CJP alternatives - FW+PJP

[SM3225]

It is common knowledge that maximum practical fillet weld size is ½” (13mm) – common practice to employ another type of weld, such as groove weld, when the calculated weld is greater than ½”(13 mm).
Typically CJP welds are the most expensive weld and I feel the same should be reserved for situations in which they are the only viable option.
Coming to the original problem – this is the weld between shear lugs and base plate. In the current case, type of shear plate employed is Cross Plate Shear Lug - owing to the existence of pretty high magnitude of forces, plate thickness is worked out as 1-1/2”(40 mm) – first pass shear plate dimensions 6”(150 mm)longx8”(200 mm) deepx1-1/2” (40mm) thick.
Consideration of Fillet weld (FW) alone requires a fillet leg size of approximately 1-1/8” (28 mm) – what would be the probable combination of FW+PJP instead of a CJP one.
I am planning to employ a FW(1/2”or13 mm) + PJP(1/2” or 13 mm).

How to arrive at a calculation which possibly demonstrates design strength (fRn) of FW+PJP is more than the required strength (Ru)? I am planning to carry on as mentioned below
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Equate the kips/in (N/mm) of a 1-1/8” (28 mm) FW = kips/in (N/mm) of FW(1/2”or 13 mm) + PJP(1/2” or 13 mm) – more precisely setting the FW leg size to ½”(13mm) – we’d only be left with the finalization of PJP size.

Does anyone have similar experience earlier – please let me have your opinion.

Thanks & Regards.

 

[Lomarandil]

If you don't need a CJP for the joint preparation or QC (or maybe fatigue properties) that come along with those welds, great! I absolutely agree -- don't overspecify.

But I'd tend to just call out a PJP of the appropriate size. If a fabricator feels that a PJP backed with a fillet is more economical, they can offer that alternative.

Depending on the scale of fabrication and where your fabricator is located, my experience is that PJP alone may be cheaper. Let them decide.


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The name is a long story -- just call me Lo.

 

[MGZmechanical]

In the european code if you don't have fatigue or traction action a PJP+FW is equivalent to a CJP as far as:
c <= t/5 or 3 mm (see drawing attached)

 

[SM3225]

Lomarandil & ManoloGalarraga - thanks to both of you for quick response.