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## RIP - VTEnviro (Mar 13, 2009)

I still would rather hear what PE-ness had to say about the matter.


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## MOOK (Mar 13, 2009)

VTEnviro said:


> I still would rather hear what PE-ness had to say about the matter.


What do u mean by PE-ness??


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## MOOK (Mar 15, 2009)

BLMedcalf said:


> You should use the 1-xbar/L, with xbar being the distance from the back of the angle (in contact with the gusset) to the angle CG.
> This is how I have always designed angle connections. I think the single angle parameters you cited are a simplified approach that is used in lieu of the method I just described.
> 
> I hope that helps.


Actually, it is not simplified approach. If you use 1-xbar/L, you will get u= 0.9 but if you follow Table D3.1 case 8 (3 fastner) you will get u=0.6 which is completely different answer.


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