Pole Fatigue Calc for Key West: AASHTO Spec & Vc of 45mph

In summary: The AASHTO standard specifies units of pounds per square foot, while the units you are using in your spreadsheet might be kilograms per square meter. If you are using units that are not consistent, this will affect the results of your calculations.
  • #1
Fat Ryan
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I was asked by the CE to do a fatigue calc for a speaker pole going up in key west. I am using AASHTO standard spec for structural supports for highway signs, luminaires, and traffic signals. he said to assume a Vc of 45mph, an importance factor of 1.0 (from category I-lights in the cantilevered section) to be conservative. he also said to use the detail category E' for the CAFL, which results in a CAFL of 2.6ksi. all the specs from the pole and speaker set are from another spreadsheet we have here. its a 50' 16-sided tapered steel pole. to give you an idea, the diameter ranges from 21.2 to 14.2 inches with an X-section area ranging from 16.5 to 11 in^2. the speakers mount atop the pole and weigh in at 440lbs.

ive attached my spreadsheet with the calc. I've never done a fatigure calc and this AASHTO spec is god awful at explaining what to do. I am getting a required loads that are like 50,000 times higher than the CALF lol. I am guessing the "conservative" 45mph wind speed would play a large role considering its squared in the pressure equation. and the drag coefficient i have for the speaker seems awfully high. but i also don't really even know what I am doing in the first place. I am assuming the critical section is at the poles base (by the fillet weld to the base plate). It seems that'd likely be where fatigue cracks would form in my mind.

so am i doing something wrong here? perhaps I am missing some key theory...
 

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  • Copy of 50H Fatigue calculation.xls
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  • #2
One thing you are doing wrong, self weight is a static load and cannot induce fatigue damage.

It is not possible to verify the equations in your spreadsheet, but you might be working with the wrong units.
 
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1. What is Pole Fatigue Calc for Key West?

Pole Fatigue Calc for Key West is a tool used by engineers and transportation professionals to calculate the structural fatigue of utility poles in the Key West area. It takes into account the AASHTO (American Association of State Highway and Transportation Officials) specifications and the wind speed limit of 45mph in Key West.

2. How does Pole Fatigue Calc for Key West work?

This tool uses mathematical equations and algorithms to analyze the structural properties of utility poles in Key West. It takes into account factors such as wind speed, pole material, and design specifications to determine the fatigue life of the poles.

3. Why is Pole Fatigue Calc for Key West important?

Pole fatigue is a serious concern for utility companies and transportation agencies, as it can lead to pole failures and disruptions in service. By using this tool, engineers and professionals can accurately assess the fatigue life of utility poles and plan for maintenance or replacement accordingly.

4. Is Pole Fatigue Calc for Key West accurate?

Yes, this tool is based on the AASHTO specifications and has been validated through extensive testing and research. However, it is important to note that it is only a tool and should be used in conjunction with other engineering practices and considerations.

5. How can I access Pole Fatigue Calc for Key West?

This tool is typically available as a software program or online tool, and can be purchased or accessed through engineering organizations or transportation agencies. It may also be available for use through academic institutions or through consulting firms that specialize in transportation engineering.

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