[Heat Exchanger Foundation Analysis and Design Guide] PURPOSE This practice establishes guidelines and recommended procedures for the design of Exchanger, Heat Exchanger and Horizontal Drum foundations using AFES(=Automatic Foundation Engineering System). AFES can design Exchanger foundations as either soil- or pile-supported footings. CONTENTS This practice comprises the following:
z Create or Open New Project z Setting Soil and Pile Parameters. z z z z
Creating New Structure. Exporting Load Combination. Assign Foundation Grouping. Editing footing sizes and other parameters.
z z z z
Pier and Footing Reinforcement Set Pile Layout for Pile Foundations. Import Load Combination for various foundation groups. Performing Design and Analysis functions.
z Quantity BOM(Bill of Material) function z Construction Drawing z 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 Horizontal Vessel and Exchanger equipment supports. Use : Hex Foundation Modules
Design data sample for equipment is shown below based from actual projects. This equipment is a Exchanger and Horizontal Drum supported by rectangular shape foundation. DESIGN DATA Equipment Design Data
Footing Sketch Sheet
Sample spreadsheet calculation for wind and seismic load is presented below which was applied for actual project. This kind of calculation can be done by manual, excel, visual basic or in any form provided to satisfy code and standard requirements.
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. 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. 4.1. 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.
5. 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 Horizontal Vessel and Exchanger equipment. At the end of this step, we will create the structure as shown below.
5.1 Click “Geometric Data” button. 5.2 Create 8 nodes by clicking “Add” button 8 times.
5.3 Enter coordinates as shown in figure above.
5.4 Click “Assign Foundation Grouping” button.
5.5 Assign group for nodes 1 and 5. a) Click “New” button. b) Assign name from the “Group name” text box. c) Select “Heat_Excng” from the “Group type”. d) Select “Non Pile fdn.” option. e) Select “Same size”. f) Select nodes 1 and 5 from the “Using node list” form. g) Click arrow pointing to the right. h) Click “Save” button.
5.6 Assign group for nodes 2 and 6. a) Click “New” button. b) Assign name from the “Group name” text box. c) Select “Heat_Excng” from the “Group type”. d) Select “Non Pile fdn.” option. e) Select “Same size”. f) Select nodes 2 and 6 from the “Using node list” form. g) Click arrow pointing to the right. h) Click “Save” button.
5.7 Assign group for nodes 3 and 4. a) Click “New” button. b) Assign name from the “Group name” text box. c) Select “Heat_Excng” from the “Group type”. d) Select “Non Pile fdn.” option. e) Select “Same size”. f) Select nodes 3 and 4 from the “Using node list” form. g) Click arrow pointing to the right. h) Click “Save” button.
5.5 Assign group for nodes 7 and 8. a) Click “New” button. b) Assign name from the “Group name” text box. c) Select “Heat_Excng” from the “Group type”. d) Select “Non Pile fdn.” option. e) Select “Same size”. f) Select nodes 7 and 8 from the “Using node list” form. g) Click arrow pointing to the right. h) Click “Save” button.
The preliminary structure configuration is shown below.
6. Editing footing size and other parameters. The Feature Data (Dimension) command is used to define the dimensions and other parameters necessary for the foundation and piers. 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. The footing thickness adequate for embedment of pier or column reinforcement should be checked in accordance with Building Code. If top tension exists, the footing thickness shall be checked in accordance with Building Code. For thin footings with a large concentrated pier moment, the possibility of the moment increasing the punching shear should be considered similar to the way it would be for slabs (refer to Building Code). Engineering judgment should be used in deciding when this might be applicable. 6.1 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.
d) Enter values as shown in the “Feature” form for “Footing”. e) Click “Save” button. 6.2 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-01” in the “Soil Name” selection.
d) Enter values as shown in the “Feature” form for “Footing” and “Pier”. e) Click “Save” button. 6.3 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.
d) Enter values as shown in the “Feature” form for “Footing”. e) Select “T SUPPORT (RECTANGLE)” for pier shape. f) Enter values as shown in the “Feature” form for “Pier”. g) Click “Save” button. 6.4 Edit footing size of group “G4”. a) Select “G4” from the “Group” selection in top menu.
b) Click “Feature Data/Dimension” button. c) Choose “SUPT-01” in the “Soil Name” selection.
d) Enter values as shown in the “Feature” form for “Footing”. e) Select “T SUPPORT (RECTANGLE)” for pier shape. f) Enter values as shown in the “Feature” form for “Pier”. g) Click “Save” button.
7. Adding Tie-Girder The Tie-Girder Data command is used to add beams between two supports. It can be located to any point above the footing. The tie-girder dimension and reinforcement bar arrangements can also set in the dialogue window. 7.1 Add tie-girder between piers 2 and 6. a) Click Tie-Girder Data command button. b) From your mouse, select node 2 and node 6 then click “Add tie girder” message when it appears.
c) Set values in the form as shown in figure below then click Save button.
7.2 Add tie-girder between piers 4 and 8. a) Click Tie-Girder Data command button. b) From your mouse, select node 4 and node 8 then click “Add tie girder” message when it appears.
c) Set values in the form as shown in figure below then 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 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 amount of bottom reinforcing is #5 at 12 inches c/c. If top reinforcing is required, minimum reinforcing is #4 at 12 inches c/c.
From the main tool bar, click the “Reinforcement data” shown in below figure.
button. Reinforcement data form will appear as
8.1 Heat Exchanger Foundation with Rectangular Pier
a) Set Array Type Select from the array types of footing reinforcement layout. Different forms for single and double l ayer arrangement are presented.
b) Set “Footing” reinforcement arrangement.
c) Select “Save” then “Close” button. c) Select ‘Pier’ tab. Enter the values of footing re-bar as shown.
d) Select “Save” then “Close” button. 8.2 Heat Exchanger Footing with T-Shaped Pier
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. Enter the values of footing re-bar as shown.
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. 9.1 Set Pile Arrangement for foundation group “G3”. (Circular Array) a) Select “G3” from the “Group” selection in top menu. b) Click “Pile Data” command. c) Select “Array Wizard” tab. d) Select “Origin Point”. e) Select “PHC-12” 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.
Repeat above steps in creating new circular pile array arrangement then click “Add Draw” to include to
defined pile arrangement. 9.2 Set Pile Arrangement for foundation group “G4”. (Rectangular by Coordinates) a) Select “G4” from the “Group” selection in top menu.
b) Click “Pile Data” command. c) Select “Coordinates”. d) Select “Origin Point”. c) Select “PHC-12” from the “Pile Name” selection. d) Click “Add” button 8 times to create 8 piles. e) Enter coordinate values from the corresponding text boxes as shown. f) Click “OK” button.
10. 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 Horizontal Vessel and Exchanger footing based from Building 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. Erection Weight (De1) The erection weight is defined as the fabricated weight of the vessel, including internals and attachments that are installed integrally with the vessel. This information is taken from the vessel drawings. Verify that all items which are to be erected with the vessel are included in the erection weight. Empty Weight (De2) The empty weight is defined as the in-place weight of the completed exchanger/vessel (De1) plus the weight of internals, piping, insulation, and ladders and platforms, but excluding the weights of fluids or products which will be placed in the exchanger/vessel during operation. This information is taken from the vessel/exchanger drawings/data sheets and planning study drawings. Operating Weight (Do) The operating weight (also called "wet weight") is defined as the empty weight of the exchanger/vessel (De2) plus the weight of operating fluids or products. Verification of the operating conditions may be required from the Process Engineering Discipline. This information is taken from the vessel/exchanger drawings/data sheets.
Test Weight (Dt) The test weight is defined as the empty weight of the exchanger/vessel (De2) plus the weight of test fluid (usually water) and any attached piping and equipment required for the hydrostatic test. This information is taken from the vessel/exchanger drawings/data sheets. Note that this load condition is considered only when the exchanger/vessel is to be field-hydrotested. Verify with the Mechanical Discipline for this condition. Wind Loads (W) Transverse and longitudinal wind loads shall be determined in accordance with Design Guide 3DG-C01-00001 unless project criteria dictates otherwise. No allowance shall be made for shielding of wind loads by nearby equipment. The calculated design moments and shears due to wind load should be compared to those shown on the exchanger/vessel drawings. In case of major discrepancies between calculated wind loads and the loads shown on the equipment drawings, coordinate with the Mechanical Discipline for resolution. Seismic Loads (E) Seismic loads shall be determined in accordance with procedures presented in Company Design Guide unless project criteria dictates otherwise. The longitudinal seismic force shall be resisted by the fixed end pier only unless the piers are tied together by tie beams below the base plates. Transverse seismic forces shall be resisted by both piers using saddle or base plate reactions as the basis for computing base shear. The horizontal seismic loads shall be applied 100% in one direction and 30% in the orthogonal direction, i.e., E = ±(1.0 EH1 ± 0.3 EH2) and E = ±(0.3 EH1 ± 1.0 EH2). Thermal Load (T) The thermal load is defined as the load which results from thermal expansion or contraction of the exchanger/vessel in the longitudinal direction. The maximum thermal force is equal to the maximum static friction force (frictional resistance) acting at the equipment sliding support before the saddle begins to move. The frictional resistance equals the coefficient of friction times the vertical support reaction. The thermal load considered in foundation design shall be the smaller of the following: (a) The maximum pier reaction at the sliding end times the coefficient of friction of the sliding surfaces. (b) The force required to deflect each pier one-half the amount of the total thermal expansion between supports (assuming thermal loads of equal magnitude, but opposite directions, act on each pier). Generally, for short piers, the frictional force discussed in item (a) above governs the design. If it is impractical to provide for the thermal load in the cantilever pier design, a tie beam located below the vessel base plates may be utilized to resist the thermal load.
Bundle Pull Load (Lb) The bundle pull load is applicable only to foundations supporting exchangers with a removable tube bundle. It is the longitudinal force which results from the tube bundle removal operation during maintenance. This force shall be applied at the center of bundle elevation. In case of stacked exchangers, the more (most) critical load due to bundle pull, applied at the center of the respective bundle, shall be used. The force due to bundle pull shall be resisted by the fixed end pier only. Bundle pull load may be omitted if a bundle-pulling extractor is used for removal of the bundle. The method of bundle removal should be listed in the project design criteria. Unless the project design criteria dictates otherwise, the bundle pull load is considered to be 100% of the bundle weight. Bundle pull load should be considered as live load for assigning load factors. Piping Loads (Dp) Nozzle loads imposed by piping under operating conditions (including thermal effects on piping) shall be considered in the foundation design.
Coordinate with the Pipe Stress Group for determination of these
loads
LOAD COMBINATIONS Concrete Foundation Design The following factored load combinations should be used for design of the foundations
(a) 1.4 (Do + T + Dp) (b) 0.75 [1.4 De2 (or 1.4 De1)] ± 1.6 W (c) 1.2 De2 ± 1.0 E (d) 0.75 (1.4 Do + 1.4 T + 1.4 Dp) ± 1.6 W (e) 1.2 (Do + T + Dp) ± 1.0 E (f) 1.4 De2 + 1.7 Lb (for exchanger foundations only) (g) 1.2 Dt Both the longitudinal and transverse directional wind or earthquake loads should be included in the loading
combinations. The load factors shown above are based on ACI 318, except for load combinations (c) and (e), which are based on the slightly more conservative requirements of IBC 2000. Also, in load combination (g), the factor of 1.2 is used (instead of 1.4) due to the transient nature of hydrotesting conditions. The load combinations 0.9D ± (1.6W or 1.0E), as listed in ACI 318, do not need to be considered since they are covered by load combinations (b) and (c). Wind load is calculated in accordance with ASCE 7-98 (including the directionality factor) and seismic load is calculated in accordance with IBC 2000 (based on strength-level methods, rather than service-level). If wind load is calculated using another code which does not include the wind directionality factor, the load factors for wind in the various load combinations should be reduced appropriately. Similarly, for service-level seismic loads based on another code, the seismic load factors should be increased as appropriate. (See Section R9.2 of ACI 318 for guidance.) 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.
11. 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. The design codes of AFES support ACI318-99, 02, BS 8110, Korean, AIJ-WSD99, CP-65 and IS456(2000). 11.1 Click on the “Foundation Analysis/Design” button to be able to start analysis and design.
11.2 Select “Foundation Design New Version”. 11.3 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. 11.4 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.
12. 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. 12.1 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.
12.2 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.
13. 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.
14. 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. 14.1 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. 14.2 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.
