Wind Uplift 2

[whyun]

What is the method of calculating an uplift capacity of a single 1/2" or 3/4" puddle weld from a metal deck to a steel members subject to a net uplift force due to wind.

Say calculated wind uplift is 40 psf, DL on the deck is 15 psf, deck is 20 ga B-Deck (1 1/2&quot, welds are at 12"oc at the supports, typical beam spacing is 8'-0" oc. Net uplift to resist would be 40 - 15 or 25 psf.

Connection will be not be a problem by inspection but for a rigorous check what would we do? Thanks for the advice.

 

[Lutfi]

Go to this link. It has PDF file that has the data that you will need.

Just a small note, make sure you apply the wind load for components and cladding with the proper area. Also, I would not deduct too much dead load. This is conservative. Welders do not always do a nice job with puddle welds.

 

[JAE]

I've got an older version of the AISI manual (1989)
and it offers the following:

Nominal tension load Pn on each arc spot weld between sheet and supporting member shall not exceed:

Pn = 0.7 x t x da x Fu

Where:
da = average diameter of the weld at mid-thickness of t (da = d - t) with d = visible diameter of the weld and t = total thickness of your gage plate.

Fu = ultimate stress of your gage plate

They specify that the following limitations apply:

e(min) >= d
where e = Force / (Fu x t)

The electrode is >= 60ksi

That Fu <= 60 ksi

That t >= 0.028 inches.

Keep in mind this is a bit dated (1989)

 

[Lutfi]

her is the link..

http://www.njb-united.com/usd/ddds/data18r.pdf

 

[whyun]

Thank you both.

Using JAE's equation, I get the following:

Pu = 0.7 x 0.0359 x (0.75-0.0359) x 45 ksi = 0.807 k

Using Lutfi's chart, I get 1710 # (Figure 1, 0.75&quot; puddle weld, A653G33, 20 ga.)

Any idea why the difference? Table is Tensile &quot;Strength&quot; and indicates Omega of 2.5. Thus allowable should be 1710#/2.5 = 684#. This is much closer to results from AISI.

Am I interpreting this correctly?

Regards.

 

[Lutfi]

For quick calculations, I normally use the chart data with the 2.5 safety factor. The results are more conservative. The table is NOT based on AISI 1996 manual which may explain the delta in the values. Without doing more detailed investigation, that is all I can offer at the moment.