Tall Lightning tower column attached to the piperack

[allimuthug]

Hi,
I have a two level pipe rack, First level supporting pipe is at the elevation of 2.5 m above Grade. Second level supporting cable tray is at elevation of 5m above grade. The pipe rack is subjected to thermal seismic and all other kinds of loads.
Unfortunately a column in piperack is extended 20 m above the grade to support a lighting point.
How I would design the extended column over the pipe rack please explain me.

Please not it is a steel pipe rack

 

[MotorCity]

No need for a lightning rod, just run a grounding rod 10' into the soil with a copper wire attached to the base of a column. If your structure is exposed steel, the whole thing is a lightning rod.

If you still want to do it your way, just design it as a cantilever pole and apply wind load.

 

[Ingenuity]

lightning rod

MC - the OP said 'lighting' - as in illumination - NOT lightning

 

[MotorCity]

Title of the thread says "Lightning"......guess we need the OP to clarify

 

[dhengr]

Allimuthug:
Actually, your sketch appears to show a fairly good design situation for the 66' high light pole. It is cantilevered from grade, and up about 16' (the back span) to the canti. reaction point, at the second level, and then up to the lighting system at 66'. The tall pole is supported in two orthogonal directions by the pipe rack and its bracing system. If this is a new design, then you design that corner column/pole and the rack bracing in the immediate area accordingly. If this light pole is to be added to the top of an existing pipe rack, you will probably (most likely) have to reinforce the existing corner column and the bracing in that area for the new loads. The canti. base fixity will be a significant design consideration. You could also add some diagonal braces from the top of the second level, maybe the top of the adjacent columns in the outside frame lines, in those two planes, to the 20 or 25' elev. on the new light pole.

 

[dik]

I'm not sure your mast has to be so high unless it's needed to protect other items. Should have an air terminal or lightning rod at the top and properly grounded. See the attached.

 

[allimuthug]

Can there be cyclic loading on the column due to continuous wind load and Vortex shedding.
Else there could be torsion in the column since the wind can act any direction.
I have to prove that this may work or not by proper calculation. Please share your opinion.

 

[dhengr]

Allimuthug:
Yes, yes, and get out your calculator and start provin. I would think it can be made to work.

With questions like you’re asking, you might want to find a local Structural Engineer to help you with this. You can give him all the details he needs to do the analysis and design, and he can keep you advised of what the is doing, and how and why. You have really provided no meaningful info. here, so far, and we are not in the business of doing people’s design work for them.

 

[thaidavid40]

Since the column extends so high, and can take on wind and/or seismic moments in both directions, using a rectangular HSS section might make better use of the member's strength properties.
Dave

Thaidavid