Tapered Plate Design Help

[Shaylon]

Hello,

My name is Shaylon and I am new to this site. I have been given the task to design the beam elements for an outdoor canopy. I am running into great difficulty in doing so because the members are to be tapered plates designed as thin as possible with as large and as many holes as possible while remaining structurally sound. I am fresh out of college and I am trying to build a knowledge base as to where to go with questions and guidance so I am turning to you guys. From the threads and postings I have read, there is a great deal of knowledge here and I am hoping that someone can help me out and point me in the right direction.

At the deep end, the plates are to be 33.668" and are to taper down to 3.5". Please see the attached file for further requirements, plate geometry, and canopy layout. Any and all help would be greatly appreciated. Thanks.

Shaylon

 

[ishvaaag]

Make a plate(s) or 3D model, include initial imperfections, account for material nonlinearity and P-Delta. Use FEM element that accounts for shear. Verify you remain within small deformation theory and limit deformation at service level, and limit strength.

 

[IFRs]

I can't help you. There is too much at risk and too many issues. You are in desperate need of a mentor, an experienced engineer who can guide you so you don't blunder and hurt someone. FEA might help, hand calcs with simplifying assumptions can work. In any case, good engineering judgment will be needed. Good luck my friend, do your best and try to at least get it reviewed by a qualified engineer.

 

[BAretired]

Looks like trouble, Shaylon. A thin plate tapered as shown will simply buckle under load unless you provide a bottom flange or other means of providing lateral bracing to the compression edge of the plate.

BA

 

[dhengr]

If Arch’s. got paid for crazy, they would all be rich. And, if they paid Structural Engineers fairly to shoulder the risk that the Arch’s design egos bring to a project we would all be richer. You probably will have to come up with some compression flange bracing system which adds architectural sex appeal to the system. That oversized mushroom thing is going to leak like a sieve at every structural member and glass panel joint. And, how are you going to drain this thing if it doesn’t leak? I would run a tension rod from the tip of each rib or fin up to a saddle on the top of the mast. Provide a turnbuckle on each tension rod. Watch out for wind loads on this inverted umbrella, and for any uneven loadings.

 

[ToadJones]

Why is the central column shown on an angle?
Is the central mast somehow not plumb?

I am having a hard time picturing this thing.
Is it only comprised of a single central column and a bunch radially projecting "fins"?

 

[Shaylon]

ToadJones,

Attached is a cross section of the canopy. The holes in the vertical plate members was a requirement noted in an email from the arch. and they do not show up on his section. This is a better overall picture of what he has in mind for this canopy.

For the loading, I have considered a balanced snow load acting on the whole area and an unbalanced load where the lower portion (from the column to the low edge) gets the full snow load while the upper portion (from the column to the high edge) gets only half of the snow load.

 

[ToadJones]

I'd see if the Arch will go for Castellated Wide Flange beams....give it a nice 1960's look.