I found an NDS problem (...sort of)! It is from Lindeburg Practice Problems book... although it is under the structural section, but nonetheless here it goes:
Problem 45.3 (11th ed)
A 4in x 4 in (nominal size) timber post is used to support a sign. The post's modulus of elasticity is 1.5x10^6 lbf/in^2. One end of the post is embedded in a deep concrete base. The other end supports a sign 9 ft above the ground. Neglect torsion and wind effects. What is the Euler load sign weight that will cause failure by buckling?
a- 2700 lbf
b- 3700lbf
c- 4000lbf
d- 5500lbf
Answer:
1) I = bh^3/12= (3.5)(3.5^3)/12= 12.51 in^4 (finished lumber size)
2) k = (I/A) ^ 1/2
k= (12.51/(3.5"x 3.5"))^1/2= 1.01 inches
3) The end restraint coefficient is C= 2.1 (NDS) <--- this line is quoted directly from Lindeburg's problem book. Does anyone know where to find this C=2.1 figure in NDS? (I obviously don't know how to use this reference) Any body have any pointers???
4) The slenderness ratio is:
L'/k= CL/k= (2.1)(9'x12)/1.01 = 224.6
There is note here: L/k is well above 100. (Note that most timber codes limit L/k to 50, so this would not be a permitted application).
5) Fe= (pi)^2 E I/ (L^2) = [(pi^2) (1.5 x 10^6 lbf/in^2) ( 12.51 in^4)] / [((2.1)(9'x12"))^2] = 3673 lbf
Answer is therefore b.
This problem is as close as I have found to what we are looking for... although it has much structural detail. But the question still remains in my mind... the one piece of info that came from NDS... I don't know where to find.
Anybody? End-restraint coefficient C = 2.1 (from NDS). This is a timber post.
I glanced to through the tables and a couple spots in NDS, but I had no luck.
