structural steel platforms: the fiddly bits
structural steel platforms: the fiddly bits
(OP)
Hi guys. I have my grasshopper hat on again today.
I am designing a small extension to an existing maintenance platform. The loads are minimal and the primary members are ample so I am tempted to use minimal diagonal braces below the platform. My problem is that normally I would not attribute any bending strength to simple shear connections. My question is whether this can be done when the loads are negligible and whether bolted shear connections will snug up and be serviceable for small cantilever areas without considering typical moment connections or diagonal braces at each end of each remote member.
I am designing a small extension to an existing maintenance platform. The loads are minimal and the primary members are ample so I am tempted to use minimal diagonal braces below the platform. My problem is that normally I would not attribute any bending strength to simple shear connections. My question is whether this can be done when the loads are negligible and whether bolted shear connections will snug up and be serviceable for small cantilever areas without considering typical moment connections or diagonal braces at each end of each remote member.






RE: structural steel platforms: the fiddly bits
RE: structural steel platforms: the fiddly bits
As a second note, it may be worth field welding the angles to the plates, it is stiffer and will just button it all up nicely. I'd weld it.
As a third note, we typically use two (2) angles for our base of rail details as this is a more uniform loading situation, yes it is overkill but it looks cleaner than the single
And the fourth... If you do not have much force going to those kickers and 3BR3 then why have 8 bolted gusset-to-column connection?
RE: structural steel platforms: the fiddly bits
What’s a grasshopper hat? In my old age I’m missing half of the new age vernacular, these days.
Damn near every connection we design has much more cap’y, in every direction, than we give it credit for, all for simplicity of analysis, design, detailing. Doesn’t the connection of the grating offer another level of redundancy or another energy absorbing layer of structure, in the lateral direction? What are the chances of all of these load conditions happening at the same time? We have gotten so damn chicken shit about doing anything that we know is inherently adequate, except in the most extreme situations, if it is not explicitly covered by a code paragraph. We are literally relinquishing our authority as the experts on these matters to the tech writers or the democratically selected code writers, what the hell do they know? Look at thread507-363503: Hillside washers, and put in a couple of diag. rods if you are really in doubt about the lateral cap’y of your design.
RE: structural steel platforms: the fiddly bits
oh no. grasshopper is old school. some days the master i am. some days the grasshopper. ahhh sooo.
RE: structural steel platforms: the fiddly bits
When I was doing refinery design, I learned to try for an element of redundancy with this type of situation because the pipers and sparkies tended to cut holes in, and hang stuff from these platforms.
Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin
RE: structural steel platforms: the fiddly bits
RE: structural steel platforms: the fiddly bits
Or maybe they'll just put the truck on the platform.
Don't bet that it can't be done.
Mike Halloran
Pembroke Pines, FL, USA
RE: structural steel platforms: the fiddly bits
Honestly, I'm more worried about torsion, regardless of how you connect. You could have strength/deflection issues on the existing members. You also have to look at how those existing members are connected to other beams and their supports. Throwing torsion into structures where it wasn't expected can get messy, even with loads that otherwise look really small.
It looks like a little bit of rearrangement could give you enough support that you don't need to rely on torsion. See attached.
RE: structural steel platforms: the fiddly bits
Dik
RE: structural steel platforms: the fiddly bits
Torsion issues and section stability aside, my main question was a general one and it sounds like the consensus is that some calculated moment can be transferred through simple shear connections by doing a T/C calculation on the bolts through the web. Normally in moment connections the entire moment is designed to go through the flanges.
Thanks again all.
RE: structural steel platforms: the fiddly bits
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