aluminum slenderness limits
aluminum slenderness limits
(OP)
I wrote here yesterday and I'm afraid I didn't phrase my problem very well.
I am useing the 2000 edition of the aluminum design manual (allowable stress method).
In section 3.4.14 I am having trouble calculating S1.
I am useing equation 3.4.14-4 and useing the buckling constants from table 2-1 and Fcy=16ksi(my aluminum is 6063-T5 <.50)my result is 127.345....now I compare that to the value in design guide Table 2-22 and here the limiting value S1 is given as 204.
If I multiply my result by 1.6 S1 would round to 204 but I am not sure that this is correct. It doesn't seem like it would be since my value for S2 useing equation 3.4.14-5 seems to round to the expected number of 3830 without any additional use of a saftey factor.
Thanks for any help in this matter.
I am useing the 2000 edition of the aluminum design manual (allowable stress method).
In section 3.4.14 I am having trouble calculating S1.
I am useing equation 3.4.14-4 and useing the buckling constants from table 2-1 and Fcy=16ksi(my aluminum is 6063-T5 <.50)my result is 127.345....now I compare that to the value in design guide Table 2-22 and here the limiting value S1 is given as 204.
If I multiply my result by 1.6 S1 would round to 204 but I am not sure that this is correct. It doesn't seem like it would be since my value for S2 useing equation 3.4.14-5 seems to round to the expected number of 3830 without any additional use of a saftey factor.
Thanks for any help in this matter.






RE: aluminum slenderness limits
It states that in the Tables the Slenderness Limits are calculated based on the intersection of the expresseions given in Table 2-2 for allowable stress for slenderness less than S1 and allowable stress for slenderness between S1 and S2.
In your example:
Find the intersection as
9.5=10.5-0.070(x)^0.5
solving for x, gives x=204.
Also mentions not to be alarmed by such a difference (127 compared to 204) since when allowable stress are calculated the differences are small.
10.5 - 0.070*(127)^0.5 = 9.7 ksi
10.5 - 0.070*(204)^0.5 = 9.5 ksi
Hope this helps. This book is very helpful if you do a lot of aluminum design.
RE: aluminum slenderness limits