External Buckling Pressure Calculation-Jacobsen Method

r42

m t 41mm α 0.35rad β 0.30rad µ 0.3 E 210GPa

Δ 0.0003 r Pcr 40MPa σy 690MPa γw 9810N

m3 Em

E

1 µ2

Given

rt

9π2

4 β( )2

1

π α( ) β( )

sin α( )sin β( )

2

12sin α( )sin β( )

3 α( )

πΔr

β( )sin α( )sin β( )

1tan α( ) β( )[ ] tan α( ) β( )[ ]

4

=

PcrEm

94

πβ( )

21

12rt

3

sin α( )sin β( )

3=

σyEm

t2r

1sin β( )sin α( )

Pcr r sin α( )

Em t sin β( )

14 β( ) r sin α( ) tan α( ) β( )[ ][ ]

πt sin β( )

=

αβ

Pcr

Find αβ Pcr( )

α 0.778 β 0.754 Pcr 5.856 106 Pa APcr

Pcr1.5

3.904 106 Pa

Allowable_External_Pressure_Water_HeadAPcrγw

397.947 m