Design and construction of 126m tall flagpole Design parameters 9

[Raja6]

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.

 

[Raja6]

Gentlemen I contacted NAAMM and they confirmed that NAAMM FP 1001 07 is the latest version. and it is not so convincing to note that this latest guide published in 2007 refers to only ASCE7 05 for wind load.

 

[Raja6]

JStephen
More than the aesthetics, the safety is very important. With flag if it deflects, the torsional forces from flag induced in the pole would add additional stresses.
So it is better to restrict the maximum deflection in the design i feel.

 

[Raja6]

Bridgesmith
Thanks so much for your very valuable sharing/casestudy.
For your information AASHTO has recently released their 41st edition in the market. I will definitely refer.
Two things are important according to you(galloping effect and use of dampers as a solution)
Fatigue cracks to be taken care off in the design.

 

[Raja6]

Aesur,
I am trying to sort out the applicable codes and standards and their latest versions to avoid mixing of basic requirements and provisions.
Thanks so much for your valuable suggestions.

 

[BridgeSmith]

For your information AASHTO has recently released their 41st edition in the market.

I'm not sure what spec you're referring to here. I have the 1st Edition of the LRFD sign spec with interim updates through 2022, and the 6th Edition Standard Sign spec, released in 2013 with interims through 2015, which as far as I know is the last time that one was updated. Of particular interest for your project would be the 2017 Interim revisions to the LRFD spec, which incorporate the results of a considerable amount of research regarding fatigue resistance of the typically-used welded connections for base-plate to pole connections, as well as fatigue resistance of other details. So, you should make sure you look at one that is at least updated with that 2017 interim.

I don't know of a 41st edition of any specs from AASHTO.

 

[Raja6]

Bridge Smith,
Thanks so much.
Yes you are correct. Typo. It is not 41st edition. It is 6th Edition with interim revisions.
Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals, 6th Edition, with 2015, 2019, 2020, and 2022 Interim Revisions.

 

[Raja6]

azcats,
I am looking forward to receiving your valuable input. Thanks.

 

[BridgeSmith]

It doesn't look like there have been any substantial changes to the fatigue section of the AASHTO Standard sign spec since 2015. The last changes to the fatigue section of the LRFD sign spec were in 2017, so it may be a bit different.

 

[LittleInch]

"I am reviewing on behalf of the owner the EPC contractor's design. I am doing the peer review"

With all due respect, this task did not look like you should be doing it. Owners Engineer / peer review is supposed to be by people and companies with significant expertise and experience in the particular field, yet here you are asking a bunch of Internet strangers detailed technical issues and even which codes to use??

Something doesn't sit right here with me I'm afraid.

Care to explain further?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Raja6]

Little Inch,
Thanks so much for your input.
I have already received the information I was looking for from this forum and from other forums.
Thanks somuch.

 

[Clerical Forensics]

Gentlemen I contacted NAAMM and they confirmed that NAAMM FP 1001 07 is the latest version.

This is interesting. I found this discussion because I was searching for FP 1001-18. The 2021 IBC references FP 1001-18 (Ch. 35). I thought maybe it was a typo since the newest version on NAAMM's site is 1000-07. The 2024 IBC also lists 1001-18.

I am curious if the current wind speed should be used as 1001-07 references AISC 7-05... which is just a little bit old now.

 

[Raja6]

Clerical Forensics
Please note that in ASCE7-16 and ASCE7-22, FP 1001-13 is referenced(see copy attached).
The basic wind speed map available in FP 1001-07 is reproduced from ASCE7-05.
ASCE7-05 uses importance factors I (see table 6-1) for wind loads for category I, II,III and IV as 0.87 or 0.77,1,1.15 and 1.15 respectively(depending upon the V value).
So you need to enhance the wind loads given in this map to suit your flag pole geographical location.
See equation 1 and 1m given in FP 1001-07
You may also note that FP 1001-07 uses only ASD method, but considers flag loads. All the best.

 

[BAretired]

Find out all you can about Vortex Shedding, because it is sure to be a major factor in the your design. It is often mitigated using strakes as illustrated below.

 

[JStructsteel]

Would windmill design be similar, or good references?

 

[BAretired]

Here's another strake. This one is in the form of a helix.

 

[Clerical Forensics]

Please note that in ASCE7-16 and ASCE7-22, FP 1001-13 is referenced

Were you, or has anyone, found a copy of the FP 1001-13? I inquired with NAAMM and just received an email stating that 2007 is the most recently published version.

 

[Raja6]

BAretired,
Thanks for your input. Yes you are right. Vortex shedding phenomenon is important in the design of flagpoles. It can take place even in the wind speed between 15 to 60 km/hour. Strake may be one of the mitigation measures. But the provision of dampers at appropriate heights of the flagpole can also mitigate vortex shedding. We need to also perform fatigue analysis and ensure that the threshold stresses are with in the limits specified and defined in ANSI/AISC 360 Specification for Structural Steel Buildings. see the attached brochure for more details.
All the best.

 

[Raja6]

JStructsteel,

https://en.wikipedia.org/wiki/IEC_6... international,(IEC) regarding wind turbines.

The above link might be useful.
Take care.

 

[Raja6]

Clerical Forensics,
I also received the same reply from them. It seems that FP 1001 07 is the latest one.
All the best.

 

[LittleInch]

You don't find strakes on flag poles as they tend to be a tapered design especially at that size or incorporate other anto vortex mitigations.

And they look terrible.

OK for a chimney, not OK for a flag pole.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.