[Spherical Vessel Foundation Analysis and Design Guide]

PURPOSE This practice establishes guidelines and recommended procedures for the design of Spherical Vessel foundations using AFES(=Automatic Foundation Engineering System). AFES can design Spherical Vessel foundations as either soil- or pile-supported footings.

CONTENTS This practice comprises the following:

Create or Open New Project Setting Soil and Pile Parameters Creating New Structure Generating Geometric Data Exporting Load Combination Assign Foundation Grouping Editing footing sizes and other parameters Pier and Footing Reinforcement Set Pile Layout for Pile Foundations. Adding Tie-Girder Import Load Combination for various foundation groups Performing Design and Analysis functions. Quantity BOM(Bill of Material) function Construction Drawing Export 3D Modeling Data (PDMS, PDS Frame Work Plus)

There is a need to gather all necessary data from responsible disciplines such as load data of machine or equipment from Mechanical group, etc. before proceeding to modeling. You can input loads directly to AFES through the “Load Case/Combination” feature or import superstructure analysis result files for foundation analysis and design.

Below figures are foundation types commonly used for Spherical vessel equipment supports. Use : Spherical Vessel Foundation

Design data sample for equipment is shown below based from actual projects. This equipment is a Exchanger supported by rectangular shape foundation.

DESIGN DATA

Equipment Design Data

Footing Sketch Sheet

1. Create or Open New Project The first step is to enter project specific items. These items include general data, client data and Job data about a project. General data includes project No. Project Name, Client Name, Site Name, any more. The

client data includes your client manager name, e-mail, number of telephone and fax, address. Job data includes assigned engineer, supervisor, duration of project, project rate that values the program needs to use for the specific project.

The Project Number and Structure Name entered in Project Information will display as a menu header Note: General Data should be input. This data needs to use for the specific project.

To open the existing project, or create a new project, Click on the “New/Open Project” from Top toolbar menu

1.1 Create New Project

a) From “File” menu, select “New/Open Project”. A window dialogue will display as shown.

b) Select “New Project” option then click “OK” button. A window dialogue will display as shown.

c) Enter information then click “OK” button.

Or

1.2 Open Existing Project a) From “File” menu, select “New/Open Project”.

A window will display as shown.

b) Select “Open Existing Project”.

c) Select a project then click “OK” button.

2. Setting Soil and Pile Parameters. Setting of constants options include design information that AFES needs in order to design a foundation. This includes a number of parameters such as design code, safety factor, bearing capacity of soil, capacity of

pile, material and unit weight, clear cover, allowable increase of soil, allowable increase of pile, strength reduction factors, supports and anchor bolt options.

In case of New project, set all design parameters from the “Setting of Constant” form.

2.1 Set “Bearing Capacity of Soil” from the “Setting of Constant” command. a) Click “Setting of Constant” button. b) Select “Bearing Capacity of Soil” tab.

c) Enter name in the “Soil Bearing Capacity Name” text box. d) Enter “Soil Bearing Capacity (Qa)” value. e) Click “Save” button.

2.2 Set “Capacity of Pile” from the “Setting of Constant” button. a) Select “Capacity of Pile” tab.

b) Enter name in the “Pile Name” text box.

c) Select “Pile Type”. d) Select “Pile Shape”. e) Enter values for “Pile dimensions” f) Enter values for “Allowable Capacities”.

g) Enter values for “Elastic Modulus (Ep)” and “ Pile Area”. h) Click “Save” button.

3. Creating New Structure. Every input and output data can be saved in AFES Data Base according to projects, which provide work

efficiency in control over project information. An engineer is able to create a file for a new project, reuse data from projects conducted previously, or eliminate old and useless data for the user’s own sake. 3.1 Choose “Create New Structure” button.

“Add : New Structure Name” dialog window will appear. Input structure name, and then click on the “New” button.

4. Generating Geometric Data This function enables us create nodes and its coordinates. It can be set in circular or rectangular arrays for

regular layouts or irregular arrangement through input in the coordinate boxes. 4.1. Click “Geometric Data” from the top menu.

A window form will appear as shown.

4.2 Create node arrangement for first tank.

a) Click “Wizard (New)” button. b) Set and input parameters as shown below.

c) Click “Add” then “Close” buttons.

4.2 Create nodes arrangement for second tank.

a) Click “Wizard (New)” button. b) Set and input parameters as shown below.

c) Click “Add” then “Close” buttons.

4.3 Create nodes arrangement for third tank.

a) Click “Wizard (New)” button. b) Set and input parameters as shown below.

c) Click “Add” then “Close” buttons.

Node arrangement is shown below.

5. Exporting Load Combination. This function enables us to export load combination data that was saved in text file in AFES program. After exporting the file, it will be available for import in this program.

5.1. Export Load Combination before assigning group otherwise they will be deleted.

a) Click “Load Case/Combination” button.

b) Click “Load Combination” button. A warning message will appear as shown.

c) Click “OK” button. The Load Combination form will appear as shown.

d) Click “Export” button.

e) Choose directory to save file, assign file name then click “Save” button.

6. Assign Foundation Grouping. The Assign Foundation Grouping command is used for assigning group for models with multi-foundations. This is very important because it eliminates repetitions of commands. Foundations with the same load

combinations are recommended to join in one group. The available foundation types are as follows;

The foundation modules in red box shown in above figure are normally used for Spherical Vessel equipment.

At the end of this step, we will create the structure as shown below.

6.1 Click “Assign Foundation Grouping” button.

6.2 Assign group for nodes 1 to 8.

a) Click “New” button. b) Assign name from the “Group name” text box.

c) Select “Tank_2” from the “Group type”. d) Select “Non Pile fdn.” option.

e) Select “Different size (Each foundation)”. f) Select nodes 1 to 8 from the “Using node list” form. g) Click arrow pointing to the right. h) Click “Save” button.

6.3 Assign group for nodes 9 to 16.

a) Click “New” button. b) Assign name from the “Group name” text box.

c) Select “Tank_2” from the “Group type”. d) Select “Pile fdn.” option.

e) Select “Different size (Each foundation)”. f) Select nodes 9 to 16 from the “Using node list” form. g) Click arrow pointing to the right. h) Click “Save” button.

6.4 Assign group for nodes 17 to 24. a) Click “New” button.

b) Assign name from the “Group name” text box.

c) Select “Tank_2” from the “Group type”. d) Select “Non Pile fdn.” option. e) Select “Different size (Each foundation)”. f) Select nodes 17 to 24 from the “Using node list” form.

g) Click arrow pointing to the right. h) Click “Save” button.

7. Editing footing sizes and other parameters. The Feature Data (Dimension) command is used to define the dimensions and other parameters necessary for the foundation and piers.

Typically, the foundations for small spheres will be octagonal in shape, while larger spheres will be an annular or ring type foundation due to economics. Individual footings also may be used based on number and spacing of vessel columns.

Plan footing dimensions should be in even 2 inch(=50 mm) increments. The footing thickness shall be 12 inches(=300 mm) minimum and thickened in 4 inch(=100 mm) increments. Size for both footings should normally be the same.

It may be necessary to assume a trial size for the purpose of analysis. Pier sizes are determined from column base plate dimensions and minimum edge distances for anchor bolts. Footing sizes are estimated from the pier circle plus the width of the pier plus the desired edge distance.

The footing thickness should be adequate to ensure sufficient rigidity for distributing soil bearing pressures in a uniform manner. Preliminary footing thickness for a ring type foundation may be determined from the following criteria, using the largest of the conditions:

t = 1'−0" or

t = (x − b)/3 where:

t = Footing thickness, feet x = Maximum projected distance between adjacent pier centerlines, feet b = Width of concrete pier parallel with X, feet

7.1 Edit footing size of group “G1”. a) Select “G1” from the “Group” selection in top menu.

b) Click “Feature Data/Dimension” button. c) Choose “SUPT-01” in the “Soil Name” selection.

<Footing tab>

<Pier tab>

d) Enter values as shown in the “Feature” form for “Footing” and “Pier”. e) Click “Save” button. 7.2 Edit footing size of group “G2”.

a) Select “G2” from the “Group” selection in top menu.

b) Click “Feature Data/Dimension” button.

c) Choose “SUPT-02” in the “Spring Support Name” selection.

<Footing tab>

<Pier tab>

d) Enter values as shown in the “Feature” form for “Footing” and “Pier”. e) Click “Save” button. 7.3 Edit footing size of group “G3”.

a) Select “G3” from the “Group” selection in top menu.

b) Click “Feature Data/Dimension” button.

c) Choose “SUPT-01” in the “Soil Name” selection.

<Footing tab>

<Pier tab>

d) Enter values as shown in the “Feature” form for “Footing” and “Pier”. e) Click “Save” button.

8. Pier and Footing Reinforcement

The Reinforcement Data command is used to assign bar sizes and spacing for piers and footings.

Reinforcement bar sizes depend on the design code designated in the Setting of Constant command. Set of bar array options are available in the Footing option. The arrangement of footing bars are parallel to the X and Y axis except for Tank1 and Tank2 Ring type modules which are in radial and longitudinal directions. Below are our based from our company standards.

Minimum Pier Reinforcement Piers should be designed as cantilever beams with two layers of reinforcement. When the required

reinforcing approaches ρ max, investigate the pier as a column. Size and reinforcement for each pier should

normally be the same. Dowel splices are not required if the vertical pier reinforcing projection is less than 6 feet in height, or the rebar size in feet above the top of the footing. For cases that exceed this limit, use dowels with minimum projections required for tension splices in accordance with Building Code. Minimum

reinforcing for piers is #5 at 12 inches on each face with #4 ties at 12 inches. Place double ties at top of piers to protect anchor bolts. All ties should encircle the vertical reinforcement. Pier ties are not normally detailed as column ties. If longitudinal reinforcing is not required to resist vertical loads, as is normally the case, through ties are not required.

Size and reinforcement for both columns should normally be the same. Use dowels to transfer the column loads to the footings. Minimum dowel projection should be that required for a tension splice in accordance with Building Code.

Minimum Footing Reinforcement The minimum footing reinforcing will be #5 at 12 inches c/c top and bottom. To minimize tagging of rebar and simplify rebar placement, longitudinally curved reinforcing (annular bars) should be divided in groups of the same radius, as opposed to bending each annular bar to a unique radius. Typically, the rebar fabricator

and contractor installing the rebar can arrive at a satisfactory approach to this type of installation.

From the main tool bar, click the “Reinforcement data” button. Reinforcement data form will appear as shown in below figure.

8.1 Tank2 “Polygon Ring” Foundation

a) Set Array Type

Select from the array types of footing reinforcement layout. Different forms for single and double layer arrangement are presented.

b) Set “Footing” reinforcement arrangement.

Enter the values of footing re-bar as shown. c) Select ‘Pier’ tab and set parameters as shown below.

d) Select “Save” then “Close” button.

7.2 Tank2 “Circle Ring” Foundation

a) Set Array Type Select from the array types of footing reinforcement layout. Different forms for single and double layer arrangement are presented.

b) Set “Footing” reinforcement arrangement.

c) Select ‘Pier’ tab and enter the values of its re-bar as shown below.

d) Select “Save” then “Close” button.

Fore further discussions, refer to Help documents.

9. Set Pile Layout for Pile Foundations. The Pile Data command is used to layout and assign piles in the foundation. Regular pile arrangements are available for circular or rectangular arrays.

This function is activated only when the selected type is Pile fdn. in the Assign Foundation Grouping command. Define pile features first before proceeding to this function in the Setting of Constant command.

8.1 Set Pile Arrangement for foundation group “G2”. (Circular Array) a) Select “G2” from the “Group” selection” in top menu.

b) Click “Pile Data” command. c) Select “Array Wizard” tab. d) Select “Origin Point”. e) Select “PHC Pile_1” from the “Pile Name” selection.

f) Set “Circular” option. g) Enter “Star Angle”, “No.” and “Pile Circle Dia. (PCD)”. h) Click “Regenerate” button. i) Click “OK” button.

10. Adding Tie-Girder The Tie Girder Data command is used to layout tie girders between two supports. It can be positioned at any location from top of footing up to pedestal. Its reinforcement information can also be set from this feature.

10.1 Set Tie-Girder Arrangement for foundation group “G2”. a) Select “G2” from the “Group” selection” in top menu.

b) Click “Tie Girder Data” command.

d) From your mouse, select two supports from foundation group “G2” in the screen. A window message will appear as below.

e) Click “Add tie girder” message. f) Set the Tie Girder dimension and reinforcement as shown below.

g) Click “Save button. h) Repeat above procedure in creating tie girder for other supports. Different tie girder name

maybe assigned for each tie girder including its parameters.

11. Import Load Combination for various foundation groups. The Load Case/Combination command is used to define, add, edit or delete load cases and combinations.

Assigned load cases can be combined with factors in accordance with a few design methods and specifications. Mainly applied load combinations are Allowable Strength Load Combination and Ultimate Load Combination. Combinations by Allowable Strength Design are normally applied with 1.0 factored value.

The purpose of the combinations is to take into account soil bearing capacity, sliding, overturning, uplift check, and pile capacity check for a pile supported foundation.

Combinations referring to Ultimate Strength Design are used for footing reinforcement, pier design, one way shear check, and taking different factors for various cases. Below are load cases and load combinations usually used for vertical vessel footing based from ACI code.

Load cases definitions are also discussed for further information. These are also based from our actual projects.

DESIGN LOADS The following design loads shall be considered for design of the foundations.

VERTICAL LOADS

Empty Weight : Fabricated weight of vessel, plus the weight of internals, piping, insulation, and platforms, generally taken from the vessel drawing. Operating Weight: Empty weight plus weight of operating liquid or contents; generally taken from the vessel drawing.

Test Weight : Empty weight plus the weight of water required for hydrostatic test; generally taken from the vessel drawing. It should be determined if hydrostatic testing will actually be done in the field. Generally, it

is desired to design for test as unforeseen circumstances may occur. The above loads will be considered as Dead Loads when applying load factors.

HORIZONTAL LOADS

Wind Load Wind loads will be calculated by the Structural Engineer using vessel and platform drawings and the following criteria: • Spherical surface wind pressure on the projected area of the insulated vessel applied at the area centroid.

• Flat surface wind pressure on each platform horizontal area times a 0.5 factor applied at the height of each platform. Wind pressure will be varied with height in accordance with the job specifications. Wind load calculations shall conform with Company Engineering Guideline: Wind Load Calculations, for wind design considerations and procedures.

Wind loads calculated by hand methods will be compared to supplier provided load data. If the results compare favorably, the higher value will be used for foundation design. If the results do not compare favorably, resolve the discrepancy before proceeding.

Seismic Load Seismic design considerations and procedures shall be in accordance with job specifications and

DISTRIBUTION OF LOADS Vertical loads from dead weight are assumed equally distributed to each outer column. Vertical loads due to

overturning moments are assumed to be distributed to each column in proportion to the column distance from the neutral axis of the column group.

Horizontal loads (wind or seismic) will be distributed to the spheroid vessel columns by tension bracing

spanning between the columns. Both wind and seismic conditions shall be considered. For purposes of analysis, the sphere is assumed a rigid body with the applied horizontal external load being distributed to each braced panel in proportion to the stiffness of the panel in the direction of the applied load. The sum of the component panel shears parallel with the loading must be equal to the applied external load.

Panel Shear (Vp), the shear between columns which is transferred to the pedestals by the tension bracing, can be calculated as follows:

V p = 2 V x ( 2 cos α) / n where V = total horizontal force acting on the vessel and columns

n = number of columns α = angle between panel and direction of horizontal force

Load Combinations The following load combinations will be used in the foundation design: • Empty weight plus wind (or seismic) • Operating weight plus wind (or seismic) • Test weight plus reduced wind

Load Combinations shall be calculated in accordance with Job Specification. The weight of the foundation and of the soil on top of the foundation shall be included as dead load in all of these load combinations.

You can actually create new load combinations through the Load Combination button but in this example, we will use Import command.

a) Click Load Combination button. The Load Combination form will display as shown.

b) Click “Import” button. c) Access the load combination file then click “Open” button. A warning message will appear as shown.

d) Select appropriate button as explained in the warning message form. e) Click “Save” button.

Repeat same procedure for the other foundation groups.

12. Performing Design and Analysis functions. AFES executes Foundation Analysis and Design according to design standards widely accepted. It is assumed that all external forces are loaded at the center of the piers and the connection between the pier and

the footing is considered to be rigid enough to carry those forces. Strength, stability and sectional design of components of footing, pier, corbels and tie girders are properly examined. Either a ring foundation or individual footings may be used depending on the number of supporting columns

and column spacing. Individual footings are typically analyzed by hand. Ring type foundations may be analyzed by hand using simplified assumptions or by finite analysis methods. Several approaches for analysis of ring foundations using finite element analysis may be found in Foundation Analysis and Design or Analytical and Computer Methods in Foundation Engineering by Bowles. Finite element analysis may be

performed using computer programs designated as approved reference systems. Piers will be designed in accordance with recommended column design procedures outlined in Building Code. Shear lugs may be utilized at column bases to resist high shear forces, which in turn may allow the use

of smaller anchor bolts and column piers. The design codes of AFES support ACI318-99, 02, BS 8110, Korean, AIJ-WSD99, CP-65 and IS456(2000). 12.1 Click on the “Foundation Analysis/Design” button to be able to start analysis and design.

12.2 Select “Foundation Design New Version”.

12.3 Click “OK” button.

For through discussion on setting other functions such as General, Temperature and Shrinkage/Stability, Tank Design, Detail Report Option and Contents, you may refer to help menu.

12.4 Using “Conventional Rigid Method”. a) Select “Rigid Method Foundation Design” option.

b) Click “Analysis” button.

c) Click “Report” button. The calculation report will display as shown below.

13. Quantity BOM(=Bill of Materials) function BOM functions are used for estimate of earthworks including other related items such as excavation, backfill, disposal, concrete, lean concrete, crushed stone, grout, formworks, protection materials, anchor bolts and

steel reinforcements.

Options for BOM take off for active structure and all structures in a project is supported.

13.1 For Active Foundation structure.

a) From “Design” menu, select “Quantity (BOM) then “Take off BOM 3D”.

b) Set parameters from the “Afes – Bill of Material” form.

c) Click “OK” button.

The “Bill of Material” form will display as shown below.

13.2 For All Foundation structures.

a) From “Design” menu, select “Quantity (BOM) then “Take off BOM 3D (All Structure)”.

b) Set parameters from the “Afes – Bill of Material” form.

c) Click “OK” button. d) Check structures to include BOM Take off calculation from the form below.

e) Click “OK” button. The “Bill of Material” form will display as shown below.

14. Construction Drawing AFES is a completely integrated software package for automatically producing drawings of reinforcing details for foundations that have been analyzed and designed using AFES. AFES interfaces with AutoCAD

and MicroStation to create a construction drawing with bar-schedule.

The Export DXF File command is used to export the drawing files made from AFES to other programs such as AutoCAD and MicroStation. Standard drawings are already set up for various design codes.

The program will create the DWG or DXF file format and display a construction drawing through a viewer. The drawing report consists of the Standards, Layout and Drawing detail including plan and sections of foundation with reinforcement schedules. You can set from this command the drawing preferences to be

utilized before exporting to AutoCAD. a) Click “Export DXF File” button. A form will display as shown below.

b) Set options from this form. c) Click “OK” button.

Drawing details will display as below.

15. Export 3D Modeling Data (PDMS, PDS Frame Work Plus)

Today, plant design works involve many design parts, modeling objects from each part allows other parts to assess those object on their work process helping streamlining the work process through project completion.

A 3D foundation model of the objects designed by various design parts effectively communicates the geometric design data. Therefore automating the work process from design to 3D modeling forms an integral component of reducing overall project cost. With our design to modeling interface from AFES to Frameworks Plus, you will experience significant productivity.

15.1 Export to PDS

a) Click “Export PDS Data” button.

A dialogue form will display as shown.

b) Set Output unit and coordinate mapping options. c) Check “Send Model Data to PDS” option then click “OK” button.

15.2 Export to PDMS a) Click “Export PDMS Data” button.

A dialogue form will display as shown.

b) Set various parameters accordingly and click “OK” button. For further discussions, you may refer to Help PDF manuals.