No. 1 2 3 4 5 6 7 8 9 10 11
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Mark DSW DSA LL EQE EQO EQT W EQ IPO IPT FSL
Unfactored Load Item 701 A1-1 702 A1-2 703 A2-1 704 A2-2 705 B1-1 706 B1-2 707 B2-1 708 B2-2 709 B2-3 710 B2-4 711 B3-1 712 B3-2 713 B3-3 714 B3-4 715 C1-1 716 C1-2 717 C2-1 718 C2-2 719 C2-3 720 C2-4
Short Name
Long Name Ringwall Selfweight Structure Weight excluding Selfweight Live Load Tank Load for Erection Tank Contant Load Tand Hydrotest Load Wind Load Seismic Load Internal Pressure - Operating Internal Pressure - Test Fluid Surge Load
Self Wt Str. Wt Live Load EQ Erection EQ Operation EQ Test Wind Seismic Internal-Op Internal-Test Surge Load
Increase in Soil Bearing Capacity 1.00 1.00 1.00 1.00 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25 1.25
Factor of Safety (Overturning) 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00
Factor of Safety (Sliding) 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50
702 2 A1-2 1 1 0 1
704 4 A2-2 1 1 0 1
Combination Load for Unfactored Load
1 2 3 4
DSW DSA LL EQE
Self Wt Str. Wt Live Load EQ Erection
701 1 A1-1 1 1 0 1
703 3 A2-1 1 1 0 1
5 6 7 8 9 10 11
EQO EQT W EQ IPO IPT FSL
EQ Operation EQ Test Wind Seismic Internal-Op Internal-Test Surge Load
0.000 0 1 0 0 0 0
0.000 0 -1 0 0 0 0
0.000 0 0 1 0 0 0
0.000 0 0 -1 0 0 0
101 1 A1-1 1.5 1.5 0 1.5 0 0 1.5 0 0 0 0
102 2 A1-2 1.5 1.5 0 1.5 0 0 -1.5 0 0 0 0
103 3 A2-1 1.5 1.5 0 1.5 0 0 0 1.5 0 0 0
104 4 A2-2 1.5 1.5 0 1.5 0 0 0 -1.5 0 0 0
Combination Load for Factored Load
a a b a c d f g n n o
1 2 3 4 5 6 7 8 9 10 11
DSW DSA LL EQE EQO EQT W EQ IPO IPT FSL
Self Wt Str. Wt Live Load EQ Erection EQ Operation EQ Test Wind Seismic Internal-Op Internal-Test Surge Load
Long Name
e Weight excluding Selfweight
ad for Erection
ydrotest Load
Pressure - Operating Pressure - Test
Factor of Safety (Sliding) 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50
705 5 B1-1 1 1 1 1
Factored Load Item 101 A1-1 Erection + Wind 102 A1-2 103 A2-1 Erection + Earthquake 104 A2-2 105 B1-1 Operating w/o Wind 106 B1-2 107 B2-1 Operating + Wind 108 B2-2 109 B2-3 110 B2-4 111 B3-1 Operating + Earthquake 112 B3-2 113 B3-3 114 B3-4 115 C1-1 Test w/o Wind 116 C1-2 117 C2-1 Test + Wind 118 C2-2 119 C2-3 120 C2-4
Erection + Wind Erection + Earthquake Operating w/o Wind Operating + Wind
Operating + Earthquake
Test w/o Wind Test + Wind
706 6 B1-2 1 1 1 1
707 7 B2-1 1 1 1 1
708 8 B2-2 1 1 1 1
709 9 B2-3 1 1 1 1
710 10 B2-4 1 1 1 1
711 11 B3-1 1 1 1 1
712 12 B3-2 1 1 1 1
713 13 B3-3 1 1 1 1
714 14 B3-4 1 1 1 1
1.000 0 0 0 1 0 0
1.000 0 0 0 0 1 0
1.000 0 1 0 1 0 1
1.000 0 -1 0 1 0 1
1.000 0 1 0 0 1 1
1.000 0 -1 0 0 1 1
1.000 0 0 1 1 0 0
1.000 0 0 -1 1 0 0
1.000 0 0 1 0 1 0
1.000 0 0 -1 0 1 0
105 5 B1-1 1.5 1.5 1.5 1.5 1.5 0 0 0 1.5 0 0
106 6 B1-2 1.5 1.5 1.5 1.5 1.5 0 0 0 0 1.5 0
107 7 B2-1 1.2 1.2 1.2 1.2 1.2 0 1.2 0 1.2 0 0
108 8 B2-2 1.2 1.2 1.2 1.2 1.2 0 -1.2 0 1.2 0 0
109 9 B2-3 1.2 1.2 1.2 1.2 1.2 0 1.2 0 0 1 0
110 10 B2-4 1.2 1.2 1.2 1.2 1.2 0 -1.2 0 0 1 0
111 11 B3-1 1.2 1.2 1.2 1.2 1.2 0 0 1.2 1.2 0 0
112 12 B3-2 1.2 1.2 1.2 1.2 1.2 0 0 -1.2 1.2 0 0
113 13 B3-3 1.2 1.2 1.2 1.2 1.2 0 0 1.2 0 1.2 0
114 14 B3-4 1.2 1.2 1.2 1.2 1.2 0 0 -1.2 0 1.2 0
715 15 C1-1 1 1 1 1
716 16 C1-2 1 1 1 1
717 17 C2-1 1 1 1 1
718 18 C2-2 1 1 1 1
719 19 C2-3 1 1 1 1
720 20 C2-4 1 1 1 1
0.000 1 0 0 1 0 0
0.000 1 0 0 0 1 0
0.000 1 1 0 1 0 0
0.000 1 1 0 1 0 0
0.000 1 1 0 0 1 0
0.000 1 1 0 0 1 0
115 15 C1-1 1.2 1.2 1.2 1.2 0 1.2 0 0 1.2 0 0
116 16 C1-2 1.2 1.2 1.2 1.2 0 1.2 0 0 0 1.2 0
117 17 C2-1 1.2 1.2 1.2 1.2 0 1.2 1.2 0 1.2 0 0
118 18 C2-2 1.2 1.2 1.2 1.2 0 1.2 -1.2 0 1.2 0 0
119 19 C2-3 1.2 1.2 1.2 1.2 0 1.2 1.2 0 0 1.2 0
120 20 C2-4 1.2 1.2 1.2 1.2 0 1 -1.2 0 0 1.2 0
CALCULATION
CALCULATION FOR TANK FOUNDATION
4-
-
Item No. Service Type
Document -
4.1-
Refer to Dwg.No. Refer to G.A Dwg No.
LOADING DATA FOUNDATION LOADING
WEIGHT SUMMARY
4.2-
Empty Weight Operating Weight Hydrotest Weight Shear Load due to Wind Moment Due to Wind Shear Load due to EQ Moment Due to EQ Live Load
: WE : WO : WT : FW : MW : FS : MS : LL
39 234 8 12.5 32 55 11
kN kN kN kN kN-m kN kN-m kN
TANK DATA
-
Diameter of Tank = D = Bolt Center Dia = BCD =
3.012 3.172
m m
-
Height of Tank = HT =
3.000
m
-
4.3-
MATERIAL SPECIFICATIONS fy
415
MPa
fc'
25 24.00 78.50 18.00 10.00
MPa
g Concrete g Steel g Soil g Water 4.4-
kN/m3 kN/m3 kN/m3 kN/m3
SOIL CONDITION Net Soil Bearing Capacity of Area In normal operations
100
Coefficient of Lateral Soil Pressure Angle of Internal Friction Active soil pressure coefficient At rest soil pressure coefficient Passive soil pressure coefficient Coefficient of friction 4.5-
f= Ka = tan² (45 - f/2) Ko = 1 - sinf Kp = tan² (45 + f/2) m=
kPa
30 0.33 0.50 3.00 0.30
FOUNDATION OUTLINE -
Top of Ringwall Bottom of Ringwall Unit Elevation
EL + EL + EL +
14.000 11.400 13.400
m m m
b EL+ 14.000 m
DO D
h1
Di df h2
EL+ 11.400 m
-
Width of Ring wall Height of Ringwall Soil Cover Projection
b= df = h2 = h1 =
0.65 2.60 2.00 0.60
m m m m
-
Footing Outer Dia Footing Inner Dia
Do = BCD + b Di = BCD - b
3.82 2.52
m m
Page 7
CALCULATION
Areas & Moment of Inertia AF = p ( D02-Di2 ) / 4 AS = p Di2 / 4
-
Area of Ring Foundation
-
Section modulus of Ring
4.6-
LOADING AT BOTTOM OF FOUNDATION
Area of Soil Area enclosed by Tank
2
AT = p D2 / 4
5.0 7.1
m 2 m m2
S = p ( Do4-Di4 ) / 32Do
4.4
m3
404.19
KN
WF = AF * df * gConcrete
Weight of Ring Footing
% Content Load transferred to Ring ( P1 ) % Content Load transferred to Soil ( P2 ) P1 = (AT - AS) / AT * 100 P2 = 100 - P1
-
6.477
Ringwall Selfweight Structure Weight excluding Selfweight Live Load Tank Load for Erection Tank Content Load Tand Hydrotest Load Wind Load Seismic Load Internal Pressure - Operating Internal Pressure - Test Fluid Surge Load
29.89 % 70.11 %
Vertical Below Ring Below Soil NR NS kN kN 404.19
: DSW : DSA : LL : EQE : EQO : EQT :W :E : IPO : IPT : FSL
11.00 39.00 58.29 -11.66
Horizontal
M
kN
kN-m
8.00 32.00
33.30 138.20
136.71 -27.34
Notes:
Below Ring Below Soil Below Ring Below Soil
4.6-
Vertical Loading (N) LL = LL EQE = WE EQO = ( WO - WE ) * P1 EQO = ( WO - WE ) * P2 EQT = ( WT - WE ) * P1 EQT = ( WT - WE ) * P2
Horizontal Loading (H) W =Fw E =FS
Moment (M) W = Mw + H * df E = MS + H * df
STABILITY CHECKS Unfactored Loading Combination (L/C)
L/C Nos 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720
Load Combinations Erection + Wind Erection + Earthquake Operating w/o Wind Operating + Wind
Operating + Earthquake
Test w/o Wind Test + Wind
NR Below Ring (kN) 443.19 443.19 443.19 443.19 512.47 512.47 512.47 512.47 512.47 512.47 512.47 512.47 512.47 512.47 442.53 442.53 442.53 442.53 442.53 442.53
NS Below Soil (kN)
136.71 136.71 136.71 136.71 136.71 136.71 136.71 136.71 136.71 136.71 -27.34 -27.34 -27.34 -27.34 -27.34 -27.34
Moment
H
H
M
(kN) 8.00 -8.00 32.00 -32.00
(kN-m) 33.30 -33.30 138.20 -138.20
8.00 -8.00 8.00 -8.00 32.00 -32.00 32.00 -32.00
33.30 -33.30 33.30 -33.30 138.20 -138.20 138.20 -138.20
8.00 8.00 8.00 8.00
33.30 33.30 33.30 33.30
Page 8
CALCULATION
4.6.1-
Check Soil Pressure AF = p ( D02-Di2 ) / 4 AS = p Di2 / 4
6.477
Area of Soil Max soil pressure Below Ring Max soil pressure Below Soil
: PR = NR / AF + M/S : PS = NS / AS
< <
Area of Ring Foundation
L/C Nos 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 4.6.2-
Load Combinations Erection + Wind Erection + Earthquake Operating w/o Wind Operating + Wind
Operating + Earthquake
Test w/o Wind Test + Wind
2
m 2 m Pallow : Allowable Soil Pressure Pallow : Allowable Soil Pressure
NR / A
M/S
PR
PS
Pallow
(KN/m²) 68.42 68.42 68.42 68.42 79.12 79.12 79.12 79.12 79.12 79.12 79.12 79.12 79.12 79.12 68.32 68.32 68.32 68.32 68.32 68.32
(KN/m²) 7.497 -7.497 31.112 -31.112
(KN/m²) 75.92 60.92 99.53 37.31 79.12 79.12 86.61 71.62 86.61 71.62 110.23 48.01 110.23 48.01 68.32 68.32 75.82 75.82 75.82 75.82
(KN/m²)
(KN/m²) 100.00 100.00 100.00 100.00 125.00 125.00 125.00 125.00 125.00 125.00 125.00 125.00 125.00 125.00 125.00 125.00 125.00 125.00 125.00 125.00
7.497 -7.497 7.497 -7.497 31.112 -31.112 31.112 -31.112
7.497 7.497 7.497 7.497
27.37 27.37 27.37 27.37 27.37 27.37 27.37 27.37 27.37 27.37 -5.47 -5.47 -5.47 -5.47 -5.47 -5.47
Check Overturning Resistant moment : Mr = N.Do / 2 (kN-m) Safety Factor : Fo = Mr/Mo L/C Nos 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720
4.6.3-
5.0
Load Combinations Erection + Wind Erection + Earthquake Operating w/o Wind Operating + Wind
Operating + Earthquake
Test w/o Wind Test + Wind
> Mr (kNm) 846.9 846.9 846.9 846.9 979.3 979.3 979.3 979.3 979.3 979.3 979.3 979.3 979.3 979.3 845.7 845.7 845.7 845.7 845.7 845.7
Foallow : Minimum Safety Factor for Overturning Mo (kNm) 33.3 -33.3 138.2 -138.2
33.3 -33.3 33.3 -33.3 138.2 -138.2 138.2 -138.2
33.3 33.3 33.3 33.3
Fo
Foallow
Status
25.43 25.43 6.13 6.13 999.00 999.00 29.41 29.41 29.41 29.41 7.09 7.09 7.09 7.09 999.00 999.00 25.40 25.40 25.40 25.40
2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00
PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS
Check Sliding Resistant force Safety Factor L/C Nos. 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720
: Hr = 0.3 N (kN) : Fs = Hr / H Load Combinations Erection + Wind Erection + Earthquake Operating w/o Wind Operating + Wind
Operating + Earthquake
Test w/o Wind Test + Wind
> Hr (kN) 132.96 132.96 132.96 132.96 153.74 153.74 153.74 153.74 153.74 153.74 153.74 153.74 153.74 153.74 132.76 132.76 132.76 132.76 132.76 132.76
Fsallow : Minimum Safety Factor for Sliding H (kN) 8.00 8.00 32.00 32.00
8.00 8.00 8.00 8.00 32.00 32.00 32.00 32.00
8.00 8.00 8.00 8.00
Fs
Fsallow
Status
16.62 16.62 4.15 4.15 999.00 999.00 19.22 19.22 19.22 19.22 4.80 4.80 4.80 4.80 999.00 999.00 16.59 16.59 16.59 16.59
1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50
PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS
Page 9
Status PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS PASS
CALCULATION
4.7-
DESIGN OF REINFORCEMENT C. L
PS
F Di df
T
T
T = Hoop Tension =
Ka gsoil df
KaPS
4.7.1-
Factored Loading Area of Soil Max soil pressure Below Soil Hoop Stress
Hoop Tension
L/C Nos 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120
Load Combinations
2
5.0
m
20.3
kN / m
NS Below Soil (kN)
PS Below Soil (kN)
F1
F
T
(kN / m)
205.07 205.07 164.06 164.06 164.06 164.06 164.06 164.06 164.06 164.06 -32.81 -32.81 -32.81 -32.81 -32.81 -27.34
41.05121864 41.05121864 32.84097491 32.84097491 32.84097491 32.84097491 32.84097491 32.84097491 32.84097491 32.84097491 -6.568194982 -6.568194982 -6.568194982 -6.568194982 -6.568194982 -5.473495818
35.58 35.58 28.46 28.46 28.46 28.46 28.46 28.46 28.46 28.46 -5.69 -5.69 -5.69 -5.69 -5.69 -4.74
(kN) 20.28 20.28 20.28 20.28 55.86 55.86 48.74 48.74 48.74 48.74 48.74 48.74 48.74 48.74 14.59 14.59 14.59 14.59 14.59 15.54
(kN) 25.57 25.57 25.57 25.57 70.44 70.44 61.46 61.46 61.46 61.46 61.46 61.46 61.46 61.46 18.39 18.39 18.39 18.39 18.39 19.59
Erection + Wind Erection + Earthquake Operating w/o Wind Operating + Wind
Operating + Earthquake
Test w/o Wind Test + Wind
Maximum Hoop Tension 4.7.2-
AS = p Di2 / 4 PS = NS / AS F =F1 + F2 F1 = Ka PS df F2 = 1/2 Ka gSOIL df 2 T = 1/2 F Di
TMAX =
70.44
kN
Circumferencial Reinforcement AT = TMAX / fy 0.0020 * b * df AREQ =
Area of Steel for Hoop Tension = Minimum Steel Area as per IS 456 : 2000 = AMIN = Area of Steel Required =
Bar size (db) Sectional area Required No. of Bars Provide 4.7.2-
2
169.73 3461.45 3461.45
mm mm2 mm2
12 113 32
mm mm²
16 - D12 Bars on each face
Vertical Reinforcement Minimum Steel Area as per IS 456 : 2000 = AMIN =
0.0020 * b
1331.325301
Bar size (db) Sectional area Required spacing of bars DETAIL `A'
Provide
D12 @ 165 mm c/c on each face
Page 10
12 113 170
mm²/m mm mm² mm
DESIGN OF RING WALL ANNULAR RAFT Materials Grade of Concrete Grade of Steel
25 N/sq.mm 415 N/sq.mm
Size of Ring Wall Width of Ring Wall Central Diameter of Ring Wall, C Depth of Ring Wall above FGL Depth of Foundation above raft Depth of Raft Safe bearing capacity Unitweight of Soil Empty Weight of Tank Operating Weight Wind moment Seismic Moment Shear at Base Due to Wind Shear at Base Due to Seismic Area of Ring Wall Weight of Ring Wall above Raft Wieght of soil above Raft Total Vertical Load on Raft Total Moment due to wind at Raft Total Moment due to earthquake at Raft Width of Raft External Diameter of Raft, D1 Internal Dia meter of Raft, D2 Weight of Ring Wall Check for Bearing Pressure Area of Raft Section Modulus of Raft Max Bearing Pressure under the Raft P/A+M/S Increaseing SBC @ 25% Pact<1.25SBC,Hence Safe Design Moments Modified uniform pressure p = p1+0.5p2 Outer Radius of Raft, a Inner Radius of Raft, b Central Radius of Raft, c As per clause no. 5.1.2 of IS :11089-1984 At radius, r = 0.861m (Inner Face of Raft) pa^2/16 2
2
b /a
0.65 3.12 0.60 2.00 0.40 100 18 39 234 12.5 55 8 32 6.38 398.11 264.60 896.71 30.1 125.4 1.4 4.522 1.722
m m m m m kN/sq.m kN kN kN kNm kNm kN kN kN kN kN kNm kNm m m m
13.73 sq.m 8.89 cu.m 82.8 kN/sq.m 125 kN/sq.m
74.06 2.261 0.861 1.561
kN/sq.m m m m
23.663 kN 0.145
2
2
1.000
2
2
0.145
2
2
b /r r /a
c /a Mt Mr At radius, r = pa^2/16 2
0.477 -82.717 kNm 59.259 kNm 2.261m (Outer Face of Raft)
2
b /a 2
2
c /r c/r Mt Mr Maximum Moments for Design Mt Mr Check for Effective Depth Required effective depth, dr Provided effective depth, dp Reinforcement Calculation Circumferential Reinforcement 2 Mu/bd Area of steel Required Provided diameter of Steel
23.663 0.145 0.145 0.690 -61.143 kNm 92.569 kNm 82.717 kNm 92.569 kNm 141.02 mm 350 mm
2 0.482 N/mm
654.77 mm 12 mm
2
Check Min Steel
2
420 mm / m width 170 mm
Min Area of Steel Spacing of Reinforcement Required Radial Reinforcement 2 Mu/bd
2 0.7557 N/mm
Area of steel Required
743.16 mm
2 2
Check Min Steel
Min Area of Steel 420 mm / m width Provided diameter of Steel 12 mm Spacing of Reinforcement Required 150 mm Provide 12mm diameter bars @170mm C/C circumferentially Provide 12mm diameter bars @150mm C/C radially
Design of Concrete Ring Beam for Storage Tank In this page I will talk about the design philosophy of ring beam for storage water tank. The granular fill foundation of the tank shall Sometimes clients ask to provide concrete ring beam around tank foundation. Prevent uplift of the tank due to wind or earthquake Prevent edge failure of the soil at the tank shell Prevent local uplift of the tank due to internal pressure. Now you will follow the following steps to start the foundation load calculation and design: Step-1 : Review of Tank detail drawing (Vendor Drawing) You need to review tank drawings from foundation design point of view and check whether you have all the following information: Tank Dimension, Diameter and Height Type of Roof (Floating or fixed roof), weight of roof Detail of tank shell and weight of tank shell Detail of tank base plate, location of base sump, annular plate and total weight of base plate Detail of anchor bolt (BCD, no of bolt and dia of bolt) and anchor bolt fixing detail Location and detail of man-hole at bottom portion of tank Product density and and maximum height of product Maximum height of water inside the tank for the hydrotest* Internal pressure or suction Live load Wind Shear and moment on tank shell Seismic shear and moment on tank shell Step-2 : Verification of foundation location, elevation and external fittings loads
You need to review Plot plan, Equipment location drawings and 3 -D Models and check whether you have all the following informat Verify the area available for foundation. Verify Foundation location and Elevation Pipe supports and Nozzle loads on tank (Dp) Location and size of Platforms around the tank Locations of underground pipes Electrical and Instrument duct banks Locations and extent of adjacent foundations Verify the location and extent of new/existing foundations not shown in 3D model or plot plan. Step-3 : Loads on concrete ring beam and on the confined compacted granular fill in-side the ring:
You need to place concrete ring beam in such a way that outer surface of the tank shell should be the center of ring beam. Conside Geotechnical Data: Before starting the design, you need to collect the following information about soil: Allowable Bearing Pressure Density of Soil Co-efficient of earth pressure at rest (Ko) Loads on Ring beam: Total weight of tank shell (vertical load), kN / m (DL)
Total weight of roof , for fixed roof case. For floating roof, part of the roof weight will come on the ring beam, kN / m (DL) Total live load on roof , for fixed roof case. For floating roof, part of the live load will come on the ring beam, kN / m (LL) Part of annular base weight on ring beam, kN / m2 (DL) Part of product / test water load on ring beam, kN / m2(PL) Seismic shear and wind shear on ring beam, kN / m Part of internal pressure / suction load on ring beam, kN / m 2(IP) Loads on compacted granular fill inside the ring beam: Floating roof weight on compacted granular fill, kN / m 2(DL) Annular base weight on compacted granular fill, kN / m 2 (DL) Live load on floated roof, kN / m2 (LL) Product / test water load on compacted granular fill, kN / m 2(PL) Internal pressure / suction load on compacted granular fill, kN / m 2(IP) Following load combimations can be used for soil bearing pressure check (at bottom of ring beam level) :
Load Combination: LC1 - Self weight of soil / Beam + Self weight of tank + Product weight + Internal pressure Load Combination: LC2 - Self weight of soil / Beam + Self weight of tank + Product weight + Internal Pressure + Live Load Load Combination: LC3 - Self weight of soil / Beam + Self weight of tank + Product weight + Internal pressure + Wind Load Load Combination: LC4 - Self weight of soil / Beam + Self weight of tank + Product weight + Internal pressure + Seismic Load Load Combination: LC5 - Self weight of soil / Beam + Self weight of tank + Product weight + Internal pressure + Live Load + Win Load Combination: LC6 - Self weight of soil / Beam + Self weight of tank + Product weight + Internal pressure + Live Load + Seis Load Combination: LC7 - Self weight of soil / Beam + Self weight of tank + Test water weight Load combinations for Ring beam design for Hoop tension:
Load Combination: UC1 - 1.7 x (Surcharge load of confined soil) + 1.7 x Surcharge load of (Self weight of tank + Product weight + Load Combination: UC2 - 1.7 x (Surcharge load of confined soil) + 1.7 x Surcharge load of (Self weight of tank + Product weight + Load Combination: UC3 - 1.7 x (Surcharge load of confined soil) + 1.7 x Surcharge load of (Self weight of tank + test water weigh Step-4 : Determination of concrete ring beam size:
The ring wall should be a minimum 300 mm thick and extend to a suitable bearing stratum, whch may be natural ground or built-up
API 650, appendix-B, clause B.4.2.2 states that it is desireable that the ringwall width be such that the average unit soil loading und
Once, the ringwall thickness is determined from above condition, it should be reviewed to ensure that excessive quantities of concr
Please note that, soil bearing pressure under the ring beam and under the confined earth at same depth should not exceed the allo Step-5 : Determination of Hoop Tension on concrete ring beam and reinforcement calculation:
The concrete ring beam shall be designed for hoop tension. This hoop tension will be generated from surcharge load due to confin Load calculation: Surcharge due to confined soil: Sursoil = 0.5 x (height of ringwall)2 x soil density x Co-efficient of earth pressure at rest (Ko)
Surcharge due to uniform load on confined soil: Surudl = (Load on confined soil) x (height of ringwall) x Co-efficient of earth pressu Total Hoop tension (T) = (Sursoil + Surudl) x (0.5 x centerline diameter of ring beam) Factored Hoop Tension load can be calculated as per step-3. Required area of Hoop reinforcement is, Ast = (Factored Hoop tension) / (0.9 x yeild stress of rebar---fy)
The ringwall must also be designed to take care circumferential bending moments due to the vertical load being applied eccentrica
The ringwall should be reinforced on both faces, with vertical reinforcement (stirrups) closest to the concrete surfaces. Not more th Step-6 : Anchor Bolt Design:
Anchor bolt shall be checked per design criteria and Tenssion & Shear load supplied by vendor. If wind and shear forces are not su
orage Tank
The granular fill foundation of the tank shall be designed per project design criteria / specification. This type of foundation is mostly common to all proje
ether you have all the following information:
k whether you have all the following information:
ll should be the center of ring beam. Consider the following loads on ring beam and on granular compacted fill inside the concrete ring.
come on the ring beam, kN / m (DL) ome on the ring beam, kN / m (LL)
weight + Internal pressure weight + Internal Pressure + Live Load weight + Internal pressure + Wind Load weight + Internal pressure + Seismic Load weight + Internal pressure + Live Load + Wind Load weight + Internal pressure + Live Load + Seismic Load
oad of (Self weight of tank + Product weight + Internal pressure) oad of (Self weight of tank + Product weight + Internal pressure)+ 1.4 x surcharge of Live Load oad of (Self weight of tank + test water weight)
tum, whch may be natural ground or built-up compacted granular material. It should be 500 mm below ground level and extend below frost line. The be
be such that the average unit soil loading under the ring wall will be approximately equal to the earth pressure under the confined earth at the same dep
d to ensure that excessive quantities of concrete are not used for tanks with low liquid levels and that the permissible ground pressure for the width of th
arth at same depth should not exceed the allowable soil bearing pressure for any of the above described load and any load combinations.
generated from surcharge load due to confined soil and loads on confined soil.
efficient of earth pressure at rest (Ko)
ght of ringwall) x Co-efficient of earth pressure at rest (Ko)
e to the vertical load being applied eccentrically to the ringwall center line.
closest to the concrete surfaces. Not more than 50% of the hoop reinforcement should be lapped at any one position.
by vendor. If wind and shear forces are not supllied by vendor, you need to calculate the anchorage load from API 650. Anchor bolt shall be designed fo
e of foundation is mostly common to all project site. However, sometimes we design concrete ring beam around the tank foundation. Following are som
d fill inside the concrete ring.
und level and extend below frost line. The bearing capacity of the soil below the ringwall should be calculated using a strip foundation analysis loaded w
ure under the confined earth at the same depth (in maximum liquid level condition).
ermissible ground pressure for the width of the wall is not exceeded.
ad and any load combinations.
om API 650. Anchor bolt shall be designed for ductility failure. If required, additional reinforcement to be provided around the anchor bolt.
round the tank foundation. Following are some reasons for design of concrete ring beam, though this is more costly and take longer to construct than g
ted using a strip foundation analysis loaded with vertical load as mentioned in step-3.
ovided around the anchor bolt.
ore costly and take longer to construct than granular fill ring:
FOUNDATION
Design and building of steel construction of the tank can not be done without taking into account the relation between upper steel construction and soil basement. Inclusion of coefficient of the bed K b in solution of contact problem in the joint shell bottom is not sufficient.The badly designed or badly executed foundations can cause failure condition of the tank and at least it can lead to differential settlement. Welded spatial constructions with thin walls are flexible and they are very sensitive to the 1. Shape of the bottom a) cone up bottom This is more often used bottom shape. It allows water drains from inside of the tank to the situated near to the shell draw-off sump. The atmospheric waters do not move toward to the center of the tank and are not kept bellow the bottom. b) cone down bottom. This type of bottom is applied when the tank often must be emptied / filled. Value of the slope is the same as the slope of the cone up bottom. It assures full drain of the water dropped inside in the tank and minimal contact surface between the water inside and the bottom. One of the weaknesses is the possibility for keeping and storing the atmospheric water felt below the c) flat bottom without slope It can be applied in the small tanks where the removing of the water dropped inside into the tank is not required. Can bebottom appliedwith where the slope. diameter D ≤ 30 m. This type of bottom requires sloped foundation and the construction of the shell d) flat single must assure its vertical position. 2. Type of foundation construction a) foundation from compacted soil (earth type foundation). This is most often applied scheme of foundation construction because it is cheapest and easiest for execution. It is made according to the scheme shown in API Std. 650. It is used when the soil can bear the pressure of the upper steel construction and when the anchorage is not necessary. Even when there is small leak moving out of the soil is possible. It can leads to destruction of the tank. In this reason the diameter of the tank must be bigger than the diameter of the tank with not less then
Earth type foundation b) reinforced concrete ring which is not placed under the shell. The tanks which are subject of this research are the above ground facilities. They are placed on 0,3 ÷1,2 m above the soil. This level difference is remarkable in the fuel oil tanks where pump always must be under the liquids (Δh ≥ 0,7m). If the classical earth type foundation reaches this height the facility must occupy remarkable surface on the site. The reinforcing of such In order to avoid this inconvenience appears the idea of small foundation ring between the ground and the bottom level which ring is a combination free sand pillow and reinforced concrete ring in the periphery. The proposed construction is similar to the API Std. 650, but the foundation ring is moved in the outside direction where it can not be influenced of the load of the shell and the tank roof upon it. When there is soil settlement under the tank, the reinforced concrete ring does not allow full drain of
Reinforced concrete ringwall foundation which is not placed under the shell c) reinforced concrete ring wall foundation. The trend in the tanks building shows that the volumes of the facility increase. Spatial steel construction of the tanks stands more flexible. In this reason bigger attention must be paid to the shell settlement and to the prevention measures. The use of the rigid reinforced concrete ring increase around the world. When the tanks are bigger the dimensions of the rings are: largeness not less then 0,6 m and height 1,5 – 2,0 m.This type foundation construction allows very good leveling of the
Reinforced concrete ringwall foundation d) reinforced concrete slab They are applied when the tanks are relatively small because this type of foundations is very expensive. This type of foundation is more favorable for upper steel structure. They do not allow the uneven settlement of the tank. The reinforced concrete slab is very recommendable when the level of the underground water is high.
Reinforced concrete slab The special foundation constructions as the foundation in the weak soil must be executed according to the concrete projects after the technical and economical analysis made on the ground of results of the geological and engineer research.
