1) I did not go through all of the calculations leading up to the weld calculations.
2) On one equation in section 1.4.1, your units are incorrect, but your numbers are correct. You state mm^4, where it should be mm^3. Not a big deal.
3) In the same section under "Load Due to Moment," you use a depth of 219mm, which is smaller than the 259.6mm which is the overall depth of your weld group.
4) In the next section, you refer to a fillet weld. Just be sure that you can use your 1.6 design factor that you are talking about using here. I do not know where you got 1.2kN/mm for an 8mm weld (which may be fine -- I just don't know), but make sure that this value is acceptable for applying shear through the throat of a fillet weld, since loading your fillet in shear is different from tensile loading in PJP and CJP welds.
5) I may have forgotten some of my book learning, but I don't have any idea what is going on in section 1.4.2. I don't know how we would get F=M/(weld depth). I could be missing something here, but I'm not sure what this section is about.
6) Is there any consideration for seismic activity?
7) Will the structure have to deal with dynamic loading due to high flow rates of the fluid in the pipes and the piping elbows which would impart those loads?
8) Will expansion/contraction of the length of the pipes due to heating/cooling cause a displacement which could buckle your columns?
The weld calculation for the one weld analyzed looks like it's probably ok.
HOWEVER:
Just because your weld is strong enough DOES NOT MEAN that the way you have joined the beams is appropriate. A properly-designed moment connection between two I-beams requires more than simply welding the end of one beam to the flange of another. It is almost assured that you will need gusset plates to join the flanges of one beam to the flanges of another so that the moments can be transferred from one beam to the next at the structural knee.
The design of these knees can be found by buying a few books at this link:
MANDATORY PURCHASES:
1) "Design of Welded Structures"
2) "Solutions to Design of Weldments"
HIGHLY RECOMMENDED PURCHASES:
1) "Procedure Hanbook"
2) "Metals and How to Weld Them"
The books are sold at a ridiculously cheap subsidized rate. You won't find any technical books this cheap with this much valuable information in them anywhere.
Good luck.
Engineering is not the science behind building. It is the science behind not building.
