Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Fatigue design

[Subject Prev][Subject Next][Thread Prev][Thread Next]
I'm looking at an amusement type structure, with over 2 million load cycles.
Hmm, fatigue design, not my strong suit.

Salmon & Johnson textbook (2nd edition page 61) refers to a Modified Goodman
diagram.  It seems like the point is if you have less than full stress
reversal (R = -1), you are allowed a higher maximum stress.  Are you also
allowed a higher stress range?

AISC Appendix K Fatigue design (ASD design), it seems like it is
conservatively set up for full stress reversal R = -1 only.  Is this true?  
If you have low stresses in full reversal (R = -1), seems like you are
better off than with full stresses in full reversal. Is this true? 
If so, how does AISC Appendix K account for this?  
How does AISC account for less than maximum stress reversals (R = +1/2, 0,
-1/2 etc. etc.)?

Based on a quick reading, it seems like the European fatigue standards (DIN
15018 for cranes) are a little better than AISC standards in acknowledging
issues like quality of work, quality of materials, stress ratios etc.  Any
thoughts?

My instincts tell me if my typical dead + live load reversal stress range is
down at 3 to 4 ksi maximum (not 24 ksi), and then the maximum seismic or
wind hits the structure, that I could use higher values for maximum stress
and stress range with wind and seismic.  Is this true?

Thanks for any thoughts!

Steve Uthoff