tutorial - soil overburden and seismic wave propagation in autopipe v9_5

Description: Soil Overburden and Seismic Wave Propagation

Product: AutoPIPE

Version Number: V8i (v9.5)

Submitted By: JT

Revision: 0.0

Table of Contents

TABLE OF CONTENTS ........................................................................................................................................................ 1

ASSIGNING SOIL PROPERTIES TO BURIED PIPING .............................................................................................................. 3

INTRODUCTION ............................................................................................................................................................................ 3

FURTHER INFORMATION ................................................................................................................................................................ 3

WORK FLOW ASSIGNING SOIL PROPERTIES .................................................................................................................................... 4

NEW INPUTS IN AUTOPIPE V9.5 .................................................................................................................................................... 4

SOIL OVERBURDEN LOADS ............................................................................................................................................... 5

WORK FLOW SOIL OVERBURDEN LOADS ........................................................................................................................................ 5

OPEN AUTOPIPE MODEL .............................................................................................................................................................. 6

ADDING GAPS/FRICTION/SOIL ....................................................................................................................................................... 7

SELECT A RANGE .......................................................................................................................................................................... 8

SOIL PROPERTIES DIALOG .............................................................................................................................................................. 9

EDIT SOIL PROPERTIES DIALOG ..................................................................................................................................................... 10

SOIL OVERBURDEN LOADS DIALOG ................................................................................................................................................ 11

BURIED PIPE RESULT OPTIONS DIALOG ........................................................................................................................................... 13

GENERATE BATCH REPORT........................................................................................................................................................... 14

SEISMIC + THERMAL LOAD CASE ..................................................................................................................................... 16

WORK FLOW SEISMIC THERMAL LOAD CASE ................................................................................................................................ 16

OPEN AUTOPIPE MODEL ............................................................................................................................................................ 17

ADDING GAPS/FRICTION/SOIL ..................................................................................................................................................... 18

SELECT A RANGE ........................................................................................................................................................................ 19

SOIL PROPERTIES DIALOG ............................................................................................................................................................ 20

EDIT SOIL PROPERTIES DIALOG ...................................................................................................................................................... 21

SEISMIC WAVE DATA DIALOG ....................................................................................................................................................... 22

SEISMIC THERMAL LOAD ............................................................................................................................................................. 24

ADDING A SAM CASE ................................................................................................................................................................. 25


CODE COMBINATIONS ................................................................................................................................................................ 28


BUILDING SETTLEMENT .................................................................................................................................................. 31

WORK FLOW BUILDING SETTLEMENT .......................................................................................................................................... 31



INSERT IMPOSED DISPLACEMENT .................................................................................................................................................. 33

DEFINE LOADS AND RUN ANALYSIS ................................................................................................................................................ 35


CODE COMBINATIONS ................................................................................................................................................................ 37


ASME NC/ND ADAMS ET. AL. STRESS SUMMARY ......................................................................................................... 39

WORK FLOW ASME NC/ND ADAMS ET. AL. SUMMARY ................................................................................................................ 39



SELECT A RANGE ........................................................................................................................................................................ 42

APPLY SOIL LOADS ..................................................................................................................................................................... 43

ADDING A THERMAL LOAD CASE ................................................................................................................................................... 46

BURIED PIPE RESULT OPTIONS DIALOG .......................................................................................................................................... 47

COMBINATIONS DIALOG .............................................................................................................................................................. 48

CREATE ADAMS ET. AL. STRESS SUMMARY ...................................................................................................................................... 49


MISCELLANEOUS INFORMATION .................................................................................................................................... 51

VIEW SOIL PROPERTIES ............................................................................................................................................................... 51

LOAD COMBINATION DIALOG ....................................................................................................................................................... 52


SOIL OVERBURDEN CATEGORIES ................................................................................................................................................... 53

SEISMIC + THERMAL CATEGORY .................................................................................................................................................... 53

BUILDING SETTLEMENT CATEGORY ................................................................................................................................................ 54

SOIL OVERBURDEN STRESSES APPLICATION ON AUTOPIPE PIPING POINTS ............................................................................................ 54

BUOYANCY FORCE EXERTED ON BURIED PIPING ............................................................................................................................... 55

Assigning Soil Properties to Buried Piping

Introduction

The analysis of a buried piping system requires special modeling consideration. This is because the

restraint (support) provided by soil surrounding a buried pipe is continuous. As AutoPIPE analysis is

based on discretely defined points, so an accurate model of the soil's restraint capabilities would

require the definition of a number of closely spaced piping points. Each soil point would then require a

set of support springs which model the stiffness(es) provided by the soil at that point.

In AutoPIPE, user can select a range of pipeline and assign soil stiffness properties in four directions

and soil spring spacing for that range. Three sets of soil stiffness values can be assigned per soil

identifier, which enables the user to define a low bound, average, and high bound stiffness values. In

addition, AutoPIPE also has built in soil stiffness calculator, which automatically calculates soil stiffness

values based on soil properties entered by the user. Two methods for calculating the soil properties i.e.

AutoPIPE, and ASCE 2001 w/2005 addenda are provided. Moreover, A simplified tool for calculating

virtual anchor length has also been provided.

In AutoPIPE version 9.5, additional capabilities for calculating stresses in a buried piping due to the soil

load on top of pipe, soil overburden loads like traffic loads, ring buckling, effect of seismic wave

propagation, and building settlement effects. The workflows and additional information for calculating

these stresses has been detailed in this tutorial.

Further Information

For further information on how to insert soil properties to a pipe sections, refer to online help "Help >

Reference Information > PipeSOIL" and "Modeling Approaches > Example Systems > PIPE-SOIL

Interaction: Transition Example. You can always press the Help button on each dialog for specific

information.

Work Flow Assigning Soil Properties

New Inputs in AutoPIPE v9.5

In AutoPIPE version 9.5, a couple of new input parameters are added to the Soil Parameters input grid.

These are marked with an asterisk (*) to highlight that these inputs are required for calculation of

additional stresses only. Height of water on top of pipe is used for calculation of submerged soil weight

and buoyancy force exerted on pipe. Soil Adhesion is used in calculation of equivalent temperature dT

due to seismic wave propagation. Other additional inputs added in AutoPIPE version 9.5 will be

discussed in the sections below.

Create a new model or open

Existing AutoPIPE Model

Select pipe range for inserting

Soil Properties

Open Soil Properties dialog

(Insert > Soil Properties) and

click on Enter Soil Properties

Modify Soil input Parameters

on the Edit Soil Properties

dialog, and generate soil

stiffness values

Soil Overburden Loads

Work Flow Soil Overburden Loads

Open Existing AutoPIPE Model

Select pipe range for Soil

Properties

Open Soil Dialog (Insert > Soil

Properties) and generate soil

stiffness values

Open Edit Soil Properties dialog

and click on Soil Overburden

Loads

Analyze the model and open the

Buried Pipe Result Options (Tools >

Model Options > Buried Pipe

Results..." dialog to select options

related to Soil Overburden Categories

Generate batch output report

and review results

Add Non-Linear Option in the

Static Analysis dialog

Open AutoPIPE Model

Open Model SOILOVERBURDEN_1.DAT

Adding Gaps/Friction/Soil

In order to avoid any inconsistencies in the model, add Gaps/Friction/Soil by opening the Analysis Set

dialog (Load > Static Analysis) and modifying the first Analysis Set No.

Click OK on both windows, and when it asks if the analysis should be run, click No.

Note: Important to generate the seismic wave propagation thermal case before running the static

analysis

Select a Range

Select the range A04 N+ to A07. This will be used to apply the soil load.

Soil Properties Dialog

Open Soil Properties dialog through Insert > Soil Properties

Define the Soil ID to APIP_H and Maximum Spacing to the default 80 inches

Click the Enter Soil Properties button

Edit Soil Properties Dialog

For further explanation of how soil stiffness properties are generated, please refer to "Online Help >

Reference Information > PipeSOIL" and "Online Help > Modeling Approaches > Example Systems >

PIPE-SOIL Interaction: Transition Example". Soil stiffness values can be generated by changing the

Calculation Method and pressing the Generate command button.

Note the default Soil Parameters; these values will be used to apply the soil load to the piping

Click on the Generate button to fill out the k1, p1, and k2 values

Click on the Soil Overburden Loads button to open Soil Overburden Loads dialog

Soil Overburden Loads Dialog

All parameters need to be defined. Note that this dialog is only available for B31.1 (2004 or later) and

ASME NC/ND (2004 or later).

The Pipe Identifier is required to be selected so that user can refer to which pipe IDs are used on the

previous dialog Edit Soil Properties in front of f. When displaying the soil overburden stress f in the

output report, AutoPIPE automatically uses the required pipe properties at each point.

Pressure on pipe due to surface load depends on the Surface Live Load Type dropdown box, and can

be zero. Three surface load files (Highway-H20, Cooper-E80, and Airport-180) with pressure values at

different depths taken from ASCE 2001 are provided by default. Users can create custom live surface

load files by entering values of pressure on pipe due to external loads on different depths below

ground. The format of the file needs to be the same as the other "*.SLD" files shipped with AutoPIPE.

The Trench Laying conditions are taken from ANSI AWWA C150 and the values of Modulus of passive

soil fill reaction E', Bending moment coefficient Kb and Deflection coefficient Kx are defaulted to the

values for AWWA C150 when trench laying condition is changed.

The last four entries are dependent on which calculation method has been chosen. The default is

Adams et. al., however ASCE 2001 and AWWA C150 can be selected in the Buried Pipe Result

Options dialog. The Buried Pipe Result Options dialog must also be used to include the Soil Overburden

Loads in code compliance of the output report.

Change the Surface Live Load Type to Airport-180k

Accept the defaults by clicking OK

The value for f should now be 17431 psi. Click OK in the Edit Soil Properties dialog and Soil

Properties dialog.

Perform Analysis

Run the analysis (Analyze > Analyze All)

Buried Pipe Result Options dialog

Note the default values in the Soil Overburden Categories section of the dialog. The calculation

methods available are Adams et.al. AWWA C150 and ASCE 2001. The soil input parameters allow the

user to select what values of the Soil Parameters from the Edit Soil Properties dialog are used.

Open the Buried Pipe Result Options dialog (Tools > Model Options > Buried Pipe Result

Options)

Before accepting changes, be sure to check the Display circ. Wall bending & ring buckling in

code compliance so the results of the soil overburdening is displayed in the output

Generate Batch Report

Selecting Code Compliance allows the user to see the Circumferential Wall Bending Stress and Ring

Buckling Pressure with allowable value.

Open Batch Report dialog through Result > Output Report

Include Code Compliance as a section to review

Review the results at each point in the batch output report:

The file SOILOVERBURDEN_2.DAT is included and contains the final result of this.

Seismic + Thermal Load Case

Work Flow Seismic Thermal Load Case

Open Existing AutoPIPE Model

Generate seismic wave

propagation equivalent thermal

case(s) using the Generate

Seismic Thermal Load Case (Load

> Seismic Thermal Load)

Assign soil IDs to buried piping points

entering soil properties for each soil

ID and generate soil stiffness values

For each soil ID, also assign the

Seismic Wave Data using Seismic

Wave Data dialog.


Buried Pipe Result Options ("Tools >

Model Options > Buried Pipe

Results...") dialog to assign options

related to Seismic + Thermal

Categories

Generate the code compliance

report to see the seismic +

thermal stresses due to the

combined effect of seismic wave

propagation, seismic anchor

movement, and operating

temperature cases

Open AutoPIPE Model

Open Model SEISMICTHERMAL_1.DAT Note that for this model two thermal load cases have been

created.

1. A seismic wave propagation equivalent thermal case which will be combined with a SAM case

to give you the Seismic part in the Seismic + Thermal load combination

2. An operating thermal case which gives you the Thermal part in the Seismic + Thermal load

combination


In order to avoid any inconsistencies in the model, add Gaps/Friction/Soil by opening the Analysis Set

dialog (Load > Static Analysis) and modifying the first Analysis Set No.

Click OK on both windows, and when it asks if the analysis should be run, click No.


analysis

Select a Range

Select the range A04N to A07. This will be used to apply the soil load.

Soil Properties Dialog

Open Soil Properties dialog through Insert > Soil Properties

Define the Soil ID to APIP_H and Maximum Spacing to the default 80 inches


Edit Soil Properties dialog

Note the default Soil Parameters. These values will be used to apply the soil load to the piping. For

further explanation of how soil stiffness properties are generated, please refer to "Online Help >

Reference Information > PipeSOIL" and "Online Help > Modeling Approaches > Example Systems >

PIPE-SOIL Interaction: Transition Example". Soil stiffness values can be generated by changing the

Calculation Method and Soil Type and then pressing the Generate command button.

Leave the Calculation Method as default and click on the Generate button to fill out the k1, p1,

and k2 values

Check to see that the new values at the bottom of the dialog are the same as the image below

Click on the Seismic Wave Data button to open the Seismic Wave Data dialog

Seismic Wave Data dialog

All parameters need to be defined. Seismic wave type affects seismic wave coefficient aw and seismic

wave curvature coefficient ak. Note that this dialog is only available for B31.1 and ASME NC/ND years

2004 and higher.

Check Assign seismic wave data above to all Soil Identifiers

Click OK

Click Yes to confirm that you wish to apply this data to all soil identifiers

The value of dT on the Edit Soil Properties dialog should now read 72.507 deg F

Close both dialogs by clicking OK

The Pipe Identifier is required to be selected so that user can refer to which pipe IDs are used on the

previous dialog Edit Soil Properties in front of dT. When calculating the temperature using the

Generate Seismic Thermal Load Case, AutoPIPE automatically uses required pipe properties at each

point.

The strains generated in the pipe due to seismic wave propagation are calculated and using these

strain values, an equivalent temperature dT is calculated using coefficient of expansion for the material

. Ambient temperature is added to dT to reflect the effects of this temperature rise. This temperature

can then be added to a temperature case to simulate the effects of seismic wave propagation.

AutoPIPE calculates coefficient of expansion values based on expansion values of the material at

ambient temperature + 10 deg F. In case of non standard (NS) material, the expansion values are not

available from the library. In this case AutoPIPE uses the expansion value for steel taken as 6.5E-6

in/in/deg F.

AutoPIPE calculates both axial and bending strains due to wave propagation and takes the maximum of

two values. However, if the Add axial and bending strain for calculation of temperature is checked,

both the strains are added for calculating temperature.

If the Seismic data is the same for all soil IDs, you can define seismic data for one soil ID and use

"Assign seismic wave data above to all Soil Identifiers" option to set the same seismic data for all soil

identifiers. The final value for dT should be 72.507 deg F.

Seismic Thermal Load

An existing thermal load case can be modified by selecting it as Thermal load case to modify. AutoPIPE

will overwrite the temperatures at piping points for selected thermal load case with the calculated

seismic wave equivalent temperature depending on the different options on the dialog. This

temperature case can then be used in Seismic+Thermal category to be combined with the SAM case as

required by Adams method.

AutoPIPE calculates both axial and bending strains due to wave propagation and takes the maximum of

two values. However, if the Add axial and bending strain for calculation of temperature is checked,

both the strains are added for calculating temperature.

Open the Generate Seismic Thermal Load Case dialog through Load > Seismic Thermal Load

Click OK to accept the default values

The temperature change from this dialog is shown below.

Adding a SAM Case

Add a SAM case to the model.

Apply an Imposed Displacement (Insert > Xtra Data) of 5 inches in the Y direction on point A06

Set the Load case combine with to S1 and ensure that the Support Group No. is set to 1

Apply a SAM to the Support Group No. by opening the SAM / MSRS Support Group dialog

(Insert > SAM/MSRS Support Group)

Accept the default values

Finally, run the SAM Analysis (Analyze > Seismic Anchor Movement)

Perform Analysis



In order to activate the Display seismic + thermal combination in code compliance, both Thermal case

used for seismic wave propagation load and SAM case combined with seismic wave propagation

must have valid cases selected. Any SAM case that is available and analyzed can be selected as the

SAM case combined with seismic wave propagation. Select T1 and S1, respectively.

The Thermal case used for seismic wave propagation load should be selected as the temperature case

which has the equivalent seismic wave propagation temperature values assigned to it at each point.

Other operating thermal cases will then be automatically combined with these two load cases to

generate default combinations as per Adams method.

Open the Buried Pipe Result Options dialog (Tools > Model Options > Buried Pipe Result

Options)

Select T1 and S1 for Thermal case used for seismic wave propagation load and SAM case

combined with seismic wave propagation, respectively

Check Display seismic + thermal combination in code compliance and click OK

Code Combinations

Open the Load Combination dialog (Tools > Combinations). Click on the Code Comb. tab and ensure

that WavePR+SAM and Seismic + T2 are shown.

If Seismic + T2 does not show, open the Analysis Sets dialog (Load > Static Analysis Sets) and modify

the first Analysis Set No. to make sure that T2 is selected. If it is not, select it and re-run the Analysis

(Analyze > Analyze All). Recheck the Load Combination dialog to see the new combination.



Include Code Compliance as a section to review Seismic + Thermal combinations

Click OK to review the output report


The file SEISMICTHERMAL_2.DAT contains the final result of this tutorial.

Building Settlement

Work Flow Building Settlement

Create ASME B31.1-2010 model

and insert piping components

Insert Imposed Support

Displacement (Insert > Xtra Data >

Imposed Support Displacement...)


Buried Pipe Result Options (Tools

> Model Options > Buried Pipe

Results...") dialog to assign

options related to building

settlement

When the "Buil Sett" option in Buried

Pipe Result Options is checked then the

combination dialog will display the

additional category for ring buckling

Generate the code compliance report

to see the seismic + thermal stresses

due to the combined effect of seismic

wave propagation, seismic anchor


temperature cases

Open AutoPIPE Model

Open the BuildingSettlement_1.DAT model.


In order to avoid any inconsistencies in the model:

Add Gaps/Friction/Soil by opening the Analysis Set dialog (Load > Static Analysis) and

modifying the first Analysis Set No

Click OK on both dialogs

When it asks if the analysis should be run, click No


analysis

Insert Imposed Displacement

By inserting an imposed displacement as a user case, it is possible to display the building settlement

category in code compliance. Place an imposed displacement at A07 (should be the final anchor in the

model).

Open the Imposed Support Displacements dialog through Insert > Xtra Data > Imposed Support

Displacement.

Set Load case to combine with to U1

Set Y-translation to -5.0 inches

Click OK to close the dialog

Define Loads and Run Analysis

Open the Analysis Sets dialog (Load > Static Analysis Sets) and modify Analysis set No. 1 to

include U1 for analysis

Click OK and run the analysis


Open the Buried Pipe Result Options dialog through Tools > Model Options > Buried Pipe

Result Options

In the Building Settlement Category section, select user case 1

Check the Display building settlement category in code compliance box below it

Click OK to close the dialog and accept changes

Code Combinations

Open the Load Combinations dialog through Tools > Combinations

Note the Buil Sett U1{1} entry under the Code Comb. tab.

Click OK to close the dialog



Include Code Compliance as a section to review Building Settlement combination


The file BUILDINGSETTLEMENT_2.DAT contains the final result of this tutorial.

ASME NC/ND Adams et. al. Stress Summary

Work Flow ASME NC/ND Adams et. al. Summary

Create ASME NC/ND - 2007 model

and insert piping components

Assign soil IDs to buried piping

points entering soil properties for

each soil ID. Assign Soil

Overburden loads, and Seismic

Wave data. Also assign SAM

loading if required

Generate seismic wave

propagation equivalent thermal

case(s) using the Generate Seismic

Thermal Load Case (Tools >

Generate Seismic Thermal

Categories Case)

Generate the code compliance

report to see the seismic +

thermal stresses due to the

combined effect of seismic wave

propagation, seismic anchor


temperature cases

Open AutoPIPE Model

Open Model ADAMS_SUMMARY_1.DAT Note that there are two temperature load cases in this

model.


In order to avoid any inconsistencies in the model:

Add Gaps/Friction/Soil by opening the Analysis Set dialog (Load > Static Analysis) and modifying

the first Analysis Set No

Click OK on both windows, and when it asks if the analysis should be run, click No


analysis

Select a Range

Select the range A04 N+ to A07. This will be used to apply the soil load.

Apply Soil Loads

Open the Soil Properties dialog (Insert > Soil Properties)

Create a soil ID named APIP_H

Accept the default spacing of 80 inches


Note the default soil parameters

Click the Generate button

Then click the Soil Overburden Loads button

Change the Surface Live Load Type to Airport-180k

Click OK to close the dialog and accept the defaults

Click on the Seismic Wave Data button

Check the box Assign seismic wave data to all Soil Identifiers

Accept the defaults by clicking the OK button

Click the Yes button on the popup.

The Edit Soil Properties dialog should have the same f and dT values as seen below.

Accept the dialog changes and return to the model

Insert an imposed displacement (Insert > Xtra Data > Imposed Displacement)

Add a 5 inch displacement in the Y direction on Load case S1 and U1 to points A06 and A07,

respectively.

Apply a SAM case to the A06 point, by opening the SAM / MSRS Support Group (Insert >

SAM/MSRS Support Group)

Run the SAM analysis (Analyze > Seismic Anchor Movement)

Add U1 case to the analysis through the Static Analysis Load Cases dialog (Load > Static

Analysis) by modifying the first Analysis Set No.

Click No when AutoPIPE asks if you want to analyze the model

Adding a Thermal Load Case

Generate the thermal load case by opening the Generate Seismic Thermal Load Case (Load >

Seismic Thermal Load)

Check the Add axial and bending strain for calculation of temperature

Accept the other defaults by clicking OK

Notice the changes in the T1 load case in the Review Components Data dialog afterwards

Perform Analysis


Buried Pipe Result Options Dialog

Open the Buried Pipe Results Option dialog (Tools > Model Options > Buried Pipe Results

Options)

Notice that most of the fields do not apply in ASME NC/ND and are disabled

Update the fields as seen below and accept the changes.

Combinations dialog

Open the Load Combinations dialog through Tools > Combinations

Navigate to the User Allowable tab and notice the different combinations

Close the dialog by clicking OK.

Create Adams et. al. Stress Summary

Now you can select an operating thermal case, an equivalent seismic Thermal Case and a SAM load

case, which will all be combined to generate the Seismic + Thermal combination as per Adams et. al.

method. The Circumferential Wall Bending Stress and Ring Buckling pressure would be displayed for

each buried point automatically.

Open the Stress Summary dialog through Tools > Stress Summary

Create a new Stress Summary by clicking the New command button

Set the Service Level to C. Note that the Service Level will not affect any of the Adams et. al.

stress summary values

Select the Buried Piping as Adams et. al.

Set Thermal Load Case to T1, Seismic Thermal Case to T2, and SAM Load Case to S.A.M. 1

Make sure that the Print check box is selected, and click OK to accept changes.



Include Stress Summary" as a section to review Adams et. al. stress summary.


The file ADAMS_SUMMARY_2.DAT contains the final result of this tutorial.

Miscellaneous Information

View Soil Properties

After opening the Show Options dialog (View > Show Options), select the Soil Properties option

and click OK. AutoPIPE will prompt for a specific soil ID, or all of them. Select which one and accept.

AutoPIPE will display what pipe sections contain soil properties.

Load Combination Dialog

After ring buckling , seismic + thermal or building settlement case is enabled in the Buried Pipe

Result Options dialog, the Code Combinations tab in the Load Combinations dialog (Tools >

Combinations) will display the ring buckling as a combination.

The Adam method for NC/ND does not use the Code Comb. tab, but rather uses the Stress Summary

dialog (Tools > Stress Summary).


Here, you can change what soil overburden calculations are to be done, as well as seismic and thermal

category and building settlement category.

To open this dialog, go to Tools > Model Options > Buried Pipe Results Options

Soil Overburden Categories

The first dropdown box the calculation method can be selected, which includes Adams et.al, AWWA

C150 and ASCE 2001. This directly affects the results produced. It also dictates which values in the Soil

Overburden Loads dialog are used.

The next dropdown box is the set of data values required for calculation in soil overburden loads and

through wall bending stresses. These values can be seen in the Edit Soil Properties dialog. Adding

circular bending stress to Sustained will consider bending stress along with sustained stress. Ring

buckling allowable safety factor is applied to results as a factor of ring buckling allowable.

In order to include soil overburden load combinations in the output report, the Display checkboxes

must be checked (i.e. Display circ. Wall bending & ring buckling in code compliance)

Seismic + Thermal Category

The first dropdown is used to select which temperature case the seismic wave propagation load is to

be applied. A SAM case can also be applied, which, if both boxes are selected, allows the Display

seismic + thermal combinations in code case check box to enable. Seismic + thermal allowable safety

factor is applied to results as a factor of ring buckling allowable.

Building Settlement Category

Building settlement load case dropdown box displays all available user cases that the building

settlement load can be applied. See Add Building Settlement for details.

Soil Overburden Stresses Application on AutoPIPE Piping Points

Soil overburden stresses (circumferential wall bending stress, and ring buckling) are applied on all

intermediate soil points (i.e. +1, +2, etc.). An explanation of soil overburden stresses for AutoPIPE

piping points other than intermediate soil points is as below:

The model displayed above contains nine (09) piping control points and four soil IDs (SOILA, SOILB,

SOILC, and SOILD). The intermediate soil points are not displayed in the snapshot above, and these

intermediate soil points will always have soil overburden stresses defined based on the soil ID defined

for the preceding piping point.

The range on which each soil ID is assigned is highlighted with the legend displaying the color for each

soil ID. AutoPIPE B31.1 (2004 and onwards) and ASME NC/ND (2004 and onwards) will display soil

overburden stresses in code compliance report and Adams et. al. stress summary report based on

reporting and calculation methods selected.

The soil overburden stresses for different piping points and ranges will be displayed depending on

applicable soil ID as below:

Point / Range Soil ID used for soil overburden

Comments

stress calculations

A00 None

A01 to A02 N- SOILA Minus face of bend near point will display soil overburden stresses due to SOILA

A02 N+ to A02 F+

None

A03 SOILB All intermediate soil points following A03 will have soil overburden stresses based on SOILB

A04 to A05 N- None If there are no faces (minus, plus) for a piping run point, the second point will not have soil overburden stresses. This will assure a consistency if there is a different soil ID (say SOILX) defined on the range A04 to say A05 N-, in which case A04 will have soil overburden stresses due to SOILX.

A05 N+ to A05 F-

SOILC When there are two faces (minus, plus) on a piping point, the minus (-) face will calculate soil overburden stresses based on preceding point soil ID, and the plus (+) face will calculate soil overburden stresses based on current point (range) soil ID.

A05 F+ to A07 F- None A05 F+ will not have any soil overburden stresses

A07 F+ to A09 SOILD Last point in the segment will have stresses due to soil overburden based on preceding point soil ID.

Currently, AutoPIPE does not assign different faces to a piping point based on change in soil ID.

Buoyancy Force Exerted on Buried Piping

AutoPIPE requires user to input *Height of water on top of pipe in the Edit Soil Properties dialog for

buried piping. If the buoyancy forces acting on the pipe due to ground water in the upward direction

exceed the net downward forces of the pipe due to pipe weight, this force is reported in the model

input listing for soil. The pipe identifier used in this case is the pipe identifier last selected in the Soil

Overburden Loads dialog. If the net force acts in the downward direction, AutoPIPE reports the

buoyancy force on pipe as zero.

User may apply a net upward force due to buoyancy in AutoPIPE using the command Insert >

Distributed Loads.

tutorial - soil overburden and seismic wave propagation in autopipe v9_5

Documents

soil overburden loads

edit soil properties

autopipe v9

seismic thermal load

autopipe version number

open autopipe model

v8i v9

jt revision