Tutorial - Soil Overburden and Seismic Wave Propagation in AutoPIPE

8/9/2019 Tutorial - Soil Overburden and Seismic Wave Propagation in AutoPIPE

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

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

WORK FLOWASSIGNING SOIL PROPERTIES ...................................................................................................................... 4

NEW INPUTS IN AUTOPIPEV9.5 ...................................................................................................................................... 4

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

WORK FLOWSOIL OVERBURDEN LOADS .......................................................................................................................... 5

OPEN AUTOPIPEMODEL................................................................................................................................................ 6

SELECT A RANGE ............................................................................................................................................................ 7

SOIL PROPERTIES DIALOG ................................................................................................................................................ 8

EDIT SOIL PROPERTIES DIALOG ......................................................................................................................................... 9SOIL OVERBURDEN LOADS DIALOG .................................................................................................................................. 10

RUN ANALYSIS AND OPEN BURIED PIPE RESULT OPTIONS DIALOG ......................................................................................... 12

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

SEISMIC + THERMAL LOAD CASE .......................................................................................................................... 15

WORK FLOWSEISMIC THERMAL LOAD CASE .................................................................................................................. 15

OPEN AUTOPIPEMODEL.............................................................................................................................................. 16

SELECT A RANGE .......................................................................................................................................................... 17

SOIL PROPERTIES DIALOG .............................................................................................................................................. 18

EDIT SOIL PROPERTIES DIALOG ........................................................................................................................................ 19

SEISMIC WAVE DATA DIALOG ......................................................................................................................................... 20SEISMIC THERMAL LOAD ............................................................................................................................................... 21

RUN ANALYSIS AND OPEN BURIED PIPE RESULT OPTIONS DIALOG ......................................................................................... 22


BUILDING SETTLEMENT........................................................................................................................................ 24

WORK FLOWBUILDING SETTLEMENT ............................................................................................................................ 24

INSERT IMPOSED DISPLACEMENT .................................................................................................................................... 25


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ANALYZE MODEL AND ADD BUILDING SETTLEMENT ............................................................................................................ 25


ASME NC/NDADAMS ET. AL. STRESS SUMMARY .............................................................................................. 27

WORK FLOWASMENC/NDADAMS ET.AL.SUMMARY .................................................................................................. 27

OPEN AUTOPIPEMODEL.............................................................................................................................................. 28

SELECT A RANGE .......................................................................................................................................................... 28

SEISMIC THERMAL LOAD ............................................................................................................................................... 29

ANALYZE MODEL AND OPEN BURIED PIPE RESULT OPTIONS ................................................................................................ 30

CREATE ADAMS ET.AL.STRESS SUMMARY ........................................................................................................................ 30


MISCELLANEOUS INFORMATION ......................................................................................................................... 33

VIEW SOIL PROPERTIES ................................................................................................................................................. 33

LOAD COMBINATION DIALOG ......................................................................................................................................... 34

BURIED PIPE RESULT OPTIONS DIALOG ............................................................................................................................. 34

SOIL OVERBURDEN CATEGORIES ..................................................................................................................................... 35

SEISMIC +THERMAL CATEGORY ...................................................................................................................................... 35

BUILDING SETTLEMENT CATEGORY .................................................................................................................................. 35

SOIL OVERBURDEN STRESSES APPLICATION ON AUTOPIPEPIPING POINTS.............................................................................. 35

BUOYANCY FORCE EXERTED ON BURIED PIPING ................................................................................................................. 37

LIMITATIONS ............................................................................................................................................................... 37


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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.


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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 forcalculation 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


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Soil Overburden Loads

Work Flow Soil Overburden Loads

Open Existing AutoPIPE Model

Select pipe range for Soil

Properties

Open Soil Dialog (Insert > SoilProperties) 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


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Open AutoPIPE Model

Open Model SOILOVERBURDEN_1 .DAT


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Select a Range

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


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Soil Properties Dialog

Open Soil Propertiesdialog through Insert > Soil Properties. Define the Soil IDto APIP_H and

Maximum Spacing to the default 80 inches, and then click the Enter Soil Propertiesbutton.


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Edit Soil Properties Dialog

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

and for generating soil stiffness properties. 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: TransitionExample". Soil stiffness values can be generated by changing the Calculation Methodand

pressing the Generatecommand button. Click on the Generatebutton to fill out the k1, p1, and

k2 values, then click on the Soil Overburden Loadsbutton to open Soil Overburden Loads

dialog.


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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 Identifieris required to be selected so that user can refer to which pipe IDsare used

on the previous dialog Edit Soil Propertiesin 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 loaddepends on the Surface Live Load Typedropdown 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 Kband Deflection coefficient Kxare

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 theBuried Pipe

Result Optionsdialog. The Buried Pipe Result Optionsdialog must also be used to include the

Soil Overburden Loadsin code compliance of the output report.


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Change the Surface Live Load Typeto Airport-180k, and accept the defaults. The value for f

should now be 17432 psi. Click OK in the Edit Soil Propertiesdialog and Soil Propertiesdialog.


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Run Analysis and Open Buried Pipe Result Options dialog

Open theAnalysis Setsdialog (Load > Static Analysis Sets...) and enable Non Linearoption for

analysis set 1. Press OK on theAnalysis Setsdialog. A confirmation message will appear asking

to analyze the model. Press Yes on the Confirmdialog and press OKon theAnalyze Alldialog

that follows.

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

Options). Note the default values in the Soil Overburden Categoriessection 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 Input Parametersfrom the Edit Soil

Propertiesdialog are used.

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

code complianceso the results of the soil overburdening is displayed in the output.


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Generate Batch Report

Open Batch Reportdialog (Result > Output Report.). Include Code Complianceas a section

to review Circumferential Wall Bending Stress and Ring Buckling Pressure with allowable values

as per the options selected.

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

The file SOILOVERBURDEN_2.DAT contains the final result of this tutorial section.


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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


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Open AutoPIPE Model

Open Model SOILOVERBURDEN.DAT


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Select a Range

Select a range to apply to the Soil Overburden Loads


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Soil Properties Dialog

Open Soil Properties dialog through Insert > Soil Properties. Define a soil ID and Maximum

Spacing, and then click the Enter Soil Properties button.


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Edit Soil Properties dialog

Ensure that the values of the soil parameters are what is needed, and click on Seismic Wave

Data to open the Seismic Wave Data dialog.


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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.

The Pipe Identifieris required to be selected so that user can see quick check for specific pipes

on the previous dialog Edit Soil Propertiesin front of dT. When calculating the temperature

using the Generate Seismic Thermal Load Case, AutoPIPE automatically use required pipeproperties 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

temperatureis checked, both the strains are added for calculating temperature.


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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.

Check Assign seismic wave data above to all Soil Identifiers.

Seismic Thermal Load

To generate a seismic thermal load case, open the Generate Seismic Thermal Load Casedialog

through Load > Seismic Thermal Load. An existing thermal load case can be modified by

selecting the 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 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

temperatureis checked, both the strains are added for calculating temperature.


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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


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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 (preferably at a point

where the pipe enters a building) by going to Insert > Xtra Data > Imposed Support

Displacement.

Analyze Model and Add Building Settlement

Run the analysis including the user case selected for imposed support displacement in the

analysis set. Open the Buried Pipe Result Optionsdialog through Tools > Model Options >

Buried Pipe Result Options.In the Building Settlement Category section, select the preferred

user case and check the box below it.


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Generate Batch Report

Open Batch Reportdialog through Result > Output Report. Include Code Complianceas a

section to review Building Settlement combination.



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ASME NC/NDAdams 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 (Load >

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


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Open AutoPIPE Model

Open any existing ASME NC or ASME ND model:

Select a Range

Select a range to apply Soil Properties, Soil Overburden Loads and Seismic Data. Create a soil ID

APIP_V using the American Lifeline Alliance calculation method and keep all default values.

Click the Generatebutton to fill out the k1, p1, k2 and yield displacement columns.


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Seismic Thermal LoadGenerate a seismic thermal load case through Load > Seismic Thermal Loadif Seismic +

Thermal combinations are required to be reported in the Stress Summary.


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Analyze Model and Open Buried Pipe Result Options

Run the analysis on the model and open the Buried Pipe Result Optionsdialog through Tools >

Model Options > Buried Pipe Result Options. You will observe the fields which do not apply in

ASME NC/ND are disabled.

Create Adams et. al. Stress Summary

Open the Stress Summarydialog through Tools > Stress Summary.Create a new Stress

Summary by clicking the Newcommand button. Select the appropriate Service Level. Note that

the Service Level will not affect any of the Adams et. al. stress summary values. Select theBuried PipingasAdams et. al.. 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.


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Load Combination Dialog

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

Pipe Result Optionsdialog, the Code Combinationstab in the Load Combinationsdialog (Tools >

Combinations) will display the ring buckling as a combination.

Buried Pipe Result Options dialog

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


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Soil Overburden Categories

The first dropdown box the calculation method can be selected, which directly affects the

results produced. It also dictates which values in the Soil Overburden Loadsdialog 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 SoilProperties

dialog. Adding circular bending stress to Sustainedwill 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 casecheck 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 casedropdown box displays all available user cases that the building

settlement load can be applied. SeeAdd Building Settlementfor details.

Soil Overburden Stresses Application on AutoPIPE Piping PointsSoil 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:


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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

stress

calculations

Comments

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


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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 soiloverburden 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 pipein the Edit Soil Properties

dialog for buried piping. If the buoyancy forces acting on the pipe due to ground water in the

upward direction exceeds 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.

Limitations

Currently there is a limitation that only a single face will be displayed for secondary soil points

after a Tee point (in either the header or the branch direction) in Adams et. al. Stress Summary


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report for ASME NC/ND. This may result in displaying the lower stress from both the faces

(minus and plus) of the secondary soil point for Seismic + Thermal stress if the axial force on the

two faces of the secondary soil point differs.

As a workaround, you can insert a run point very close to the Tee point (in the header and

branch direction, depending on direction of the segment). By doing so, the secondary soil

points after the newly inserted run points will display both faces for the secondary soil points.

For example, consider the following scenario displayed below in A01 is a run point, followed by

A02 Tee point. Point A03 follows the tee point in the header direction, whereas B02 follows the

tee point in the branch direction.

You can insert a run point very close (an inch for example) to A02 on the leg A02-A03 to be able

to see both faces of the secondary soil points. Similarly, you can insert a run point very close toA02 on the leg A02 -B02 to be able to see both faces of secondary soil points. Your model will

look similar to the one shown below after insertion of addition points:

Tutorial - Soil Overburden and Seismic Wave Propagation in AutoPIPE

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