Fuel Tank Ring Beam Design Calculation

Fuel Tank Ring Beam Design Calculation This Design Calculation for Ring Beam Design for Fuel Tank at Bamenda Powe r Plant is based on the Design Guidelines provided by "Process Industry Practices Structural: PIP STE03020 -Guidelines for Tank Foundation De signs". Concrete Design is according to the BS 8110:1997 and ACI 318 as applies relevantly. Loading for Fuel Tank: Ultimate Limit State loads for foundation design work, from Fuel Tank Designer Shop Drawing, attached in Appendix 1 permanent loads at empty and full conditions, P1e, P1f P1e := 593kN

P1f := 6970kN

Operation loads at empty and full conditions, P2e, P2f P2e := 113kN

P2f := 113kN

Normal Wind loads at empty and full conditions, P3e, P3f P3e := 60kN

P3f := 60kN

Extreme Wind loads at empty and full conditions, P4e, P4f P4e := 103.5kN

P4f := 103.5kN

Service Limit State loads for foundation design work, from Fuel Tank Designer Shop Drawing, attached in Appendix 1 permanent loads at empty and full conditions, p1e, p1f p1e := 395kN

p1f := 4648kN

Operation loads at empty and full conditions, p2e, p2f p2e := 75kN

p2f := 75kN

Normal Wind loads at empty and full conditions, p3e, p3f p3e := 40kN

p3f := 40kN

Extreme Wind loads at empty and full conditions, p4e, p4f p4e := 69kN

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p4f := 69kN

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Tank Geometrical Data ( from vendor drawing-attached in Appendix 2): Tank Diame te r, Dt

Dt := 9500mm

Tank He ight, Ht

Ht := 6000mm

Wall Plate Thickness,WPt

WPt := 6mm

Bottom Plate Thickness,BPt

BPt := 6mm

Height of liquid, Hl

Hl := 5500mm

Densities of Material contributing loads: kN

γf := 8.32

Density of Fuel, γf

m γst := 78.50

Density of Steel, γ.st

3

kN m

γc := 24

Density of Concrete, γc

3

kN m

3

Soil Parameters: Soil Repose angle ϕ and Active Pressure Coefficient, ka ϕ := 35deg

ka :=

1 − sin ( ϕ )

1 + sin ( ϕ )

Passive Coefficient of Soil , Kp and Cohesion Intercept , Cs.

1 kp := ka

Cs := 5

kN m

2

Soil Bearing Capacity, SBC as per Soil Investigation Report: SBC := 1.2bar Density of Soil, γs

γs := 18

kN m

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Concrete Design Data: fcu := 29

N 2

mm fy := 460

N 2

mm

Ring Beam Dimensions:

ring beam width,br

hr := 1000mm br := 400mm

ring beam diameter, dr

Dr := 9500mm

ring beam height, hr

> minimum ring beam width 300mm as per Tank S hop Drawing she ll diameter matching with ring beam diameter to transfer load minimum eccentricity.

Design of Ring Beam-part 1 -Soil Bearing Capacity Consideration Soil Bearing Pressure under Ring Beam and the infill soil pressure at the same bottom level of the foundation should be kept equal as far as possible, to avoid settlement due to punching shear. So for this reason first it will be calculated the Shell Wall weight [Ww] directly transferring onto the Ring Beam with self weight [Fsw] of the ring beam. This total Soil Pressure will be compared against the infill soil pressure to see the difference.

Empty Tank Load on SLS will be considered as the Shell Wall loading onto the Ring Beam, hence approximate Actual Shell Wall Load without fixing arrangements and accessories, AWw, 2

 Dr  π ⋅   ⋅ WPt ⋅ γst 2 AW w := WPt ⋅ Ht ⋅ γst + ⋅2 π⋅ D r

AW w = 5.063 ⋅

kN m

1.25 ok

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FORCES ON RING BEAM

Surcharge load and infill soil load stress at Ring Beam bottom level: Loading onto the Soil Fill as surcharge, Ss

S s :=

p1f + p2f

 Dr br  π⋅  +  2  2

+ hr ⋅ γs = 79.356 ⋅ 2

kN m

2

S s = 79.356 ⋅

Soil Bearing Pressure under tank, Ss

kN m

2

actual soil loading based on Tank De signer S LS Loading Data is highe r than the pure Fuel and Soil pressure loading, below shown, hence Ss calculation is conservative. Hl ⋅ γf + hr ⋅ γs = 63.76 ⋅

kN m

σrwsw Ss

= 1.014

2

ratio between ring beam bottom soil pressure and infill soil inside, approx =1.

at SLS the pressure under Ring Beam is approximately equal to the SLS soil pressure due to infill, hence the Ring Beam width is sufficient.

Ring Beam width, br

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br = 400 ⋅ mm

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At ULS , with Fuel filled up to allowable full height of the tank, the soil pressure under Ring Beam, 2 2  D  P1e   r br   Dr   + RBsw ⋅ π ⋅ Dr + W f ⋅ π ⋅  +  − π⋅     π ⋅ Dr 2 2    2   ULSσrwsw := 2 2  D  r br   Dr br   π ⋅  +  − −  2  2   2 2

ULSσrwsw = 97.035 ⋅

kN m

SBC

= 1.237

ULSσrwsw

2

> 1.2 ok

Ring Beam Wall Design Lateral loading transferred into the wall are two types, one is from the infill soil lateral pressure and the other will be from surcharge load due to the tank weight and fuel inside. Due to infill soil, p1 := ka ⋅ hr ⋅ γs

p1 = 4.878 ⋅

kN m

2

due to surcharge of the Tank weight unde r SLS conditions, p2 := ka ⋅ S s

p2 = 21.505 ⋅

kN m

2

Lateral Force on Ring Beam per unit length,

F1 :=

p1 ⋅ hr

+ p2 ⋅ hr

2

kN F1 = 23.944 ⋅ m

Hoop Tension Calculation,

HT :=

F1 ⋅ Dr 2

= 113.732 ⋅ kN

HT

= 2.513

 12mm 

0.87 ⋅ fy ⋅ π ⋅ 

 2

2

 

to take this Hoop Tension, 3 nos of T12 bars are enough, hence check for the ULS for minimum reinforcement requirement.

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hr Dr  ka ⋅ P1f ⋅ hr + ka ⋅ hr ⋅ γs ⋅  ⋅  2 2   Dr  2 π⋅     2  = 3.052 2 12mm  0.87 ⋅ fy ⋅ π ⋅    2 

this confirms that reinforcement detailing must be dominant to this design of tension reinforcement.

Minimum Reinforcement Requirement for the Ring Beam, treating it as a pure Tension Member, as per Table 3.25 BS 8110: 1997 Part 1: Code of practice for design and construction,

(

Asmin := 0.45% ⋅ hr ⋅ br Asmin

  12mm  2 π ⋅     2 

)

2

Asmin = 1800 ⋅ mm

= 15.915

16 bars of T12

For Vertical minimum reinforcement requirement, as per the Design Guidelines of "PIP STE03020 -Guidelines for Tank Foundation De signs" re com mending ACI 318 code requirements,

(

Avsmin := 0.0015 ⋅ hr ⋅ br Avsmin

  12mm  2 π ⋅     2 

)

2

Avsmin = 600 ⋅ mm

= 5.305

6 bars of T12

provide 16T12 in longitudinal direction and T12@150mm in lateral direction. Design Check for Shear Shear Load on the Ring Beam, νs Ww N νs := = 0.033 ⋅ br 2 mm effective depth of the Ring Beam, d1 d1 := hr − 60mm − 12mm −

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12mm

d1 = 922 ⋅ mm

2

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material factor, γm := 1.25 Design Shear Stress calculation, considering tension r/f provided, the Design Concrete Shear Stress τC as per BS 8110: 3.5.5 Shear resistance of solid slabs, 1 3

1 2 1    100 ⋅ π ⋅  12mm  ⋅ 16 3 4  2     400mm   fcu      ⋅ d  ⋅ br ⋅ d1 N  1     25  2 mm   νC := 0.79 ⋅ γ

m

N 2

mm

N

νC = 0.425 ⋅

2

mm νC νs

= 12.847

Shear Reinforcement is not required.

Checking For Wind Loading for Stability: Fuel Tank Diameter and He ight is within limits as following that Wind Analysis is not re quir ed.

Ht Dt

= 0.632

which is less than 1 , no need to check for lateral loading of wind.

Even though this Fuel Tank is not anchor ed to the Foundation hence check m ust be done for overturning which following criteria is adopted, reference: Saudi Aramco Best Practice, SABP-005 - 31 August, 2002/ Storage Tank Ringwall Foundation Design. Overturning Moment under ULS, for extreme wind force, Mot := P4f ⋅ Ht

Mot = 621 ⋅ kN ⋅ m

Resisting Moment under ULS, for empty tank, with 2/3 reduction, Dr 2 Mr := ⋅ P1e ⋅ 3 2 Mr Mot

= 3.024

Mr = 1877.833 ⋅ kN ⋅ m hence safe.

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Soil Bearing Pressure check for ULS lateral forces: Section Modulus for the Ring Beam Foundation, Zxx

 D + b 4 − D − b 4  ( r r) ( r r)  Zxx := π ⋅   32 ⋅ ( Dr + br)  

Zxx = 27.256 ⋅ m

3

due to extreme wind forces under ULS conditions, the soil stress increment due to the over turning moment, is calculated below for upper limit and lower limit, upper limit must be checked for Soil Bearing Capacity. Mot σ1 := σrwsw + Zxx

σ1 = 103.234 ⋅

Mot σ2 := σrwsw − Zxx

σ2 = 57.665 ⋅

σ1 < SBC = 1

kN m

OK

SBC = 120 ⋅

kN m

2

kN m

2

2

under ULS lateral loading conditions , Fuel Tank Foundation soil pre ssur es are safe .

R/F DETAIL FOR RING BEAM

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CONCRETE DETAIL FOR RING BEAM

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APPENDIX VENDOR SHOP DRAWING FOR FUEL TANK-PART ABSTRACTED

LOADING DETAILS FROM FUEL TANK DESIGNER SHOP DRAWING

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