PSI - Issue 36

Mykhailo Hud et al. / Procedia Structural Integrity 36 (2022) 79–86 Mykhailo Hud / Structural Integrity Procedia 00 (2021) 000 – 0 0

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and annular cross section. In a cylindrical shell 1 r   .     2 2 1 2 2 r r c f f u N y P y y h x y P     where is a coefficient of working conditions, 1 f y ,

2 f y is a load reliability coefficients.

Ring tension, at the level x : 







r

y y h x y P  

N t

1

2

2

f

f

u

2  

2 

t

cm

cm









2 r

y y h x y P

y R  

Cylindrical tank wall thickness:

t

1

2

f

f

u



cm

c

Wall deflection (radial movement):     2 2 r r u y h x P  

P P

,

y r

 

 

Et

Et

K

cm

cm

cm

where: is a wall bed ratio. Calculation of the tank wall for stability by American Water Works Association (1985). Loads acting on the tank cover and on the wall (snow, wind, thermal insulation, own weight, excess pressure and vacuum), in various combinations cause axial and transverse compression in the wall, as a result of which the wall in some cases may lose stability. The wall is calculated for axial compression according to DBN B.2.6-198: 2014. The stability of the wall is checked by the formula: 1 1 c ct y    where: 1  - design stress in the shell, 1 ct  – critical tension, at the level : equal to the lesser of the values  R y or / cEt r (where r - the radius of the middle surface of the shell, t - shell thickness). Values of coefficients  at 0 / 300 r t   should be determined by the formula by American Society of Civil Engineers (1984): R r 0.97 (0.00025 0.95 ) y E t      The calculation of the stability of a closed circular cylindrical shell of rotation under the action of external uniform pressure P , normal to the side surface, should be performed by the formula by American Society of Civil Engineers (1984): 2 2 c cs y    , where: 2 Pr/ t   - calculated annular stress in the shell; 2 cs  - critical stress, determined by the formulas: when 0.5 / 10 l r   ,    3/ 2 2 0.55 / / E r l t r   when / 20 r l    2 0.17 / cs E t r   when 10 / 20 l r   stress 2 cs  should be determined by linear interpolation. Here l is the length of the cylindrical shell. The same shell, but supported by annular ribs located with a step 0.5 S r  between axes, should be calculated on stability according to the above-stated formulas with substitution in them of value S instead l. A closed circular cylindrical shell, subject to the simultaneous action of loads that cause axial and transverse compression, is tested for stability by the formula by American Water Works Association (1985):

1    

y

2  

c

1

2

cr

cr

1.2 Calculation of a vertical steel cylindrical tank for seismic impact using a software Lira The design of a vertical steel tank (VST) with a volume of 4500 m 3 for storage of oil products is taken as a