Page 41 - Civil Engineering Formulas

r = 0.264r
9π 2 – 64
6π
= 0.1908r 3
= 0.2587r 3
= 0.4244r
c 1
c 1
c 2
I
I
r) 4 R 2 + Rr + r 2 2I = c 1 R + r 3π π (R 2 – r 2 ) = 0.31r 1 (approx) R – c 1 = c 2 a πa 2 b I 0.7854a 2 b = = 2 4 c I π I (πab – a 1 b 1 ) (a + 3b)t a = 4 c a + 3b a (approx) = a + b 2 (approx)
– is very small 0.7854a 3 b (approx)
8 9π r + (a 3 b – a 1 3 b 1) (a + 3b)t
_ 0.283R 2 r 2 (R R t =
π 8 = 0.1098r 4 I = 0.1098 (R 4 – r 4 ) = 0.3tr 1 3 (approx) when r 1 πa 3 b 4 a 2
I = r 4 – I = π I = 4 π = 4
(Continued)
a
r R
r 1
t
a
b
r
b t
FIGURE 2.1
b 1
t
2
2
c
c
1
1
c
c
1
a
17