Page 39 - Civil Engineering Formulas
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Moment of inertia Radius of gyration Section modulus d r A πr 3 πd 3 I A πr 4 = r = = = r 2 = = c 4 2 4 4 32 4 4 (approx) 0.1d 3 = (approx) π I D 4 – d 4 = (D 4 – d 4 ) c D 32 R 4 – r 4 π = (R 4 – r 4 ) D 2 + d 2 R 4 + r 2 R 4
= πd 4 64 0.05d 4 = π = 64 π = 4 A = 4
I I R
d m = (D + d) s = (D – d)
r
Section d d 1 2 1 2
r
D
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