Fillet Weld Strength 1

[STEVE97]

I have always known that the allowable shear stress of a fillet weld to be based on its effective throat thickness and the allowable stress equal to (.707)(.30)(70). Is this the same when the weld is loaded perp. to the longitudinal axis of the weld and is it is in tension?

 

[kslee1000]

When you have such a case, shouldn't you use butt weld or other full penetration welds rather than designate fillet weld, which I don't see how could it be.

 

[nutte]

The weld is 50% stronger when loaded perpendicular to its longitudinal axis. You still have shear on the effective throat.

 

[STEVE97]

Nutte,

Where can I find this written? Is it in the ASD manual?

 

[msquared48]

You might try looking in Blodgett...

Mike McCann
MMC Engineering

 

[nutte]

It's not in the green ASD manual. It is a "new" development since that manual was released.

Look at equation J2-5 on page 16.1-100 in the 13th black manual. It's the term with the sin theta in it that gives you 1.5 when perpendicular.

It's in the 3rd LRFD manual on page 16.1-115.

It first appeared in the 2nd LRFD manual.

 

[STEVE97]

Thanks Nutte!!!! I am so used to the 9th Edition that I am still getting used to the 13th. So let me get this straight based on a 1/4" fillet:

theta = 90 degrees

Aw = .707(1/4)=.1768in

so: Fw = .60(70ksi)(1.5)=63ksi

Rn = (63ksi)(.1768in) = 11.14k/in

11.14 k/in / 2 = 5.56 k/in allowable

Parrallel to Axis = (.707)(70)(.30)(1/4) = 3.71 k/in

5.56 k/in / 3.71 k/in = 1.5

Thanks Nutte, makes sense now. That was a big help

 

[msquared48]

For E70 electrodes, I always have figured 900# per 1/6" of weld, per inch of weld, or about 3600# per inch with a 1/4" weld. (Parallel to axis)

For E60, use 2/3 of that.

Mike McCann
MMC Engineering

 

[youngstructural]

I think it's newish to the AISC code, but has been known through testing for near on 100 years. The AISC Design Guide 21 discusses this.

Regards,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...