Aspect Ratio of Small Tower
Aspect Ratio of Small Tower
(OP)
I am designing a small, 4 legged, open structure with braced frames on 4 sides to support a couple of industrial platforms, 45 feet in height. No significant dead load other than the steel weight. Wind will be limited because it is relatively open.
I am looking for suggestions on a starting point for the distance between legs. I have my own ideas, but want to see what you guys think.
I am looking for suggestions on a starting point for the distance between legs. I have my own ideas, but want to see what you guys think.






RE: Aspect Ratio of Small Tower
RE: Aspect Ratio of Small Tower
DaveAtkins
RE: Aspect Ratio of Small Tower
I was thinking more of an aspect ratio of 6:1 which gives about a 7'-6" base.
The piece of equipment that we are accessing has a similar aspect ratio (although more DL and more WL) and I don't want the platform structure to look out of place.
I guess it has more to do with "looking right" than engineering.
RE: Aspect Ratio of Small Tower
Your aspect ratio will depend upon your panel height. Panel ht. and bottom width will influence your bracing angle( depending upon X or K type bracing you may have). Try to keep the angle between 30-55 degrees to avoid fabrication and erection problems.
Also keep in mind the requirement of ladder slope. EIA/TIA-G and CSA S-37 will not allow too steep slope for safety reasons.
LOKSTR
RE: Aspect Ratio of Small Tower
I agree with you. 7'-6" seems just fine for a starting point. I would assume that the overall size of the structure will be governed by the platform geometry and then the members will be sized for the wind and D.L.
RE: Aspect Ratio of Small Tower
RE: Aspect Ratio of Small Tower
RE: Aspect Ratio of Small Tower
Make sure to actually calc the open area as many times trussed structures are not as open as you think as far as code is concerned.
RE: Aspect Ratio of Small Tower
ASCE 7 gives force coefficients too for trussed towers, so that may also help determine size and bracing requirements.
RE: Aspect Ratio of Small Tower