Fatigue Cycles for Wind Loading

[ToadJones]

Anyone aware of any literature on determining the number of cycles for fatigue wind loading?

 

[rb1957]

i guess you've got info about wind gust speeds for your location ? 1/100 years, 1/1 year, ... ?

i assume you can't design to the endurance limit (ie assume an infinite number of gusts) ?

 

[bridgebuster]

The AASHTO luminaire manual gives fatigu stress limits for various details but it doesn't get into cycles.

 

[WillisV]

Fatigue generally isn't an issue w wind loading on typical structures.

 

[ToadJones]

I guess I dont consider what I am working on to be "Typical"

http://www.eng-tips.com/viewthread.cfm?qid=329809

 

[dhengr]

That is definitely not “Typical,” Toad. Use 27 billion cycles to be on the safe side.

 

[msquared48]

Especially considering the effect offlutter on single column sign posts...

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[JAE]

There have been significant failures in some large bill board signs (think large diameter steel pipe with extended frame above for the billboard).

The sign starts oscillating and eventually fatigue cracking kicked in and the car dealership advertisement was no more.

 

[ToadJones]

not sure why that link appeared in my last post...

dhengr-
usually you drive me stinking nuts with your long winded useless rants on here that denigrate anyone who doesn't post a to-scale sketch, all design parameters, materials, loads, load paths, bracing schemes, layouts, meeting notes, seismic design criteria, a copy of their bachelors degree verifying their acceptance int he structural community, height, weight, waist, shoe and hat size, dress codes for their design office, power point presentations describing the question, design drawings, CAD details, column schedules, window schedules, door schedules, project schedules, ABET accreditation for their univeristy, Anchor bolts plans, steel plans, elevations, all architectural details, partition loads and in fact, the answer to the question in the OP, but I got a good laugh out your last comment.

 

[paddingtongreen]

AISC used to be specific that wind does not cause fatigue. That did not cover cases such as vortex shedding because there is little likelihood of a constant wind over the life of the pole.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[Ron]

TJ....search for aolian structural vibrations. You'll get some info on wind oscillation of structures. One thing to keep in mind is that the stress effects of vibration are cumulative across the vibration spectrum, which makes correlation to S-N curves a challenge!

 

[rb1957]

alot of posts talking about signs ... Toad, are we talking about a sign ?? what makes your structure "not typical" ?

 

[ToadJones]

It's a canopy structure with some mechanical equipment connections that could be sensitive to fatigue loading from wind or vibration.