Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

Register Log in

Design and construction of 126m tall flagpole Design parameters 9

Status
Not open for further replies.
Raja6

Raja6

Structural
Aug 16, 2023
24
0
0
AE
Hello Gentlemen,
Recently I have been entrusted with the assignment of reviewing design and construction documents for a 400 ft tall flagpole.
I am looking for answers to the following questions:
1. (ANSI/NAAMM FP 1001 07 Guide specifications for design of flagpoles) Which is the latest version of this specification? 2007 or 2013?
2. The maximum height specified in this spec is 300 feet only. Which spec is applicable for heights beyond 300 feet?
3. ASCE7 is referred in this specification. Do we need to use the latest version of ASCE7 2016 or 2022? Which ASCE7 is compatible with this spec?
4. What is the reference for coating for the steel?
5. What should be the minimum design life?
6. What is the allowable deflection? H/50 or H/60 or less?
7. Is any other reference code or Guide specification available in the industry?
8. What is the Risk category applicable? I or II or III or IV? Is this structure considered as a monument or special structure?
Thanks for your input in advance.
 
Replies continue below

Recommended for you

Sort by date Sort by votes
The AASHTO LRFD Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals would have some basic design parameters; enough to give you the fatigue stress limits for different connection details.

The design approach used for large electrical transmission towers might get you closer to what you're designing.

The loading, however, is another matter. For something of that scale and complexity, there are anumber of aeroelastic phenomena that can only be quantified by scale model testing and analysis. We found that out the hard way. We followed the standard design approach for our 120' high mast light towers (HMLTs) and we've had a number of them develop fatigue cracks and a few snap and fall over. Luckily none of them fell on anyone or anything. There was a galloping effect that was unanticipated and created cyclic loading effects well beyond what we designed for.

You'll probably need to do as we did for our HMLTs, and employ a consultant who can do the advanced computer modeling and wind tunnel testing, to capture the effects of wind, rain, ice, etc. The firm we contracted with was able to recreate the galloping effect we observed, and was able to test our new configuration, and when it exhibited the same issue, they provided options for dampers. Then they were able to test the damper options we thought were feasible to implement. It was a long and expensive process to get to what we hope will be a durable pole.
 
Upvote 0 Downvote
There are some car dealerships around here with relatively big flags. I've noticed a few of those can have visible deflection in the wind. So one question: Is visible deflection and/or vibration acceptable even if the design criteria are met otherwise? If not, one step is to determine what that maximum deflection or vibration is from a cosmetic standpoint.
 
Upvote 0 Downvote
That is quite the list of questions, have you reached out to the local jurisdiction for guidance on the code version? The AHJ is the only ones who will know what version of code they have locally adopted.

It appears you may be newer to engineering? Do you have a mentor? With a structure such as this, there would be significantly more checks than just wind loading and weight. Wind itself could create a galloping effect on the pole, there may be vibration concerns, even the base connection could be quite challenging to design.

You say "reviewing design and construction documents" are you acting as the engineer, or checking another's work?

A few of your questions would need the owners input as well, ie life span, their allowable deflection tolerance, etc.

I assume you would need electrical and lighting in a structure this tall as well, have you considered how this will be routed, will there be access plates, how do they affect the strength of the member, etc.
 
Upvote 0 Downvote

and lightning, too maybe...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
Upvote 0 Downvote
That's a good reference, dik. I would presume that the recurrence interval would need to be higher than 50-years if there are any structures within 400 ft of this pole. Unlike a typical flagpole, this one could smash through just about anything it came down on, so it would be subject to a higher factor of safety.
 
Upvote 0 Downvote
dik I have this Guide with me... I want to know whether FP 1001 -07 is the latest or FP 1001 -13 is the latest because 13 is refereeed in both ASCE7 -16 as well as ASCE7-22
 
Upvote 0 Downvote
Little inch Thanks so much for your input. I am first timer to this forum. I already read this post which you had shared. Thanks for the link any way. Trident support is also a good link. Thanks again.
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

mte12
  • Question
Silo quaking in design of bins and suppport structure 1
Replies
6
Views
29
mte12
mte12
DC_Engr
  • Question
Lateral design of storage containers
Replies
2
Views
13
DC_Engr
DC_Engr
sjay123
  • Locked
  • Question
Boom Structural Analysis and Design 3
Replies
5
Views
9
ChorasDen
ChorasDen
Talop
  • Question
Design Beam and Column with Overstrength
Replies
5
Views
10
Talop
Talop
Ben29
  • Locked
  • Question
Tall Parapet 1
Replies
12
Views
16
XR250
XR250
Back
Top