CIVIL ENGINEERING FORMULAS

R

r

r

d

dm = (D + d)

(D^4 – d^4 )

s = (D – d)

D

d

R^4 + r^2

2

I=

π

64

I= = r^2

πd^4

64

πr^4

4

=

A

4

=π(R^4 – r^4 )

4

A

4

= (R^2 + r^2 )

= 0.05 (D^4 – d^4 ) (approx)

D^4 – d^4

D

π

32

D^2 + d^2

2

R^4 – r^4

R

=

=

π

4

when is very small

= 0.8dm^2 s(approx)

=0.05d^4 (approx)

= r

πd^3

32

πr^3

4

=

A 4 1 2 1 2

I

c

=0.1d^3 (approx)

=

I

c=

d

4

r

2

s

dm

=

Section Moment of inertia Section modulus Radius of gyration

16