Converting Double Channel Plate to Rectangular Hollow Section
Converting Double Channel Plate to Rectangular Hollow Section
(OP)
Hi all,
I have a problem. I have proposed the Steel RHS for the mullion but the client said it is too expensive. So, they want to change the section from combining the channel section. They said it's cheaper.
Do you guys have any thoughts of this? Does this section is possible to build?
Hereby I attached the drawing of the section.
Thanks in advance
I have a problem. I have proposed the Steel RHS for the mullion but the client said it is too expensive. So, they want to change the section from combining the channel section. They said it's cheaper.
Do you guys have any thoughts of this? Does this section is possible to build?
Hereby I attached the drawing of the section.
Thanks in advance
Pratama H.R.S., B.Sc, M.Sc
Facade Engineer






RE: Converting Double Channel Plate to Rectangular Hollow Section
RE: Converting Double Channel Plate to Rectangular Hollow Section
Pratama H.R.S., B.Sc, M.Sc
Facade Engineer
RE: Converting Double Channel Plate to Rectangular Hollow Section
Channel sections (C & MC, in the states) have some taper to the flanges, so the tip of one flange will not line up nicely with the heel of the other flange, as you're showing.
Overall, I don't really like it, but can't quite quantify as to why. I suspect you feel the same or you wouldn't have posted here...
RE: Converting Double Channel Plate to Rectangular Hollow Section
RE: Converting Double Channel Plate to Rectangular Hollow Section
In terms of pure structural performance, this solution is better than the RHS. If the client prefers the double channel, I would certainly allow it. KootK approved.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Converting Double Channel Plate to Rectangular Hollow Section
Reminds me of the eccentric brace knee connection I worked on as a forensic engineer while in NZ; It was designed to be a pin connection, looked entirely reasonable, and caused structures to fail at a fraction of the required design load. https://www.building.govt.nz/building-code-complia... No one expected that, but it still happened.
Sometimes good engineering practice is doing our design with as little innovation as possible. But, somewhat ironically, I also like the alternative detail of the two PFCs nested into one another... I would just be likely to design this elastically, rather than allow plastic flow to initiate in an untested section.
RE: Converting Double Channel Plate to Rectangular Hollow Section
RE: Converting Double Channel Plate to Rectangular Hollow Section
RE: Converting Double Channel Plate to Rectangular Hollow Section
I agree with XR250 - The fabrication labor here will really add to the unit price of these things.
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RE: Converting Double Channel Plate to Rectangular Hollow Section
The wind load is 1 kPa. The width of the panel is 1350mm. I think it's a lighlt loaded since the uniform load is about 135 kg/m2.
The thing is fabricators in Indonesia don't produce much hollow section so hollow section become the unusual section to fabricate. Maybe they don't even have enough technology to produce it.
By the way, should I check the profile for 2 C's or just RHS is enough?
Thanks
Pratama H.R.S., B.Sc, M.Sc
Facade Engineer
RE: Converting Double Channel Plate to Rectangular Hollow Section
Given the way that structural mullion will fabricate and assemble, you might be better off if you made it up from one channel shape, on one side, and the other web (side) being a flat strip/sheet a bit wider than the channel is high. This will allow you to make both connecting welds down hand fillets from the same clamped assembly fixture position. Then rotate the fixture 90̊ and weld on one of the small trim attachment channel shapes to the main structural mullion flange, and rotate it again, 180̊, to weld the other small trim attachment channel shape to the main structural mullion. The above approach should improve fab. and assembly and present fewer fit-up problems. This approach might require that you use slightly thicker sheet material for the structural mullion portion, for both the formed channel and the flat strip/sheet web piece, to get the same section properties.
RE: Converting Double Channel Plate to Rectangular Hollow Section
RE: Converting Double Channel Plate to Rectangular Hollow Section
I would check it as an RHS with a constant wall thickness. If that didn't work, I would check it as an RHS with the additional flange material included and checked appropriately for local buckling. I wouldn't check it as two independent channels as lateral torsional bucking would likely not work for that condition unless one were to make the somewhat dubious assumption of continuous rotational restraint being provided by the glass, gaskets, and pressure cap assembly.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Converting Double Channel Plate to Rectangular Hollow Section
Dave
Thaidavid
RE: Converting Double Channel Plate to Rectangular Hollow Section
I don't really understand about the residual stress caused by continuous weld.
Can you explain the twist? Why will it happen if I do the continuous weld?
Can you please show this mechanism in the drawing or sketch? I'm a little bit confused. Sorry :(
Thanks
Pratama H.R.S., B.Sc, M.Sc
Facade Engineer
RE: Converting Double Channel Plate to Rectangular Hollow Section
RE: Converting Double Channel Plate to Rectangular Hollow Section
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