AISC Appedix 3
AISC Appedix 3
(OP)
I had a question about equation A-3-1 in AISC Appendix 3. The formula uses a value of nSR, which is defined as number of stress range fluctuations in design life. Is this the total number of cycles that occur on the bridge over all stress ranges and its design life? Or is it the number of cycles that occur at the stress range Fsr. I am just a little confused.
I can provide the data I am looking at if need be.
Thanks for your time!!
I can provide the data I am looking at if need be.
Thanks for your time!!






RE: AISC Appedix 3
So, in my view, not ALL numbers of cycles corresponding to ALL ranges of stress enter nSR. As for checks only concomitant actions need be checked, in fatigue, only the number of times a given level of stress is ranged is counted (or one equivalent number if you integrate the effects for that).
RE: AISC Appedix 3
rantes in 2nd line is ranges
3d line suppress after 500 times "at the support"
RE: AISC Appedix 3
Example:
You check tension on a flange of a bridge beam. Say the beam experiences 2000 loadings per day of vehicles....i.e. 2000 times per day the flange goes into tension above its static tension.
The life span of the bridge is assumed at 50 years.
The value of nSR would be 2000 x 365 x 50 = 36,500,000.
Now not all of those loadings will be the same - some small cars, heavier trucks, etc. But each load application that causes tension would be included in the number.
You then determine FSR from the equation and then design a beam flange to have stress lower than that prescribed amount.
RE: AISC Appedix 3
RE: AISC Appedix 3
Thanks so much for your help!
I was hoping you guys could help me with another aspect of fatigue....the fatigue categories specified by AISC. I trying to find the detail shown by the attached picture I guess I am torn between category D and E. This is mainly because I am not 100% certain on what defines a pin plate.
Also it should be noted that the connections in the picture are riveted.