Tank Foundation Design Procedure

TANK FOUNDATION DESIGN PROCEDURE TANK FOUNDATION module, which is supported by AFES. 1. Tank Foundation Module The type of storage tanks normally encountered in refinery, petrochemical and other industrial plants have cylindrical shells, essentially flat bottoms, and either cone roofs or float roofs. Tank size may range from 10 to 200 feet in diameter with height from 16 to 56 feet.

AFES Modules Suggested conditions for Tank Foundation Type is as below.

Guideline and Recommendation for the design of Tank Foundations Tank Foundation Type

Earth Foundations with a Crushed stone Ringwall

Conditions to be considered

 

The subgrade has adequate bearing capacity and acceptable settlements When the anchorage is not necessary¶

Earth Foundations with a Concrete Ringwall





Large tanks, tanks with heavy or tall shells and self-supported roofs impose a substantial load on foundation under shell Can be used where high foundation uplift

Reinforced Concrete Slab



Pile supported foundation where soil bearing pressures are very low



The reinforced concrete slab is very recommendable when the level of the underground water is high



The foundation is very expensive

forced are encountered resulting form internal pressure or wind/seismic loading to Advantage

 

The most economical type of tank foundation Provides uniform support of the tank bottom by dissipating concentrated loads in a granular





pattern Disadvantage

 

Possible the uneven settlement which cause additive effort in the future Difficult to construct flat level plane of the



provide for anchorage Allows very good leveling of the periphery of the bottom and the shell which is positioned on it Can used in congested areas with space limitations Relatively high cost than the crushed stone ringwall foundation

bottom of the shell of the tank (⇒ Leveling Ring※) 

Catastrophic failure of the bottom is possible if a leak starts and washes out the underlying

Application (Design

support Large Diameter Tanks

Small Diameter Tanks

All Tanks

Basis to be applied) Table 1-1 Tank Foundation Design Guide

Notes ¶ Regions of low seismicity or in seismic areas where the tank diameter to height ratio is such that there is no uplift of the tank shell or small sloshing effect. The magnitude of lateral forces, overturning moments, and associated hydrodynamic mass be determined to assess their impact on tank shell and foundation design ※ A concrete leveling ring can be used under the tank shell in the gravel ring wall foundation. This leveling ring is 200mm deep by 300mm wide unreinforced concrete whose primary function is to provide a stable level base upon which the fabricator can build the tank shell wall. Additional advantages of the leveling ring are to distribute concentrated shell loads on to the gravel ring wall and minimize edge settlement under seismic condition

2. Tank Foundation Design Process

Start

Choose Project Create Structure Input Foundation Geometry (=Node Data)

Assign Foundation Module (=Foundation Type: Tank1 tTTank1)

Input Feature Data (=Footing, Pier Shape, Dimension)

Set Footing Bar, Pier Bar

IF Pile Foundation, Array Pile Data

Set Anchor Bolt/Box

Input Equipment Data Input Load Case/Combination

Structural Calculation sheets

Take Off Bill of Materials

END

Generate Construction Drawing

Generate 3D Modeling Data

3. ‘Tank Foundation Data’ Input

1. Click “New/Open Project” to generate Tank Foundation in ‘Toolbar icon’ Menu. Choose Project that you want to work on in “Project Dialog Window”. Ex) This is example of choosing “KCI_MKS” Project.

AFES Main GUI : Open/Select Project

2. Click “Create New Structure” Icon to input ‘Structure Name’ in ‘Toolbar Icon’ Menu. “Add : Input ‘Structure Name’ in ‘New Structure Name’ dialog, then “OK” command button.

Add New Structure

3. Click “Geometry Data” Icon in Toolbar Icon Menu, then you can see “Geometry : Foundation Location Plan (Node Data)” Dialog. Input the coordinates of ‘Tank Foundation’, then click “Add” command button. Input ‘Tank Foundation’, and click “Save” Command button. Note) Choose Foundation or Spread Row that you want to edit, then click “Delete” to delete Node. EX) Make a Node to locate ‘Tank Foundation’ by clicking ‘Add’. Input coordinates and click “Save” command button.

Input/modify Geometry Data

4. Click “Assign Foundation Grouping” Icon in Toolbar Icon Menu. The “Structure Group” Dialog as below is shown. There are four types of Foundation as below.

Type 1, Type 2, Type 3, Type 4 1, 3 Node uses Type 1(Footing : Circle) for Modeling. 2, 4 Nodes use Type 2(Footing : Octagon). 5 Node use Type 3(Circle Ring). 6 Node uses Type 4(Footing : Polygon Ring, Pier

Circle Ring Wall). a) Steps below is how to specify Type 1 Module for 1, 3 Nodes. 1. Click ”New” Command Button. 2. Input ‘Group Name’ in ‘Group Name Input Box’, then choose Group Type “Tank_1” in ‘Group Type Input Box’. 3. Choose Non Pile Fdn, or Pile Fdn. Based on Condition. 4 Click ‘Same Size’ button to apply same size and reinforced steel data for two different foundation. A standard foundation for input Data can be chosen in Combo Box. Choose Node to assign from ‘Using node list’, click ‘>’ button, and click ‘Save’ to set up Foundation Module.

b) Steps below are how to specify Type 2 Module for 2, 4 Nodes. The standard shape of Type 2 module is Octagonal and Pier is Circle Ring Wall. Note) Shape of Footing can be converted in ‘Feature Dialog Window’. Click ”New” Command Button. Input ‘Group Name’ in ‘Group Name Box’. Choose “Tank_1” for Group Type. Choose Non Pile Fdn, or Pile Fdn based on condition of Soil.

Choose Pile Foundation. Choose Node to assign from ‘Using node list’ Click “>” and “Save” to specify Foundation Module.

Assign Structure Group

c) Steps below are how to specify Type 3 Module for 5 Nodes. The standard shape of Type e module is Circle Ring Wall. Click ”New” Command Button. Input ‘Group Name’ in ‘Group Name Box’. Choose “Tank_1” for Group Type. Choose ‘Block foundation’, then Soil Condition is automatically chosen to

‘Non Pile Fdn’. This foundation does not support ‘Pile Foundation’. Click ‘Difference Size( Each Foundation)’ button to apply different size and reinforced steel data for two different foundation. Choose Node to assign from ‘Using node list’ Click “>” and “Save” to specify Foundation Module.

Assign Structure Group

d) Steps below are how to specify Type 4 Module for 6 Nodes. The standard shape of Type 4 module is Polygon Ring, and Circle Ring Wall for Pier. Note) Shape of Footing can be converted in ‘Feature Dialog Window’. Click ”New” Command Button. Input ‘Group Name’ in ‘Group Name Box’. Choose “Tank_1”

for Group Type. Choose ‘Non Pile Fdn’ based on Soil Condition. Foundation Module only supports Soil Foundation. Choose Node to assign from ‘Using node list’ Click “>” and “Save” to specify Foundation Module.

Assign Structure Group

5. Choose ‘TANK-FDN-01’ in Combo Box. Click “Feature Data (Dimension)” Icon in ‘Toolbar Icon Menu’, then ‘Feature Input Dialog’ as below is shown. Steps to specify Type 1 Module is as below.

Choose ‘Footing Tab’ in Dialog Box. Choose ‘Soil Name’. Check ‘Allowable Bearing Pressure’ of Soil Foundation using the information of Soil Name, which is input in Bearing Capacity of Soil Tab of “Setting of Constant Dialog”. This is Input Box when you want to design Footing by Element. (You do not need to choose currently.) Choose Footing Shape as a Circle. Input ‘Footing Diameter.’ Input Height of Footing. Input ‘Lean Concrete and Crushed Stone Thickness.’ Input ‘Soil Height’. (Standard of Footing Top: Upward +, Downward -) Input a projecting part of ‘Dimension of Lean Concrete and Crushed Stone’ to horizontal direction. (Standard of Footing Edge.) Click “Save” Command Button to save Data.

input Feature : Footing

Choose a ‘Pier Tab’ in Dialog Box. Choose Pier Shape as a Circle Ring.

Input ‘Pier Diameter.’ Input ‘Wall Thickness.’ Input ‘Pier Height.’ Input ‘Grout.’ Move the Pier with eccentricity by inputting in Offset X/Y Direction. Click “Save” Command Button to save Data.

Input Feature : Pier

6. Choose ‘TANK-FDN-02’ in Combo Box.

Click “Feature Data (Dimension)” Icon in ‘Toolbar Icon Menu’, then ‘Feature Input Dialog’ as below is shown. Steps to specify Type 2 Module is as below. Most of steps are same as Type 1, but choose Octagon Shape in ‘Footing Shape’ Combo Box. Click “Save” Command Button to save Data.

Input Feature : Footing

7. Choose ‘TANK-FDN-03’ in Combo Box. Click “Feature Data (Dimension)” Icon in ‘Toolbar Icon Menu’, then ‘Feature Input Dialog’ as below is shown. Steps to specify Type 3 Module is as below. Most of steps are same as Type 1. Click “Save” Command Button to save Data.

Input Feature : Footing

8. Choose ‘TANK-FDN-04’ in Combo Box. Click “Feature Data (Dimension)” Icon in ‘Toolbar Icon Menu’, then ‘Feature Input Dialog’ as below is shown. Steps to specify Type 4 Module is as below. Most of steps are same as Type 1, but choose Circle Ring Shape in ‘Footing Shape’ Combo Box. Click “Save” Command Button to save Data.

Input Feature : Footing

9. Choose Foundation in ‘Group Combo Box.’ Click “Feature Data (Dimension)” Icon in ‘Toolbar Icon Menu’, then ‘Reinforcement Input Dialog’ as below is shown. Choose ‘Footing Tab’ in ‘Input Box’. Choose one of the ‘Bar Array Types’ Input reinforcing bar information fitting to Bar Array Type. 1 &3 Bar Types can choose only the information of Bottom reinforcing bar. Choose size of Footing Top & Bottom reinforcing bar. You can choose either Number or Spacing Input.

Note) You can choose ‘Using Bar’ in Material and Unit Weight Tab of “Setting of Constant”. Bar DB that AFES can support is ASTM A615, KS D 3504, BS 4449, SAUDI ARABIAN, TS 708, ES 272-74, and TIS 2725. You can add BAR DB if you e-mail to [email protected],kr. Input ‘Footing Clear Cover’ in Clear Cover Tab of “Setting of Constant”. It applies to all chosen Foundation. Data inputted in ”Setting of Constant” are save in unit of Current Project.

Input Reinforcement Data

Choose Pier Tab in ‘Input Box’. Tie Array, Spiral Array (Tie Bar) is only used for PM Diagram Analysis of Pier. It does not apply to ‘Ring Wall Pier’. Choose ‘Top Tie Bar Size’, and input Spacing. Note) The Main Reinforcing bar due to Hoop Tension of Ring Wall is 10-D22 reinforcing bar. The Bar shape of Ring Wall Pier is . (Main bar is Side Bar.)

The shape of Side Bar is

.

Change Data of Pier, and click “Save” Command Button.

Input Reinforcement Data Input Information of reinforcing bar in Pier Tap for ‘Ring Wall Footing’.

Input Reinforcement Data

10. Choose Foundation to array Piles in ‘Combo Box’. ’Pile Data’ Icon in ‘Toolbar Icon’ is generated only when choosing ‘Pile Foundation’. Click “Pile Data” Icon in ‘Toolbar Icon Menu, then ‘Pile Array Form Dialog’ as below is shown. Choose ‘ Pile Name’ in Input Box. Check Allowable Pile Capacity of Pile Foundation using the information of Pile Name, which is input in Capacity of Pile Tab of “Setting of Constant Dialog” Click “View Group Reduction” box after inputting ‘Pile Data’, then you can check the overlap of ‘Pile to Pile’. Default Data is 1.5 x Pile Diameter from Footing Edge, and Pile to Pile is 2.5 x Pile Diameter. Default Data to check overlap can be changed in ‘Design/Auto Design/Set Parameters’ window. Click “Insert” Command button or “Generation (New)” command button to arrange Piles again.

Input Pile Data

Click ‘Generation (New)’ command button, then the picture below is shown. Choose Circle or Rectangular for Pile Array. Below is example of Circle Array. Decide how many Circles are needed to arrange Pile. Choose 3 Circle Arrays. Diameter of the first Pile Circle is 1200 mm. Arrange 3 piles with 60 Start Angle. Diameter of the second Pile Circle is 3000 mm. Arrange 6 piles with 30 Start Angle. Diameter of the third Pile Circle is 4000 mm. Arrange 10 piles with 120 Start Angle. Choose ‘Base Point’ when you arrange ‘Pile’. (Example of arranging Piles based on Footing Center.) Refer to the picture for more input information. Input ‘Pile Data’, and click “Save” Command Button.

Input Pile Data

Example below is display result using Pile “Generation (New)” Wizard. Data can be converted by clicking “Save” Command Button after changing X/Y Coordination and Arranged Dia. of Spread Sheet. Piles can be added by clicking “Insert”, “Generation (Add)” Command Button. Click “Delete” Command Button to delete piles.

Input Pile Data

11. Choose Foundation to input “Anchor Bolt/Box Data” in Combo Box. ‘Layout of Anchor Bolts’ Dialog is shown when clicking “Anchor Bolts/Box Data” Icon in Toolbar Icon Menu. “Layout of Anchor Bolts” is information for drawing. AFES program does not examine

‘Anchor Bolt’. Choose who is going to supply ‘Anchor Bolt’ in Bolt Data. Choose whether Anchor Bolt & Box uses Unified or Metric Units. Data in ‘Anchor Bolt Size ‘ is different depends on Units. Note) Anchor Bolt Type & Size can be converted by Anchor Bolt Tab Box of “Setting of Constants”. Input Bolt Size, Projection, and Bolt Length. You do not need to input Bolt Size, Projection, and Length Data if “Using Anchor Box” in Anchor Box is checked. Choose ‘Anchor Bolts Array Type’. (Rectangular, Circle Array) If you choose ‘Circle Array’, Input ‘Start Angle, Number of Anchor Bolt, and Anchor Bolt Circle Diameter’, and click “Draw” Command Button. To change ‘Anchor Bolt’ coordinates, change Spread Sheet and click “Save” Command Button. You can add Anchor Bolt by clicking ”Add” Command Button. If you add Anchor Bolt on Circle Array, it changes to ‘Rectangular Array’.

Input Anchor Bolt/Box Data To delete all ‘Anchor Bolt Data’ & input new data, choose ‘Anchor Bolts Array Type’, input Data, and click “Draw” Command Button.

12. Choose Foundation to input “Equipment Data” in Combo Box. Click “Equipment Data” Icon in Toolbar Icon, then “Equipment Assign” Dialog is shown. To input specific information of Equipment, you have to input ‘Equipment Name’ & Type. Choose Equipment Node in Spread Sheet, and input ‘Equipment Name’. Click ”Save” Command Button in Toolbar Icon, and assign Equipment to Large Storage Tank. Note) Tank1 Type assigns automatically the Equipment Type as ‘Large Storage Tank’. Click “delete’ to delete Assigned Equipment.

Input Equipment Data

Click “Input” Icon in Toolbar Icon Menu after ‘Equipment Assign’, the dialog below is shown. Chose ‘Equipment Type’. The shape of Tank is changed according to Type. Input ‘Equipment Diameter.’ Input Default Data as ‘Pier to Pier Center’ value in AFES. Input ‘Equipment Shell/ Insulation/Fire Proofing Thickness.’ Input an Equipment Height & Bottom Plate Height. Input Equipment Empty, Operation, and Test Weight.

Input ‘Internal Friction Angle’ of Soil. Input a Filling Material Name, Unit weight, and Thickness for Ring Wall. Note) Thickness1 + Thickness 2 of Ring Wall should be same as ‘Pier Height’. Input a Data for ‘Sump Pit’. To save Data, click “Save” button.

Input Equipment Data

13. Choose Foundation to input “Load Case/ Combination” in Combo Box. Click “Load Case/Combination” Icon in Toolbar Icon Menu, then “Loads & Combination” Dialog is shown. The default load cases for a tank foundation that AFES generates are as follows: a)

Operating

b) Empty(=Erection) c)

Test

d) X Wind e)

Y Wind

f)

X Earthquake

g) Y Earthquake

The default allowable or unfactored load combinations for a tank foundation generated by AFES depend on the concrete design code selected. For eg if ACI code is selected, the combinations are as follows: a)

DL + Oper

b) DL + Oper + X Wind c)

DL + Oper + Y Wind

d) DL + Oper + X EQ e)

DL + Oper + Y EQ

f)

DL + Empty(=Erec)

g) DL + Empty(=Erec) + X Wind h) DL + Empty(=Erec) + Y Wind i)

DL + Empty(=Erec) + X EQ

j)

DL + Empty(=Erec) + Y EQ

k) DL + Test

The default ultimate or factored load combinations for a tank1 foundation generated by AFES depend on the concrete design code selected. For eg if ACI 318 - 1999 is selected, the combinations are as follows: a) 1.4DL + 1.4Oper b) 1.05DL + 1.05Oper + 1.275 X Wind c) 0.9DL + 0.9Oper + 1.3 X Wind d) 1.05DL +1.05Oper + 1.275 Y Wind e) 0.9DL + 0.9Oper + 1.3 Y Wind f) 1.05DL + 1.05Oper + 1.403 X EQ g) 0.9DL + 0.9Oper + 1.43 X EQ h) 1.05DL + 1.05Oper + 1.403 Y EQ i) 0.9DL + 0.9Oper + 1.43 X EQ

j) 1.4DL + 1.4Empty(=Erec) k) 1.05DL + 1.05Empty(=Erec) + 1.275 X Wind l) 0.9DL + 0.9Empty(=Erec) + 1.3 X Wind m) 1.05DL + 1.05Empty(=Erec) + 1.275 Y Wind n) 0.9DL + 0.9Empty(=Erec) + 1.3 Y Wind o) 1.05DL + 1.05Empty(=Erec) + 1.403 X EQ p) 0.9DL + 0.9Empty(=Erec) + 1.43 X EQ q) 1.05DL + 1.05Empty(=Erec) + 1.403 Y EQ r) 0.9DL + 0.9Empty(=Erec) + 1.43 X EQ s) 1.0DL + Test

Note) 1. Input ‘Load Case Name & Load Case Value’ in ‘Load Case Window’, and make a ‘Load Combination’ in Load Combination Window. 2. Make ‘Load Combination’ using ‘Import Function’ in ‘Load Combination Window’, and go to ‘Load Case Window’, then ‘Load Case’ is automatically input. After following 1 or 2 steps above, input ‘Load Case Value’ for each pier. ‘Default Load Combination’ in AFES has the function that can design ‘Tank Foundation’ by importing “Vessel_Load_comb_1.txt” file in ‘Data Directory’.

‘Pier External Loading Sign Convention’ is as below. Axial Loads (Fz), Shear Loads (Fx, Fy), Moment(Mx, My, Mz) Axial Loads are negative downwards. Shear are positive if applied in the positive direction of X and Y Axis. Moments Mx are positive if applied in the counter-clockwise direction about the positive (+X) axis. Moments My are positive if applied in the clockwise direction about the positive (+Y) Axis.

Click “Load Case” Icon, then “Loads Case” Dialog is shown.

a) Choose Node to add Load Case. (EX. Choose Node 1, 3.) b) Choose ‘Unassigned Load Case’ in Show state of Load Case. c) Choose ‘Load Case’ in List Box, and click “Save” Command Button. d) To add more ‘Load Cases’, repeat step c). Added ‘Load Case’ is displayed in Spread. e) If you finish adding ‘Load Cases’, click “Finish” Command Button.

Input Load Case Data

f) To add Load Case, click “Edit node list”, choose “Unassigned Load Case” and ‘Load case’, then click “Save” Command Button. g) To delete ‘Load Case’, choose ‘Load Case’ and click “Remove” Command Button. h) To input ‘Load Case value’, choose Load Case and input values in Spread Sheet, then click “Save” Command Button. Note) SW : ‘Default Load Case’ of AFES is SELF WEIGHT. Fy (=-1) means that automatically calculate ‘Foundation Self Weight’ to the direction of Vertical Downward.

Click “Load Combination” Icon, then “Loads Combination” Dialog is shown. a) Click “New” Command Button. b) Input Load Combination “Name”. c) Choose Load Cases using Shift Key, then click “>” Command Button. d) Input Factor Value. e) Choose Elastic Strength(=Stability) or Ultimate Strength (=Reinforcement/Shear) Check for Load Combination. f) To use Safety Factor used for Sliding and Overturning Moment Check, choose Combo Box when it is for Stability Check. AFES can use 4 Safety Factor. Choose Factor for Allowable Increase in Combo Box. Note) Set up Sliding, Overturning, and Allowable Increase in “Setting of Constants”. g) Click “Save” Command Button to save the values. h) Repeat step a) ~ g).

4. Tank Foundation Design 1. Choose a ‘Foundation Group’. The steps for Foundation design is as follow. Click “Foundation Analysis/Design” Icon in Toolbar Menu, then “Analysis and Design” Dialog Window is shown as below. Choose ‘Regular Shaped Foundation Design Method (=Default)’, and click ”OK” Command Button.

2. There is a Dialog with several Design Methods. Detail of ‘Select Load Distribution Method’ is as follow. Choose whether External Load on Pier Top go to ‘Concentrated Force’ or ‘Uniform Load’. More specific explanation of ‘Shear & Reinforcement Design for MAT Module’ is as follow. Choose a ‘Critical Point ‘ to apply to Foundation based on ‘Building Code’. Choose a ‘Maximum Point’ to design Foundation with Allowance. It is a typical rule designing with ‘Maximum Value’ in Mat Foundation. Detail of ‘Structural Analysis Design of Foundation’ is as below. The Conventional Rigid Method 1 : Analyze Foundation with internal force caused y external force. The Conventional Rigid Method 2 : Analyze based on the fact that the sum of external force and internal force is 0. Click “Go to Diagram” Command Button to see SFD, BMD Diagram. Click “Go to Summary” Command Button to see Summary Sheet.

Example of clicking “Go to Diagram” Command Button is as below. SFD, BMD Diagram can be seen in case of Footing/Group/Load Combination. In case of Tank Foundation, you can input values in ‘Number of Moment Dist. Point’ to assume concentrated load as distributed load. Click “Next” Command Button to see Summary Sheet.

Choose Load Combination for Foundation Design. To draw several plans in ‘Layout Plan’, you can adjust using “Number of Match Point” Tab.

“Summary Sheets” of calculation sheet is as below. You can save as ‘PDF File Format’ in any

Directory. Click ”Show Detail Report” Command Button to see detailed calculation sheet.

Detailed calculation sheet is as below.

Print out Reports by clicking ‘Option’ Icon in Toolbar Menu.

Click ‘Design/Interactive Design/Ring Wall Design’ to design ‘Ring Wall.’

To design a ‘Ring Wall Pier’, choose Footing in ‘Footing List’ and Pier in Pier List’, then click “Calculation (One)” Command Button. ”Detail Report” Tab is activated, and Design Result of Ring Wall is displayed. Click “Calculation (All)” Command Button to design multiple Ring Wall. ”Detail Report” Tab is activated, and Design Result of Ring Wall is displayed.

5. Material Calculation for ‘Tank Foundation’ To calculate Materials for Foundation, click “Take Off Bill of Material” Icon in Toolbar Menu. Input Spec. for Material Calculation, and click “Calculation” button. To apply a same input Spec. to other Foundation, click “Save” Command Button.

Materials Report for Foundation is as below. It displays Data, Summary Table, Calculation BOM, and Calculation Rebar. Rebar, Net BOM, here does not consider ‘Bar Bending.’

6. Tank Foundation Drawing Generation

AFES interfaces directly with AutoCAD, and MicroStation to create a construction drawing. Click “Export DXF File” Icon in Toolbar Menu to generate construction drawing. Click ”Option” Command Button to adjust Parameters for Drawing Generation. Click “OK” Command Button to generate drawing.

Option for drawing generation is as below. Data changes for Sheet, Font, Layers, Entity, Drawing (=Bar Leader Type, Bar Bending Include or Not), Bar Bending (=Rebar DB) can be saved. You can choose a single rebar that you want to calculate for Bar Bending calculation. You can verify the adjusted value in ‘Standard Tab’ of drawing. Ex) If you use ‘#-‘, choose ‘ASTM A 615’ and adjust values. Click “OK” Command Button after finishing ‘set up.’

AFES provides the viewer below. AFES automatically save drawings in Directory/ DxfData/ Project No. ”Standard” Tab is the value used for construction drawing. ”Layout” Tab is plan drawing of foundation location The rest of Tabs are Foundation Detail Drawing.

7. 3D Modeling Data Refer to “PDS_PDMS_User_Manual_English.pdf” Manual for 3D Modeling Data generation. .