design calculation for rc ring beam

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Structural Calculations for Ring Beam Foundation to 44-mSteel Tank at Musalla Blending StationTable of contentspage

31Introduction

32Design Criteria

32.1Materials

32.2Loads

32.3Soil Conditions

32.4Other Parameters

32.5Codes and References

43Analysis Considerations

43.1Numerical Models

64Load Calculations

64.1Vertical Load

74.2Lateral Loads

84.3Loading Diagram

95Analysis and design

95.1Check bearing pressure below ring beam

105.2Calculation of support springs (for Finite Element Model Analysis)

115.3Calculation of support displacements loads (for Stick Model Analysis)

125.4Analysis

125.5Design

146Details

15Attachment 1- Loading Data from Ishii Iron Works

16Attachment 2- Differential Settlement Information/Subgrade Reactions

17Attachment 3- Numerical Model and Loading Diagram

18Attachment 4- Finite Element Analysis of Ring Beam

19Attachment 5- Stick Model Analysis of Ring Beam

1 Introduction

This document contains design calculations for ring foundation to support a proposed 44-m diameter steel tank at Musalla Blending Station.

2 Design Criteria2.1 Materials2.1.1 Concrete

Concrete strength, fc=40 N/mm2

Modulus of elasticity, Ec=28000 N/mm2 (approx)

2.1.2 Reinforcing Steel

Reinforcing yield strength, fy= 460 N/mm2

Modulus of elasticity, Ec=200000 N/mm2 (approx)

2.2 Loads

2.2.1 Live load

Desity of Liquid= 10 kn/m3

2.2.2 Dead load

Concrete Unit Weight= 24.0 kN/m3

2.2.3 Tank Loading Data

Superimposed loads are based on Loading Data prepared by Ishii Iron Works (Attachment 1).

2.3 Soil ConditionsSaturated Density= 19 kn/m3 (Type B)

Coefficient of Pressure, Ko= 0.5 (Type B)

Max differential Settlement=65 mm (based from B&V Specifications See Attachment 2).

Minimum Subgrade Reaction*=20000 kN/m3

Maximmum Subgrade Reaction*=80000 kN/m3

*Fill material to be used for the site is assumed similar to that proposed for Salmabad Forwarding Station (See Attachment 2)2.4 Other Parameters

Coef. of friction bet. stl plate & conc.= 0.3 Eccentricity due to const. tolerance= 50 mm

2.5 Codes and References B&V Specifications dated Aprill 2005 (T1-Contract No. 0380/2004/3100)

Loading Data from Ishii Iron Works Co. Ltd. (Attachment 1)

BS8110 Part 1: Structural Use of Concrete

Reinforced Concrete Designers Handbook by Reynolds and Steedman

Foundation Engineering Handbook by Winterkorn and Fang

3 Analysis Considerations

3.1 Numerical Models

STAAD software was used to analyse the numerical models for the Ring Beam.

3.1.1 Finite Element Model

Attachment 3 presents the finite element model and the diagrams of loadings applied in the model.

The ring beam is simulated into a series of 3d model finite elements. Estimated required soil bearing pressure and varying settlement (considering a maximum differential settlement of 65 mm ) were represented as vertical springs acting at the bottom of the elements. The vertical load due to weight of tank will be considered acting eccentric, beyond the centreline of the ring beam. To represent this condition a fictitious member projecting outwards the ring, at the top joint of the topmost elements were provided. Similarly, the vertical load due to weight of water also acts eccentrically at the inner side of the ring beam centreline. This is represented by fictitious member projectecting inwards the ring, at the top joints of the topmost elements. Calculation of lengths of the fictitious members were presented in this calculation

3.1.2 Stick Model

For determining total required bottom reinforcements, a stick Model (Attachment 5) was simulated considering the same loading conditions as the finite element model, in addition to suppport load displacements applied to the semi-circle portions of the ring beam.

The model is analysed to check the worst case between the maximum and minimum possible values of subgrade reaction of the backfill (Attachment 2).

3.1.3 Loading

3.1.3.1 Vertical loads

Vertical loads from the tank shell were imposed on the ring beam were derived based on loading data (furnished by Ishii Iron Works).

Load of liquid, in contact with the ring beam was also included. Height of liquid according to the loading data is 20.20 m, based on 1013 atm bar normal atmospheric pressure.

3.1.3.2 Lateral loads

Lateral loads acting from soil, against the ring beam are as follows:

Soil pressure due to saturated bulk density

Hydrostatic pressure

Surcharge due to weight of tank bottom plate and weight of contained water.

Passive resistance against the ring foundation is ignored in the analysis due to possible future unplanned excavation at the external face of the ring beam.

3.1.3.3 Support displacement load (for Stick Model Analysis)

Support displacement load has been considered in the stick model by applying varying values spread over half the circumference of the ring beam. The maximum support displacement load considered is 65 mm, based on maximum differential settelement required by B & V(Attachment 2).

3.1.3.4 Other loadings

The tank bottom plate is expected to resist bending from the shell and from the intermediate columns. Since there is no rigid connection from the tank to the ring beam, no moment transfer due to normal loads, earthquake and wind forces are considered in the analysis of the ring beam. However, horizontal load due to seismic condition, based in Ishii Iron Works Loading data, were applied in the analysis of model, considering frictional force between the bottom of the tank filled with water, and top of ring beam.

4 Load Calculations4.1 Vertical Load

Load due to Steel weight along shell perimeter

WTS= 5717 kN (From Ishii Iron Works. Refer to Sht 3 & 4 of Attachment 1)

D= 44 -m

WTS/m=5717/(X D)

=41.36 kN/m

Joint applied to STAAD Model (Consider 1.0 -metre strip):FyTS=41.36 X 1

=41.36Kn

Location of FyTS from centreline of ring beam:

efyts=construction tolerance + max. thickness of sheel + offset of shell from centreline of ring beam

efyts=0.05m + 0.0217 m/2 + 0.050 m

=0.1109 m projected beyond the centreline of ring

Load due to weight of water in contact with ring beamHt of liquid=20.20 m based on 1013 mbar (normal pressure)

Considering thickness of ring beam as 0.8 metre, and the 44 tank is offset by 50 mm beyond the cetnreline of the ring beam, the contact area, Ac, of water is calculated as:

Ac=( / 4) x {442 [44-2x(0.8/2+0.05)]2}

=( / 4) x (442 43.12)

=61.57 m2WH2O=61.57 X 20.20 X 10 Kn/m3

=12437.14 kN

Joint applied to STAAD Model (Consider 1-metre strip):The diameter Dw which is the location of centreline of water in contact with ring is calculated as:

Dw=44-2x[(0.8/2+0.05)/2]

=43.55 m

FyH2O=(12437.14/Dw) X 1-m strip

=90.90 kN Location of FyH2O from centreline of ring beam:

efh2o= (offset of shell from centreline of ring beam + width of the ring beam)efh2o= (0.05m + x 0.8m)

=0.225 m projected inside the centreline of ring

4.2 Lateral Loads

Surcharge

Psur=Load of bottom plate + Bottom pressure of contained water

={ [ 1060 kN / ( 442/4) ] + 10 x 20.2} Ko

=101.35 kN/m2

Psur

Soil Pressure (Active)

Consider Height of Ring Beam, H = 1.1 m

PSOIL=(s - w) H Ko

=(19 10) (1.1) (0.5)

=4.95 kN/m2

Pactive Hydrostatic Pressure

PHYDRO=w H

=10 x 1.1

=11 kN/m2

PHYDRO Earthquake Force (FH = 13810 kN from Ishii Loading Data)

FEQ=(13810 /D) X 1-m strip

=99.91 kN

Based on Ishii Loading data, the FH for the shell was calculated considering total weight of shell, including weight of contained liquid. Considering weights in contact with ring beam acting against the given earthquake force, total resistance is computed as the product of the weight of tank shell loaded with liquid and coefficient of friction between tank and concrete (assume 0.3).

FR=0.3 X [(WTS + WH2O) / D] X 1-m strip

=0.3 X [(5717+12437.14)/D] X 1-m strip

=39.40 kN

FHEQ=99.91 39.40 =60.51 kN

Wind Force (FW = 851 kN from Ishii Loading Data)

FHWIND=(851 /D) X 1-m strip

=6.16 kN

4.3 Loading Diagram

5 Analysis and design

5.1 Check bearing pressure below ring beam

Consider 0.8-m thick ring beam.

ANET=( / 4) X (44.72 43.12)

=110.33 m2

Weight of Ring Beam (Consider 1.1-m deep)

WF=110.33 X 1.1 X 24 kN/m3

=2912.71 kN

Total weight acting on ring beam

Weight of steel shell:

WTS=5717 kN (From Ishii Iron Works. Refer to Sht 3 & 4 of Attachment 1)

Weight of liquid in contact with ring beam

WH2O=12437.14 kNW=WF + WTS + WH2O =21066.85 kN Actual Bearing Pressure

Qact=W / ANET=190.94 kPa, say 200 kPa

*Contractor to ensure that allowable bearing pressure at site is greater than 200 kPa. 5.2 Calculation of support springs (for Finite Element Model Analysis)

5.3 Calculation of support displacements loads (for Stick Model Analysis)

5.4 Analysis

Results were obtained using STAAD software.

See Attachment 4 for finite element analysis results and Attachment 5 for stick model Analysis results for verifying bottom reinforcements on ring beam.

5.5 Design

5.5.1 Required Reinforcement due to Ring Tension

Ring Tensile stress from STAAD, Fts= 3829.23 kN/m-height/m-thk (due to Ult. Loads)

Ring Tensile forceFt=3829.23 X 1.1m-height X 0.8-m thk

=3369.72 kN

Total ring reinforcement required,Asring=3369722.4/(fy/1.05) = 7691.76 mm2Distribute reinforcement at beam edges (dist. factors = say 1.70 for sides, 0.30 for top & bottom):

At each side, Asides

=(7691.76/4) x 1.70= 3269 mm2

Top (and bottom) reinf. At&b

=(7691.76/4) x 0.30= 576.88 mm25.5.2 Required Torsional Reinforcements

Governing Twisting Moment, Mxy, from STAAD = 141.32 kN-m/m-strip

Considering twisting moment causes torsion against the ring:

Mtor=141.32 X 1-m strip

=141.32 kN-m

Check torsional shear stress, Vt = (2 X Mtor)/ [width2 x (depth width/3)]

=(2 X 141.32x106) / [11002 x (1100-800/3)]

=0.28 N/mm2 < Vtmin = 0.4

No torsional reinforcements required

5.5.3 Required Bottom Reinforcement

Vertical Uniform Moment, Mz, from STAAD = 1262.29 kN-m

(Stick Model Analysis Attachment 5)

Consider clear cover = 75 mm; effective depth, d = 1100 75 12 mm ties T 32 /2 = 997

Bottom Reinforcement, Asbot=1262.29 X 108 / (0.95 X fy X 0.95 X d)

=3049.7128 mm2

Total required bottom reinfrocements due to ring tension + moment:

Astbot=576.88+ 3049.7128

=3626.59 mm25.5.4 Required Shear Reinforcements

Maximum Vertical Shear, Fy, from STAAD = 231.13 kN(Attachment 5)

Consider clear cover = 75 mm; effective depth, d = 1100 75 12mm ties T32 /2 = 997 mm

Design shear stressv=Vu / bvd

= 231130 / (800 X 997) = 0.29 N/mm2

Total Bottom Reinf. RequiredAstbot =3626.5928 mm2

100Astbot/bvd=100 X 3626.5928 / (800 X 997) = 0.45By interpolating values in Table 3.8 of BS8110 Part 1, vc = 0.49 N/mm2

Since 0.5vc < v < (vc + 0.4), provide minimum links. Try link spacing = 150

Sv reqd= Asv 0.95fyv / 0.4bv

=2 x 113 x 0.95 x 460 / (0.4 x 800)

=308.90 > 150, ok

Use T12 @ 150 links

6 Details

Check Reinforcements provided:

Bottom Reinforcements= 5 -T32 bars

=4021 mm2 > Astbot = 3626.59 mm2, ok.

Side Reinforcements

= 7 T 25 (ea face)

=3436 > Aedge + Asides = 3269 mm2, ok

Shear Links

=2 legs T12 @ 150 mm

=226 mm2 > Asvmin = 109.84 mm2, ok

Total Longitudinal Reinforcements=14 T25 + 10 T32 bars

=14915 mm2 > Astbot + 2xAsides = 10164.59 mm2Attachment 1-Loading Data from Ishii Iron Works

Attachment 2-Differential Settlement Information/Subgrade Reactions

Attachment 3-Numerical Model and Loading Diagram

Attachment 4-Finite Element Analysis of Ring Beam

Attachment 5-Stick Model Analysis of Ring Beam

EMBED AutoCAD.Drawing.15

EMBED Excel.Sheet.8

=RWidth 0.8 m

FyTS

FHEQ

FHWIND

Psur

Pactive

PHYDRO

EMBED AutoCAD.Drawing.15

=RHeight \# "0.0" 1.1 m

EMBED Excel.Sheet.8

FyH20

017 May 2006Issue for ApprovalMAHNDMH

revdatedescriptionauthorcheckedapproved

Client:Panorama Contracting & Engineering Services Ltd.

Project:HIDD Phase 3 Package T3

Title:Structural Calculations

(Ring Beam Foundation for Steel Tank at Musalla B. S.)

Order No: Document: 1131004Rev 0Sheet 1 of 3

Client:Panorama Contracting & Engineering Services Ltd.

Project:HIDD Phase 3 Package T3

Title:Structural Calculations

(Ring Beam Foundation for Steel Tank at Musalla B.S.)

Order:document: 1131004rev. 0Sheet: 5 of 19

_1209279376.xlsSheet1

Calculation of support displacement load per support joint

Assume support displacement load varying over a semi-circle

Maximum differential settlement, D=-65mm

No. of joint supports (half-cirumference)=69nos.

JointSettlement, D

(m)

1-0.06500

2-3-0.06312

4-150-0.06123

5-149-0.05935

6-148-0.05746

7-147-0.05558

8-146-0.05370

9-145-0.05181

10-144-0.04993

11-143-0.04804

12-142-0.04616

13-141-0.04428

14-140-0.04239

15-139-0.04051

16-138-0.03862

17-137-0.03674

18-136-0.03486

19-135-0.03297

20-134-0.03109

21-133-0.02920

22-132-0.02732

23-131-0.02543

24-130-0.02355

25-129-0.02167

26-128-0.01978

27-127-0.01790

28-126-0.01601

29-125-0.01413

30-124-0.01225

31-123-0.01036

32-122-0.00848

33-121-0.00659

34-120-0.00471

35-119-0.00283

36-118-0.00094

1 FY -0.065

2 3 FY -0.06312

4 150 FY -0.06123

5 149 FY -0.05935

6 148 FY -0.05746

7 147 FY -0.05558

8 146 FY -0.0537

9 145 FY -0.05181

10 144 FY -0.04993

11 143 FY -0.04804

12 142 FY -0.04616

13 141 FY -0.04428

14 140 FY -0.04239

15 139 FY -0.04051

16 138 FY -0.03862

17 137 FY -0.03674

18 136 FY -0.03486

19 135 FY -0.03297

20 134 FY -0.03109

21 133 FY -0.0292

22 132 FY -0.02732

23 131 FY -0.02543

24 130 FY -0.02355

25 129 FY -0.02167

26 128 FY -0.01978

27 127 FY -0.0179

28 126 FY -0.01601

29 125 FY -0.01413

30 124 FY -0.01225

31 123 FY -0.01036

32 122 FY -0.00848

33 121 FY -0.00659

34 120 FY -0.00471

35 119 FY -0.00283

36 118 FY -0.00094

0.00

0.00

0.00

_1209300983.dwg

_1209210140.dwg

_1209211146.xlsSheet1

Calculation of soil spring per support0.0009285714

Assume spring to be linearly varying

Soil Bearing Pressure, Q=200kN/m2

Maximum differential settlement, D=65mm

Width of ring beam, t=0.8m

No. of joint supports=138nos.

Element width in model, W=1m

Factor of safety, FS=1.5

JointSettlement, DSpring, KfyJointSettlement, DSpring, Kfy

(m)(m)

10.06503692.3137-1050.03257384.62

2-30.06413745.8238-1040.03167601.81

4-1380.06313800.9039-1030.03067832.17

5-1370.06223857.6340-1020.02978076.92

6-1360.06133916.0841-1010.02888337.47

7-1350.06043976.3342-1000.02798615.38

8-1340.05944038.4643-990.02698912.47

9-1330.05854102.5644-980.02609230.77

10-1320.05764168.7345-970.02519572.65

11-1310.05664237.0746-960.02419940.83

12-1300.05574307.6947-950.023210338.46

13-1290.05484380.7048-940.022310769.23

14-1280.05394456.2349-930.021411237.46

15-1270.05294534.4150-920.020411748.25

16-1260.05204615.3851-910.019512307.69

17-1250.05114699.3052-900.018612923.08

18-1240.05014786.3253-890.017613603.24

19-1230.04924876.6354-880.016714358.97

20-1220.04834970.4155-870.015815203.62

21-1210.04745067.8756-860.014916153.85

22-1200.04645169.2357-850.013917230.77

23-1190.04555274.7358-840.013018461.54

24-1180.04465384.6259-830.012119881.66

25-1170.04365499.1860-820.011121538.46

26-1160.04275618.7361-810.010223496.50

27-1150.04185743.5962-800.009325846.15

28-1140.04095874.1363-790.008428717.95

29-1130.03996010.7364-780.007432307.69

30-1120.03906153.8565-770.006536923.08

31-1110.03816303.9466-760.005643076.92

32-1100.03716461.5467-750.004651692.31

33-1090.03626627.2268-740.003764615.38

34-1080.03536801.6269-730.002886153.85

35-1070.03446985.4570-720.0019129230.77

36-1060.03347179.49710.0009258461.54

1 FIXED BUT MX MY MZ KFX 1846.155 KFY 3692.31 KFZ 1846.155

2 3 FIXED BUT MX MY MZ KFX 1872.91 KFY 3745.82 KFZ 1872.91




































































71 FIXED BUT MX MY MZ KFX 129230.77 KFY 258461.54 KFZ 129230.77

0.00

0.00

0.00

FIXED BUT MX MY MZ KFX 0 KFY KFZ 0



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design calculation for rc ring beam

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