SAGE Profile V6.3.2 User Manual - Volume 2

SAGE Profile Version 6.3.2 User Manual

VOLUME 2

FINITE ELEMENT ANALYSIS MODULE Prepared By Fugro Engineers SA/NV Document Ref.: SAGE Profile V6.3.2 User Manual - Volume 2.doc Revision: 06 Date: 15/03/2005

Document Title:

SAGE Profile V6.3.2 - User Manual - Volume 2- 05 Finite Element Analysis Module

Document Ref.:

SAGE Profile V6.3.2 User Manual - Volume 2.doc

REVISION STATUS

Rev

Status

Compiled by DNC

Date March 1995

Reviewed by RW

date

Issued for comment

0.1

Issuedforcomment

TS

May1998

JWI

July1998

TST

Sept1998

0.2

UpdateforV6.1

JFW

May2002

HFA

May2002

JWI

May2002

0.3

Update for V6.2

MMA

Nov 2002

0.4

UpdateforV6.3

MMA

Sept2003

JWI

Nov2003

JWI

Nov2003

0.5

Update for V6.3.1

HFA

May2004

JWI

May 2004

0.6

UpdatedforV6.3.2

HFA

Mar2005

JWI

March2005 MMA HFA SSM JWI

AM

date

0.0

Signatory Legend:

March 1995

Approved by

March 1995

MatthieuM allié Hendrik Falepin Steven Smolders Jean-François Wintgens

Copyright © 1995 - 2005 Fugro Engineers SA/NV No warranty, expressed or implied is offered as to the accuracy of results from this program. The program should not be used for design unless caution is exercised in interpreting the results, and independent calculations are available to verify the general correctness of the results. Fugro Engineers SA/NV accept no responsibility for the results of the program and will not be deemed responsible for any liability arising from use of the program.

TABLE OF CONTENTS

TABLE OF CONTENTS

1. 1.1. 1.2.

1.3.

GENERAL DESCRIPTION ........................ ............................. ............................ ............... 5 Introduction ........................... ............................ ............................ ............................. ....... 5 PipeNet Overview ........................... ............................ ............................. ......................... 6 1.2.1. General ................................................................................................................... 6 1.2.2. 1.2.3.

Capabilities ............................................................................................................. 6 Pipeline Analysis Features ..................................................................................... 7

1.2.4. 1.2.5.

Program Assumptions ............................................................................................ 8 Code ....................................................................................................................... 8

1.2.6.

Flow Charts ............................................................................................................. 8

Running PipeNet ............................. ............................ ............................ ........................ 12 1.3.1. PipeNet DOS info window .................................................................................... 12 1.3.2.

2. 2.1.

DATAINPUT .......................... ............................ ............................ ............................. ..... 13 Introduction ........................... ............................ ............................ ............................. ..... 13

2.2. 2.3.

Data S tructure ............................ ............................ ............................ ............................. 14 List of Keywords ............................. ............................ ............................ ........................ 16

2.4.

Description of keywords .......................... ............................. ............................ ............. 17

2.5.

Example of Ty pical In put Fi les ........................... ............................ ............................ ... 53

3.

3

Using PipeNet in “Stand-Alone” Mode .................................................................. 12

DATAOUTPUT ........................... ............................ ............................ ............................. 60 3.1.

Introduction ........................... ............................ ............................ ............................. ..... 60

3.2.

Format of Stress Table File *.STR ........................... ............................ .......................... 61

3.3. 3.4. 3.5.

EXAMPLE OF STRESS TABLE OUTPUT *.STR ......................... ............................. ..... 63 Format of fu ll o utput fi le * .OUT .......................... ............................ ............................ ... 65 EXAMPLE OF 2D OUTPUT FILE *.OUT ............................ ............................ ................ 68

3.6.

Format of plot file *.PLO .......................... ............................. ............................ ............. 71

3.7.

EXAMPLE OF 2D PLOT FILE *.PLO ............................ ............................ ..................... 73

SAGEProfileV6.3.2-FiniteElementAnalysisModule

1.

GENERAL DESCRIPTION

GENERAL DESCRIPTION 1.1. Introduction SAGE Profile is a suite of programs for pipeline profile analysis developed by Fugro Engineers (formerly Thales Geosolutions). Operating with a standard Graphical User Interface (GUI) under Microsoft Windows, the suite enables the full range of pipeline profile analysis tasks to be performed efficiently. Volume 2 (this volume) of the set of documentation for SAGE Profile is concerned with the finite element analysis module PipeNet, forming the heart of the SAGE Profile system. Normally, the GUI will handle user interaction with PipeNet. This manual provides a user orientated description of PipeNet and describes the form of data input and output. The utilisation of SAGE Profile Interface is described in the User Manual Volume 1. The theory on which SAGE Profile is based is presented in SAGE Profile User Manual Volume 3. PipeNet has been subject to a rigorous Software Verification and Validation Plan following the IEEE Standard for software quality assurance. The Software Verification and Validation Document, including more than 60 test problems and solutions, forms part of the SAGE Profile documentation as Volume 4 of this series. SAGE Profile finite element engine PipeNet has been validated and certified by Bureau Veritas. Validation report and certificate are available on the SAGE Profile installation CD.

5


GENERAL DESCRIPTION

1.2. PipeNet Overview

1.2.1. General PipeNet is a finite element program for two- and three-dimensional pipeline stress analysis. Its capabilities include non-linear pipe bending, non-linear soil response (bearing capacity, and axial and lateral frictional resistance), large deformation analysis and buckling. General forms of loading include : self weight (including piggy-back lines), lay tension, loads (e.g. anodes),as distributed loads (e.g. displacements (e.g.point lifting during trenching) well as internal and current), external prescribed pressures and general temperature distributions. A schematic diagram depicting some of the programs 2D capabilities is shown in Figure 1.

Figure 1: Schematic showing some features of pipe2D.

Analyses are divided into loading stages corresponding to different stages in the life of the pipeline. Within each stage the loading is applied incrementally to follow the geometric and material non-linearities which may ensue. Thus, a typical pipeline analysis is defined by a laydown stage, followed by (for example) hydrotest loading in a second stage. A third operational stage could follow. In fact, an unlimited number of loading stages are possible with loading applied in any sequence following laydown. The theory on which PipeNet is based is described in the Volume 3 of the SAGE Profile User Manuals.

1.2.2. Capabilities 

Two- and three-dimensional analysis



Euler-Bernoulli beam-column elements



Variable pipe diameter and wall thickness



General specification of vertical, lateral, axial distributed loads (e.g. weight of pipe, current loads)


6

GENERAL DESCRIPTION



Point loads at arbitrary spacing and location



Prescribed displacements (local and global coordinates)



Arbitrarily or uniformly spaced field joints with reduced stiffness



Two non-linear pipe moment-curvature models (Moment-curvature defined by the Ramberg-Osgood curve or based on a uniaxial stress-strain curve)



General seabed profile including a cross-slope (3D)

 

General pipeline profile in plan (3D) Non-linear vertical, axial and lateral soil support



Modelling of column buckling (upheaval and snaking)



Pipe air filled or fluid filled, submerged or in air



Internal and external fluid pressures



General variation of temperature along pipe axis



General variation of initial tension along pipe axis



End fixity: free, rigid, pinned

  

Calculation of hoop stresses and true wall stresses Restart capability Output control and plot file

1.2.3. Pipeline Analysis Features Stress analysis of a pipeline in a finite element model requires special handling of the circular pipe cross-section if simple beam-column elements are used as in PipeNet. While the beam-column elements model satisfactorily the overall pipeline configuration, the analysis must handle the effects of internal and external fluid pressure on the stresses in the pipe wall as well as the thermal strains that can develop due to temperature effects. All of the most important features of circular pipe behaviour are included in PipeNet: 

Effect of internal and external pressure on the ends of the pipe



Hoop stress developed by internal and external pressure using formulae for thinwalled pipes.



Axial force developed in the pipe wall due to the Poisson’s effect of the hoop stress



Thermal strains and axial force in pipe wall due to temperature changes



Output of true wall stress and hoop stress for equivalent stress calculation

 



7

Lay tension may be specifically included Sag tensions are calculated automatically as a result of modelling geometric changes (large deformations) Moment-curvature relationship based on longitudinal stresses in the pipe wall and the uniaxial stress strain behaviour, accounting for the biaxial stress conditions in the pipe wall


GENERAL DESCRIPTION

1.2.4. Program Assumptions The principal assumptions existing in the present version of SAGE Profile are: 1) Non-linearities in the vertical soil support curves and in the explicit momentcurvature method are non-linear rather than plastic. Unloading results in the same non-linear relationship being followed. For axial soil springs and for the stress-strain based moment curvature model, unloading following plasticity is elastic. 2) The pipe is assumed to have zero diameter for seabed contact - the soil friction and support acts on the centreline of the pipe. 3) Soil supports are "lumped" at each node and act in translation only. Soil rotational stiffness is ignored. 4) For 3D analysis, the non-linearity in the pipe (Ramberg-Osgood model) is not history dependent. The single moment-curvature relationship is assumed to apply on the plane of maximum bending moment, irrespective of previous loading history (i.e. bending on other planes). 5) External water pressures are calculated based on the seabed elevation. This avoids continual updating of the loading at each loading increment when most depth variations are very small for profile analysis. 6) Pipe lay down is modelled by placing the pipe horizontally on the “highest hill” and applying the self-weight incrementally. This implies that the pipe weight is based on the KP length (i.e. the horizontal spacing between the KP points) and not the inclined length.

1.2.5. Code PipeNet is written in FORTRAN with the Digital Fortran compiler.

1.2.6. Flow Charts The data input algorithm is described in the form of a flow chart in Figure 2. The essential aspects of the analysis algorithm implemented in PipeNet are described in the flow charts given in Figure 3. Figure 4 describes the way the different non-linearities are activated from SAGE Profile Interface and how they are related to the control parameters available in PipeNet (see also 2.3).


8

GENERAL DESCRIPTION

Start

Set array parameters and default values

Open data input file

Start next load step

Null or reset load step arrays

No

Read from data input file until keyword encountered

Keyword "Analyse"?

Yes

EOF

Yes

Stop

Perform a load step analysis

No

Execute keyword to read data or control analysis

Figure 2: Data input flow chart.

9


GENERAL DESCRIPTION

Start load step analysis

Perform basic error checking Start load increment loop Set nominal load increment size for this increment Form elastic pipe stiffness matrix based on current geometry and

axial load

Add in ta ngent soil stiffness terms i f below gr ound Add in stif fness terms for prescribed d isplacemen ts Reduce equations Null all temporary vectors Start iteration loop for material non-linearity Form load vector for this increment including scale back Add in exce ss loads from m aterial no n-lineari ty from previo us iteration Solve for latest prediction of unknown

displacement s

Check for convergence - set convergence flag Check for new nodes touching and calculate fraction of load for first node to touch Scale back all incremental loads and deflections Calculate latest prediction of excess forces from soil non-linearity Calculate latest prediction of excess forces from pipe non-linearity

Convergence achieved?

No

Yes

Update displacements, actions and total applied load Perform system equllibrium check

No

Has 100% of load increment been applied? Yes Output load step results to file

Continue to read next keyword from input file

Figure 3: Analysis flow chart.


10

GENERAL DESCRIPTION

1.3. Running PipeNet

1.3.1. PipeNet DOS info window In run-time, a DOS window prompts the following information:

• Inc

the current load increment (counter).

• Tot load

the percentage of the total load applied to the model.

node number at which the maximum gap occurs between pipe • Node and seabed.

• Max Ds

maximum gap between the pipe and seabed.

If Scale Back is active, a number will appear showing a percentage of the load increment, which has been applied to conform to this criteria.

1.3.2. Using PipeNet in “Stand-Alone” Mode Due to changes in the software protection procedure, PipeNet of Version V6.1 and after can not run anymore in “stand-alone” mode.


12

DATA INPUT

2. DATA INPUT 2.1. Introduction This section consists of a guide to the data input file required by the PipeNet analysis program. SAGE Profile Interface actually creates the PipeNet input files (*.DAT file). This input file is editable in the Interface (see also SAGE Profile User Manual Volume 1). This chapter describes the commands used in the DAT file. The structure of the data input is first described generally, followed by a detailed description of the individual data items and options. An example of data input is provided at the end of the section. Further examples are available in the program validation section of the documentation.

13


DATA INPUT

2.2. Data Structure Keywords - Data is input using a series of KEYWORDS to define new data blocks and to instruct the program to perform particular operations. All data may be supplied in free format and may be in upper or lower case. Most keywords (i.e. data blocks) have a required number of parameters and, for some, a specific syntax must be adhered to. Keywords defining data may, in general, be provided in any order. The keyword defining material properties has a set of TOKENS which are used to define particular properties. Data sequence - Most pipeline analyses will be performed in a series of stages for which different data is required. For example, stage 1 may involve pipe lay, stage 2 hydrotest (new data required is the hydrotest pressure), stage 3 operational conditions (temperature and pressure to be defined). At each stage the input data may be provided for the first time, or even altered if necessary. The general order of data input will typically be: 1)

File header (not read by the program but identified by a "comment" character # in column 1)

2)

Project/run description to be echoed in the output

3)

List of KP versus seabed elevation values

4)

Definition of seabed and pipe characteristics

5)

Definition of restraints to the pipe (boundary conditions)

6) 7)

Pipe loading Analysis of this problem

8)

Additional/revised properties and loading

9)

Analysis of new problem etc

Figure 5 shows diagrammatically some of the basic keywords and how they are used to define the problem. Many examples of the use of the KEYWORD system are found in the validation manual (see Volume 4 of this series).


14

DATA INPUT

Figure 5: Diagram showing scope of some keywords.

Data input line types - There are four types of data input line according to the character in column 1:

Column1

Linecontents

*

Keyword

Blankordata < C, c, #, /

Normaldataline Name of file containing a partial or complete data set Comment line having no effect on the program

Entirely blank lines are also ignored. An exclamation mark (!) on a line will result in the characters to the right being ignored. This is to enable comments to be added. Each line is terminated by a carriage return (CR) character. Thus the last line in the data file must also terminate with a CR. 2D and 3D Analyses - When a 2D analysis is being performed, it is unnecessary to specify all parameters that would be required for a 3D analysis. All keywords are programmed such that parameters required by a 3D analysis follow those required for a 2D analysis. They only need to be present for the 3D case.

15


DATA INPUT

2.3. List of Keywords The list of allowable keywords given below is ordered alphabetically. Keywords in brackets [ ] are for program developers use only and should not be used by the general user. They are only included for completeness.  

*ALLOW_ANALYSE *ANALYSE

                            

*AXIAL_SPRINGS *CONTROL [*DANPLOT_2D] [*DANPLOT_3D] [*DEBUG] *ELEMENT_TYPES *GROUND_SLOPE *HORIZONTAL_PIPE *INHIBIT_ANALYSE *JOB_TITLES *KP_LIMITS *KP_VALUES *LH_RH_RESTRAINTS *LH_RH_SPRINGS *LOAD_STEP_TITLE *MAT_PROPS *NODAL_DISPS *NODAL_DISPS_LOCAL *NODAL_LOADS *NODAL_LOADS_LOCAL *NODAL_SPRINGS *NO_OUTPUT *PASS_THRU *RESTRAINTS *SPRING_CURVES *THREE_DIMENSIONAL *TWO_DIMENSIONAL *WRAP_INTO_3D *ZERO_AXIAL_DISPS


16

DATA INPUT

2.4. Description of keywords *ALLOW_ANALYSE Instructs the program to execute subsequent *ANALYSE statements. Used in conjunction with *INHIBIT_ANALYSE during a restart analysis while reading in the srcinal data input file. Parameters :

None

Example :

*JOB_TITLES A restart run from FIRST.DAT *INHIBIT_ANALYSE

! do not execute *analyse keywords in ! FIRST.DAT

!readinoriginalinputfile ! read in original restart file (results of original ! run)

*ALLOW_ANALYSE C New data *ANALYSE

Restrictions :

17

!solvethenewproblem

None


DATA INPUT

*ANALYSE Instructs the program to perform an analysis, i.e. solve the boundary value problem defined through the most recent set of keywords/data. Parameters :

None

Restrictions :

A problem must be defined sufficiently before *ANALYSE is invoked.


18

DATA INPUT

*AXIAL_SPRINGS Defines the parameters for the axial soil resistance curve for each axial curve type. The curve applies to the KP range defined in *NODAL_SPRINGS. Parameters :

Axial_curve_number

(-)

Displacement_to_yield

(m)

Adhesion

(kN/m)

Friction_factor

(-)

Format : Axial_curve_number Displacement_to_yield

Adhesion

Friction_factor

(repeat line for each axial_curve_type_numbers)

Example : *AXIAL_SPRINGS 1

0.004

2.3

0.6

!Curve/soil1-adhesionandfriction

2

0.003

0.0

0.5

!Curve/soil2-frictiononly

3

0.004

2.6

0.0

!Curve/soil3-adhesiononly

Restrictions :

19

None


DATA INPUT

*CONTROL Allows the user to alter the default program control parameters for a particular analysis or analysis stage. Parameters :

Control_parameter

(Integer)

Value

(Integer)

Format : Control_parameter

Value

(repeat as often as required)

Control_ parameter

Default value

Possible integer values

1

0

0

Donotinhibitoutputforagivenstage

1

Inhibit output for subsequent stages (same function as *NO_OUTPUT) Inhibit analyse (same as *INHIBIT_ANALYSE) Do not inhibit

Description

2

0

1 0

3

500

>0

Maximum number of iterations allowed to achieve convergence in a non-linear problem

4

3

>0

Convergencetolerance10

5-9 10

0

0 1 2 3

Not used Includes effect of axial force on element stiffness Ignore axial effect Ignore effect for compressive loads only Ignore effect for tensile loads only

11

-

-

Not used

12

50

>0

Number of nominal load increments (minimum number of steps to lay down the pipe or increment loads). Program will compute the actual size of the load increment to model lift-off and touchdown of the pipe accurately

13

1

>1

Defines number of elements into which the gap between seabed elevation values ( *KP_VALUES )

(-value).

Default 10-3

should be sub-divided. and KP points will be created New by pipe linearnodes interpolation between the existing KP’s. 14

16

4,8,16,32

15

-

-

Number of stress points around circumference of pipe (used in conjunction with option 18 6) for stress-strain based non-linearity Not used


20

DATA INPUT

Control_ parameter

Default value


16

1

1

Automatically calculates size of load step required for touch-down to be modelled accurately

0

Do not apply this load step size calculation

17

2

1

Soil non-linearity iteration: tangent stiffness plus "initial stress" iteration (i.e. Newton-Raphson)

2

No iteration: tangent stiffness method (i.e. Euler)

18

4

4

Pipe non-linearity iteration ( "initial stress" iteration)

0

No pipe non-linearity

6

Stress-strain based moment-curvature non-linearity using Ramberg-Osgood parameters set in *MAT_PROPS to define a material stress-strain curve

0

Do not apply equilibrium correction at each load increment

≠0

Apply equilibrium correction (Generally required-use not recommended)

0

Applypipenon-linearityinverticalplaneonly(2D)

1

Apply pipe non-linearity in horizontal plane only

2

Apply pipe non-linearity in both planes (normally required for 3D)

-1

Define soil springs in global axis directions (normal 2D case - no rotation during analysis)

3

Define soil springs in local pipe/soil direction (normal 3D case - rotated each increment)

1

Axialspringsloadplasticallyandunloadelastically

0

Axial springs behave non-linear elastic (loading/ unloading follow same curve)

0

Usestabilityfunctions

1

Do not use stability functions

19

20

21

22

23

24

0

2

-1

1

0

9999

>0

Description

not

Iteration limit for automatic reduction of load step size. Only used for iterative solution i.e. control 17 set to 1 (use not recommended)

25

26

21

1

-

0

Do not use under-relaxation for stiffening soil springs

1

Use under-relaxation with iterative solution i.e. control 17 set to 1. Not used for tangent solution

-

Not used


DATA INPUT

Control_ parameter

Default value


27

0

0

Usesynchronoustouch-downalgorithm

2

Use asynchronous touch-down algorithm

Description

28

1

1

Alternativestraincalculation

29

-

0 -

Axial strain for PIPE3_64 (now superseded) Not used

30

0

0

No calculation of forces associated with geometric non-linearity

1

Include full geometric non-linearity

Example : *CONTROL 12

1

! One load increment for elastic, non-touch-down problem.

18

0

! Switch off pipe plasticity.

3

2000

! Increase number of iterations to 2000.

Restrictions:

Should be specified at the beginning of the data input file if required to be applicable throughout the analysis, or before a new analysis stage is activated by *ANALYSE.

Notes:

Results accuracy can be enhanced by

• Increasing the number of increments (see control parameter 12).

• Refining the mesh (see control parameter 13). • Using the Newton-Raphson algorithm (see control parameters 17, 18, 24, 30)


22

DATA INPUT

*DANPLOT_2D, *DANPLOT_3D [Program developers use only] Creates a .PL file for use with DANPLOT plotting program

23

Parameters :

None

Restrictions :

None


DATA INPUT

*DEBUG [Program developers use only] Permits additional output for debugging purposes according to control parameters set on the following lines. Parameters :

Not publicly available

Restrictions :

None


24

DATA INPUT

*ELEMENT_TYPES Defines the element type number over a specific KP range. For each element type, a definition of pipe properties and loadings must appear in *MAT_PROPS Parameters :

KP_low

(m)

LowerendofKPrange.

KP_high

(m)

UpperendofKPrange.

Element_type_number

(-)

Number applying to this range.

Format : KP_low

KP_high

Element_type_number

(repeat as many times as required).

Default:

All elements default to type if not specified

Example: *ELEMENT_TYPES 0.0

1402

1

!type1 fromKP0.0-1.402km

1402

1950

2

!type2 fromKP1.402-1.950km

1950 3500

3500 4000

3 4

type ! 3 type ! 4

Restrictions :

25

(1)

KP ranges must correspond exactly to values defined under KP_VALUES.

(2)

Limited to 99 types.


DATA INPUT

*GROUND_SLOPE Permits definition of the ground slope in a direction perpendicular to the pipe axis (cross-slope) in 3D analyses only Parameters :

KP_low

(m)

LowerendofKPrange.

KP_high

(m)

UpperendofKPrange.

Ground_slope

(°)

Slope of ground

Ground slope is measured positive clockwise looking down the pipe axis in the direction of increasing KP.

Format : KP_low

KP_high

Ground_slope

(repeat as many times as required).

Default:

Ground slope is zero (horizontal)

Example: *GROUND_SLOPE 0.0

1402

0.0

no ! crossslope

1402

1450

2.0

!slope2°-slopingLtoR

1450

1480

5.0

slope ! 5°

1480

1550

3.0

slope ! 3°

1550

1580

-1.0

!slope-1°-slopingRtoL

Restrictions : (1)

KP ranges must correspond exactly to values defined under KP_VALUES.

(2)

Limited to slopes -90° < slope < 90°


26

DATA INPUT

*HORIZONTAL_PIPE Sets the initial position of the pipe to be horizontal and touching the highest point on the seabed. This keyword must be supplied when using the normal (horizontal) laydown method.

27

Parameters :

None

Restrictions :

Should appear once only before the first *ANALYSE keyword.

Notes:

This commands will implicitly define the initial pipe length (see also SAGE Profile User Manual Volume 3).


DATA INPUT

*INHIBIT_ANALYSE Instructs the program not to execute subsequent *ANALYSE statements. Used in conjunction with *ALLOW_ANALYSE during a restart analysis while reading in the srcinal data input file. Parameters :

None

Example : *JOB_TITLES A restart run from FIRST.DAT *INHIBIT_ANALYSE FIRST.DAT

! do not execute *analyse keywords in

!readinoriginalinputfile

! read in original restart file (results of original !

*ALLOW_ANALYSE C New data *ANALYSE

Restrictions :

!solvethenewproblem

None


28

DATA INPUT

*JOB_TITLES Reads in up to 10 lines of project information to be echoed in the output.

29

Parameters :

Up to 10 lines (up to 10 characters each) of alphanumeric text.

Restrictions :

A * must not appear in the first column of any line of text.


DATA INPUT

*KP_LIMITS Definition of lower and upper limits of the KP range to be analysed. These limits define the plan length of the pipe to be analysed and, if present, override any data outside the specified range from other keywords. Parameters :

Format :

KP_limit_low (m)

Lower limit of KP range.

KP_limit_high (m)

Upper limit of KP range.

KP_limit_low

KP_limit_high

Example: *KP_LIMITS 2500.

3500.

! Limit analysis of pipe to KP 2.5 - 3.5 km.

Restrictions : (1)

KP_LIMITS must be specified before KP_VALUES

(2)

KP_Values must cover the range of KP_Limits


30

DATA INPUT

*KP_VALUES Reads a set of KP's, associated seabed elevation values and X-Z plan co-ordinates (in 3D analyses). Normally, the KP data defines the nodal points of the finite element analysis and the undefined plan length of the pipe elements. Typical separation of points (i.e. element lengths) should be about 5m for reasonable touchdown and span prediction. Analysis time increases as the spacing decreases and probably can only be justified if seabed survey data is available. Parameters : KP_value

(m)

Seabed_Elevation

(m)

Measured relative to sea level specified by HSEA (Y-co-ordinate, +ve up, -ve downwards).

X-co-ordinate

(m)

Easting co-ordinate [3D only]

Z-co-ordinate

(m)

Northing co-ordinate (with reversed sign due to RH sign convention in PIPE) [3D only]

Format : KP_value

Seabed_Elevation

X

Z

(as many as required)

Notes :

1. X and Z are not required for a 2D analysis 2. The KP spacing, together with *HORIZONTAL PIPE keyword, defines automatically the spacing of the pipe mesh nodes (see also SAGE Profile User Manual Volume 3). 3. Automatic sub-division by linear interpolation can be performed by using control parameter 13 (see *CONTROL)

Example : *KP_VALUES 0.0

-151.0 12000. 666000.

5.0

-151.3 12005. 666000.

10.0 -152.8 12010. 666000. 11.0 -152.9 12011. 666000. 15.0 -153.1 12015. 666000.

Restrictions : (1)

31

Maximum number of KP values (nodes) is 2000. KP values must be in ascending order.


DATA INPUT

(2)

KP_Values must cover the range specified in KP_Limits if used

(3)

δKP must equal √(δX2 + δZ2) in a 3D analysis


32

DATA INPUT

*LH_RH_RESTRAINTS Permits the definition of the restraint conditions at the extreme left and right hand ends of the problem to be analysed (possibly defined by KP_LIMITS) in the global coordinate axis system. Parameters :

Fixity(x)

Free-1,fixed-0

Fixity(y)

Free-1,fixed-0

Fixity (xy) - rotation Fixity(z)

Free - 1, fixed - 0 Free-1,fixed-0[ 3Donly]

Fixity (xz) - rotation

Free - 1, fixed - 0 [3D only]

Fixity (yz) - rotation

Free - 1, fixed - 0 [3D only]

Format : Fix-X

Fix_Y

Fix_XY

Fix_Z

Fix_XZ

Fix_YZ

!forLHend

Fix-X

Fix_Y

Fix_XY

Fix_Z

Fix_XZ

Fix_YZ

!forRHend

Default :

All degrees of freedom assumed free (code 1).

Example : *LH_RH_RESTRAINTS 0 1 1 1 1 1

! LH end fixed in X only (axial for 2D problem)

1 1 0 1 1 1

! RH end rotation in XY plane fixed

Restrictions :

33

If the keyword *WRAP_TO_3D has been used, boundary conditions are automatically freed and the LH_RH_RESTRAINTS data block must be re-applied.


DATA INPUT

*LH_RH_SPRINGS Permits the definition of support springs at the extreme left and right hand ends of the problem to be analysed (possibly defined by KP_LIMITS). Parameters :

Stiffness (x)

Stiffness value in kN/m/m

Stiffness (y)


Stiffness (xy) - rotation

Stiffness value in kNm/rad/m

Stiffness (z)


Stiffness (xz) - rotation


Stiffness (yz) - rotation


Format : K-X

K_Y

K_XY

K_Z

K_XZ

K_YZ

!forLHend

K-X

K_Y

K_XY

K_Z

K_XZ

K_YZ

!forRHend

Default :


Example : *LH_RH_SPRINGS 0.0 0.1 0.1 ! LH end spring in Y and XY (Rotation) 0.0 0.1 0.1

Restrictions :

Note:

! RH end spring in Y and XY (Rotation)

None

Low stiffness springs are usually attached at both pipe ends (using LH_RH_SPRINGS) during the lay down phase in order to stabilise the solution. In case of very rough seabed, this may cause unexpected pipe lift off to take place at pipe extremities. Reducing the end springs stiffness should attenuate this phenomenon.


34

DATA INPUT

*LOAD_STEP_TITLE Reads in a single title line to be echoed in the output at the beginning of a new load step.

35

Parameters :

A single line (if up to 80 characters) of alphanumeric text.

Restrictions :

None


DATA INPUT

*MAT_PROPS Instructs program to read in the TOKENS which define pipe characteristics and loading for each element type as defined in *ELEMENT_TYPES. Values can be changed during analysis stages. Parameters :

These consist of "tokens" followed by an "=" sign and the value assigned, one token per line. Each element type group begins with the MAT= token, followed by the values for that group.

Format :

Token = Value.

Notes :

(1)

"Token" may be in upper, lower or mixed case. Spaces between the token and "=" are allowed. One token per line.

(2)

For the token MAT, a range of materials may be specified in a single line by (for example) : MAT = 01.04 where the "." refers to the range of materials 1,2,3,4.

Token MAT

Default

Units

Description

1

m

Identifies which element_type is referred to

DO

Mandatory

m

by the data which follows. ODofsteelpipesection.

TS

Mandatory

m

Wallthicknessofsteelpipe

2

AS

Calculated from DO,TS for circular section

M

Cross-sectional area of steel if default to be overridden

I

Calculated from DO,TS for circular section

m4

Second moment of area in pipe if default to be overridden

E

207E6

V

0.3

J

-

SY

ARO

1E99

0.0

kN/m2 -

Poissonsratioofsection.

m4 kN/m

Elastic modulus of section.

Torsional section modulus 2

-


Yield stress of steel (only used to establish nominal moment M0 in Ramberg-Osgood formulation, if M0 is not specified explicitly). Ramberg-Osgood parameter A defining the moment-curvature relation if CONTROL 18 = 4, or the uniaxial stress strain curve if CONTROL 18 = 6.

36

DATA INPUT

Token BRO

SIG_THRESH

Default 1.001

-

Units

Description

-

Ramberg-Osgood parameter B defining the moment-curvature relation if CONTROL 18 = 4, or the uniaxial stress strain curve if CONTROL 18 = 6.

kN/m2

Threshold stress below which non-linearity is assumed not to occur (for use with CONTROL 18 = 6). Note that defining a threshold which is exceeded during the course of the analysis can result in unstable results. The threshold should be set to well below the material yield stress (typically 0.5 * SY).

37

M0

0.0

kNm

Nominal moment used in definition of Ramberg-Osgood curve (Figure 2). Must appear after SY.

MP

1.0E99

kNm

Plastic moment for perfect-plasticity analysis (for verification only - effective if Control 18 is 1).

KT

0.0

/°C

BF

1.0

-

WSEA

0.0

kN/m3

HSEA

0.0

m

PI

0.0

kN/m2

DT

0.0

°C

Temperature change above or below ambient (increase +ve).

UDL

0.0

kN/m

Uniformly distributed load, such as pipe submerged weight (-ve downwards).

UDL-X

0.0

kN/m

Uniformly distributed load in global Xdirection on projected length of pipe (EastWest)- 3D only

UDL-Y

0.0

kN/m

Uniformly distributed load in global Ydirection on projected length of pipe (vertical) - 3D only

UDL-Z

0.0

kN/m

Uniformly distributed load in global Zdirection on projected length of pipe (NorthSouth) - 3D only

UDL-LX

0.0

kN/m

Uniformly distributed load in local X-direction (i.e. axial)

UDL-LY

0.0

kN/m

Uniformly distributed load in local Y-direction (i.e. vertical plane)

Coefficientofthermalexpansion. Bending factor used in calculation of equivalent stress. Unit weight of seawater. Height of sea level in global co-ordinate in system adapted for seabed elevation. Internal fluid pressure in the pipe.


DATA INPUT

Token

Default

Units

UDL-LZ

0.0

kN/m

TENS

0.0

kN

Description Uniformly distributed load in local Z-direction (i.e. horizontal plane) Residual pipetension(effective tension).

Example : *MAT_PROPS MAT=01.05 Do=0.5 Ts=0.010 HSEA=0.0 WSEA=10.075 MAT=1 apply. ARO = 0.8 12 BRO = 1800 M0 = UDL=-0.72 MAT=02.05 ARO = 0.8 BRO = 15 M0 = 2500

! Forelementtype1-5 ! Setdiaw/tsameforall ! elementtypes. ! SetHSEA,WSEAsameforall ! elementtypes. ! For element type 1 only the following ! ! ! ! Setweight0.72kN/m ! Forotherelements.

UDL = -0.68 Restrictions :

Mandatory parameters at least must be defined for all element types.

Notes : 1)

Material properties will be reassigned in successive appearances of tokens. The last appearance of a value before a *ANALYSE is the value adopted for that stage, and subsequent stages, unless it is changed.

2)

Loadings are cumulative when assigned in successive appearances of tokens in successive load steps (because the loading effect is retained in the element deformed configuration and stresses). Within the same load step, a token (e.g. UDL) will be overwritten by a subsequent one. Load definitions do not carry over from one load step to the next.

3)

In case of change in fluid content (for example, from Empty to Waterfilled), the water density WSEA is usually modified to take the variation in internal fluid density and its effect on the pipe internal pressure into account.


38

DATA INPUT

*NODAL_DISPS Reads in prescribed nodal displacements for any degree of freedom for the current load increment. In subsequent increments the node is free to move unless a new nodal displacement of greater than 1.0e-6 is applied. Parameters :

KP_value

(m)

Displacement_x

(m)

Displacement_y Rotation_xy

(m) (radians)

Displacement_z

(m)

[3Donly]

Rotation_xz

(radians)

[3Donly]

Rotation_yz

(radians)

[3Donly]

Format : KP_value

Disp_x

Disp_y

Rotat_xy

Disp_z

Rotat_xz

Rotat_yz


Example (2D): *NODAL_DISPS 5410.0

0.0

2.5

0.0

!Piperaised2.5mattwo

5425.0

0.0

2.5

0.0

!pointsseparatedby15m.

Example (3D): *NODAL_DISPS 5410.0

0.0

0.0

0.0

1.0

0.0

0.0

!Pipedisplacedlaterally

5425.0

0.0

0.0

0.0

1.0

0.0

0.0

!by1mat2points

Restrictions :

39

(1)

KP_values should coincide exactly with nodal co-ordinate values defined by *KP_VALUES keyword

(2)

Fixities should be specified using *RESTRAINTS or *LH_RH_RESTRAINTS not with *NODAL_DISPS using zeros (which are ignored).


DATA INPUT

*NODAL_DISPS_LOCAL Reads in prescribed nodal displacements for any degree of freedom for the current load increment in the current local pipe coordinate direction. In subsequent increments the node is free to move unless a new nodal displacement of greater than 1.0e-6 is applied. Parameters :

KP_value

(m)

Displacement_x

(m)

Displacement_y

(m)

Rotation_xy

(radians)

Displacement_z

(m)

[3Donly]

Rotation_xz

(radians)

[3Donly]

Rotation_yz

(radians)

[3Donly]

Format : KP_value

Disp_xD isp_y Rotat_xy

Disp_zR otat_xz

Rotat_yz


Example (2D): *NODAL_DISPS_LOCAL 5410.0 0.0 2.5

0.0

! Pipe moved upwards 2.5m at two points

5425.0

0.0

! plane in direction normal to the pipe.

! in the vertical 0.0

2.5

Example (3D): *NODAL_DISPS_LOCAL 5410.0

0.0

0.0

0.0

1.0

0.0

0.0

!Pipedisplacedlaterally

5425.0

0.0

0.0

0.0

1.0

0.0

0.0

!by1mat2points

Restrictions : (1)

KP_values should coincide exactly with nodal co-ordinate values defined by *KP_VALUES keyword

(2)

Fixities should be specified using *RESTRAINTS or *LH_RH_RESTRAINTS.


40

DATA INPUT

*NODAL_LOADS Reads in point loads for any degree of freedom (global coordinates) for the current load increment. Parameters :

KP_value

(m)

Force_x

(kN)

Force_y

(kN)

Moment_xy

(kNm)

Force_z

(kN)

Moment_xz

(kNm)

Moment_yz

(kNm)

Format : KP

Forc_x

Forc_y

Mom_xy

Forc_z

Mom_xz

Mom_yz


Example: (2D) *NODAL_LOADS 2155.0 3000.0

100.0 0.0 50.0 0.0

0.0 0.0

! Horizontal load of 100kN at kP2155. ! Horizontal load of 50kN at kP3000.

5000.0

0.0

-20.0

0.0

! Vertical load of 20kN.

100.0 -20.0

0.0

40.0

Example: (3D) *NODAL_LOADS 2155.0

0.0

0.0

!Loadof100kNinX! 20kN down in Y! 40 kN in Z-

Restrictions : KP_values should coincide exactly with nodal co-ordinate values defined by *KP_VALUES keyword.

41


DATA INPUT

*NODAL_LOADS_LOCAL Reads in point loads for any degree of freedom for the current load increment in local pipe direction. Parameters :

KP_value

(m)

Force_x(axial)

(kN)

Force_y(transverse)

(kN)

Moment_xy

(kNm)

Force_z (perpendicular to vert plane)

(kN)

Moment_xz

(kNm)

Moment_yz

(kNm)

Format : KP

Forc_x

Forc_y

Mom_xy

Forc_z

Mom_xz

Mom_yz


Example: (2D) *NODAL_LOADS_LOCAL 2155.0 3000.0

100.0 0.0 50.0 0.0

0.0 0.0

! Axial load of 100kN at kP2155. ! Axial load of 50kN at kP3000.

5000.0

0.0

0.0

! Transverse l load of 20kN.

0.0

40.0

-20.0

Example: (3D) *NODAL_LOADS_LOCAL 2155.0

100.0 -20.0

0.0

0.0

!Loadof100kNinx! 20kN down in y! 40 kN in z-

Restrictions : KP_values should coincide exactly with nodal co-ordinate values defined by *KP_VALUES keyword.


42

DATA INPUT

*NODAL_SPRINGS Defines the soil support type number over a specific KP range. For each soil support type (spring curve number) the characteristics of the curve are read in via *AXIAL_SPRINGS or *SPRING_CURVES (for "vertical" support). The direction of action of these springs depends on the setting of control parameter 21. By default these correspond to the global co-ordinate axes. If control parameter 21 is set to 3, the spring directions correspond to local pipe co-ordinate directions. Parameters : a] Global direction (always used for 2D analyses) KP_low

(m)

LowerendofKPrange.

KP_high

(m)

UpperendofKPrange.

Support_number (X-)

(-)

Translation (axial in 2D)

Support_number (Y-)

(-)

Translation (Vertical)

Support_number (XY-)

(-)

Rotational

Support_number (Z-)

(-)

Translation

Support_number (XZ-)

(-)

Rotational

Support_number (YZ-)

(-)

Rotational

(m)

LowerendofKPrange.

b] Local direction KP_low KP_high

(m)

UpperendofKPrange.

Support_number (X-)

(-)

Longitudinal (axial)

Support_number (Y-)

(-)

Perpendicular to pipe in vertical plane

Support_number (XY-)

(-)

Rotational in vertical plane

Support_number (Z-) slope (i.e. lateral)

(-)

Perpendicular t o p ipe, p arallel t o g round

Support_number (XZ-)

(-)

Rotational in XZ plane

Support_number (YZ-)

(-)

Rotational in YZ plane

Format : KP_low

KP_high

No_X

No_Y

No_XY

No_Z

No_XZ

No_YZ

Example : (Global and 2D)

43

0.0

1550.

1

2

0

0

0

0

! Axial no 1, vert. 2, no rotational spring.

1550.

2600.

3

4

0

0

0

0

! Axial no 3, vert. 4, no rotational spring.


DATA INPUT

Default :

All supports are assumed absent except the vertical which has a high default stiffness to represent "rigid" ground.

Restrictions :

A maximum of 99 springs can be defined. In 2D, a maximum of 33 KP ranges with different soil supports can thus be defined.


44

DATA INPUT

*NO_OUTPUT Instructs no output of nodal displacements or element values (moments, shears etc) to be output for a specific load step. Parameters :

None

Restrictions :

Should appear before the *ANALYSE command for which it is to apply.

45


DATA INPUT

*PASS_THRU Causes the next lines of data, up to the next keyword, be passed through to the output file without change Parameters :

None

Restrictions :

None


46

DATA INPUT

*RESTRAINTS Permits the definition of the restraint conditions in a specific range of pipe KP's to be set in the global co-ordinate axis system. Parameters :

KP_low

(m)

KP_high

(m)

LowerendofKPrange UpperendofKPrange

Fixity(x)

Free-1,Fixed-0

Fixity(y)

Free-1,Fixed-0

Fixity (xy) - rotation

Free - 1, Fixed - 0

Fixity(z)

Free-1,Fixed-0 [3Donly]

Fixity (xz) - rotation

Free - 1, Fixed - 0 [3D only]

Fixity (yz) - rotation

Free - 1, Fixed - 0 [3D only]

Format : KP_low

KP_high Fix_YZ

Fix-X

Fix_Y

Fix_XY

Fix_Z

Fix_XZ


Default :


Example : *RESTRAINTS 0.0

0.0

0

1

1

0

0

0

At !KP 0.0 K in X

1500.0

1600.0

1

1

0

0

0

0

!AtKP1500to ! KP 1600 K in XY

Restrictions : (1)

47

Restraints must be specified at KP values which coincide exactly with nodal coordinates defines by *KP_VALUES keyword.


DATA INPUT

*SPRING_CURVES Reads in the shape of the non-linear spring characterising the soil "vertical" support. One set of properties is specified for each "vertical" spring type number defined in *NODAL_SPRINGS. Parameters :

Note :

Vertical_support_number Number_of_points_on_curve

As defined in *NODAL_SPRINGS. (NP)

Deflection

(NP off)

Force_per_unit_length

(NPoff)

(m) (kN/m)

The force data provided will be multiplied by the appropriate element length by PIPE to give the spring force in kN corresponding to each deflection input. Thus the force to be input is the bearing pressure x the pipe overall diameter.

Format : Vertical_support_number

Number_of_points

Deflection(1)

Force(1)

Deflection(2)

Force(2)

: : Deflection(NP)

Force(NP)

(Repeat for next vertical_support_number)

Example : *SPRING_CURVES 1

4

!Springcurve1definedby4points

-1.0E99 0.0

0.0 0.0

! Zero stiffness above ground. !

0.5

50.0

!Initialstiffness100.0kN/m/m.

1.0E99 2

50.0 3

!Perfectlyplastic !Springcurve2definedby3points

-1.0E99 0.0

0.0 0.0

10.0

2000.0

Restrictions :

! Elastic-stiffness 200 kN/m/m.

Spring curve data must cover the entire range of deflections that could be encountered.


48

DATA INPUT

*THREE_DIMENSIONAL Instructs program to expect data for a 3D analysis and to perform such an analysis

49

Parameters :

None

Restrictions :

Must appear before any data other than control data is input


DATA INPUT

*TWO_DIMENSIONAL Instructs program to expect data for a 2D analysis and to perform such an analysis Parameters :

None

Restrictions :

Must appear before any data other than control data is input. Since the program default is 2D this keyword is not essential in the case of a 2D analysis. For a 3D analysis it is advised to switch back to 2D using this keyword during pipe laydown for execution speed.


50

DATA INPUT

*WRAP_INTO_3D Instructs the program to switch to 3D analysis taking into account induced moments in plan due to curvature of the pipe in the horizontal plane. This keyword is used after a two-dimensional ("straight") laydown has been completed in order to respect the actual three-dimensional position of the pipe in plan, allowing the pipe to move laterally on the seabed under the bending moments in the lateral plane and find its 3D equilibrium position.

51

Parameters :

None

Restrictions :

Should only be used once after the pipe laydown stage has been executed, and will normally be used in conjunction with setting up other 3D modelling parameters such as lateral soil resistances.


DATA INPUT

*ZERO_AXIAL_DISPS Instructs the program to zero any axial displacements which may have developed due to previous loading stages. In other words, the axial displacements vector is zeroed but the deformed pipe position is maintained. This is normally applied after the laydown analysis has been performed. It ensures that no “noisy” axial soil resistance due to axial movement during lay down is developed when the axial soil friction is activated. NB: this commands does not modify the pipe deformed shape. Parameters :

None

Restrictions :

Normally should appear just before a *ANALYSE keyword.


52

DATA INPUT

2.5. Example of Typical Input Files Two typical files for pipeline analysis are given below. Many other examples may be found in the “Software Quality Assurance Plan” Appendix D (Validation problems). ################################################################ # DEMONSTRATION DATA FILE FOR NORMAL 2D PIPELINE ANALYSIS # # Pipeline on an non linear foundation # # Data file prepared 20 November 1992, by D.Cathie # # Pipe data: # outside diameter = 0.50 m # thickness = 0.015 m # modulus of elasticity = 200e6 kN/m**2 # ################################################################ *JOB_TITLES Demonstration problem for a typical pipeline analysis on a flat seabed with non-linear properties *CONTROL 12

1

! only 1 load increment required for applying tension

#PROBLEM DEFINITION ################### *KP_VALUES # KP Depth 0.0 -100.0 5.0 -100.0 10.0 -100.0 15.0 -100.0 20.0 -100.0 25.0 -100.0 30.0 -100.0 35.0 -100.0 40.0 -100.0 45.0 -100.0 50.0 -100.0 *ELEMENT_TYPES 0.0 15.0 15.0 50.0 *RESTRAINTS 0.0 0.0 50.0 50.0

! seabed is flat for demonstration only

1 2 011 1 1 0

! Fixed axially ! symmetrical (no rotation)

*MAT_PROPS MAT Do Ts E V Kt WSEA HSEA M0 Aro Bro

53

= = = = = = = = = = =

01.02 0.5 0.015 200.E6 0.3 0.12e 4 10.075 0.0 1 0.0 1.0001

! same pipe material throughout

! nominal value is required (alternatively set SY) ! this produces an elastic R O relation


DATA INPUT

#DEFINE SEABED SOILS #################### *NODAL_SPRINGS 0.0 20.0 02.0 30.0 0 30.0 50.0

0

1 2

0

*SPRING_CURVES 1 3 -1.0E99 0.0 0.0 0.0 10.0 1.0e8 2 4 1.0-E99 0.0 .00 0.0 0.5 50.0 1.e99 50.0 3 4 -1.0E99 0.0 0.0 0.0 0.5 10.0 10.0 12.0

0

! Only vertical springs during laydown

0 3

0

!stiffelastic

! elastic-perfectly plastic

!bilinearelastic

#LOAD DEFINITION ################ *NODAL_LOADS 20.0 30.0 0.0 0.0 50.0 4 0.0 0 .0 0 .0

! axial tension KP 0 ! axial tension KP 20

20 is 70kN 40 is 40kN

*LOAD_STEP_TITLE Apply lay tension *ANALYSE ! solve for tension ######################################################## *CONTROL 12 20 18 4 *MAT_PROPS MAT = 01.02 UDL = -0.8 *HORIZONTAL_PIPE *ZERO_AXIAL_DISPS

! reset nominal load increments to 20 ! force pipe to be elastic ! uniform pipe self

weight 0.8 kN/m

*LOAD_STEP_TITLE Laydown case with pipe empty *ANALYSE !solve laydown problem without friction ################################################################ *NODAL_SPRINGS 00 .. 00 2 30.0

20 0. .0 0 3 50.0

4 5 6

1 2 3

0 0 0

*AXIAL_SPRINGS 4 0.004 0.0 0.5 5 0.003 0.6 0.0 6 0.004 50. 0.0 demonstrate ! effect on pipe stresses


! nvoewrp ti ip ce alisao nn d sheoarbiezdontal springs !

! define (axial) springs 4 and 5 ! artificially high stiffness to

54

DATA INPUT

*MAT_PROPS MAT = 01.02 UDL = 0.5 ! add increased weight due to internal fluid PI = 5000 ! uniform internal pressure MAT = 1 DT = 25 ! non uniform temperature increase MAT = 2 DT = 15 *LOAD_STEP_TITLE Internal pressure and temperature loads *ANALYSE ! solve for additional loads ################################################################

55


DATA INPUT

################################################################# # DEMONSTRATION DATA FILE FOR 3D TRENCHING ANALYSIS # # Data file prepared 22 February 1993, by D.Cathie # # Pipe data: # outside diameter = 0.273 m # thickness = 0.015 m # modulus of elasticity = 207e6 kN/m**2 # ################################################################ *JOB_TITLES Trenching analysis : lay tension 375 kN Pipe response to lateral loads *CONTROL 12 13 18

1 10 0

! One increment for lay tension ! Divide each segment into 10 ! Switch off pipe plasticity

*THREE_DIMENSIONAL

! R equired t o r ead i n 3 D K P_Values

*KP_VALUES #

KP 0. 100.

Y -30. -30.

X

200. 250. 280. 300. 305. 310. 330. 350. 400. 500. 600.

-30. -30. -30. -30. -31.179 -31.179 -31.179 -31.179 -31.179 -31.179 -31.179

*TWO_DIMENSIONAL

1 1

0. 0.

200. 250. 280. 300. 304. 310. 330. 350. 400. 500. 600.

0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.

! Switch back to 2D for speed

*LH_RH_RESTRAINTS 0 1

Z 0. 100.

! For laydown 1 0

*NODAL_SPRINGS 0.0 299. 0 299. 301. 0 301. 600. 0

! vertical only 2 2

0 0

5

0

no axial during laydown

! undisturbed ! for use eventually to model weakened crest ! disturbed (trench)


56

DATA INPUT

*SPRING_CURVES 2 -1.0E99 0.0 .037 .075 .112 .149 .187 373.1 5 -1.0E99 0.0 .037 .075 .112 .149 .187 373.1 *MAT_PROPS MAT = Do = Ts = E = V = KT = BF =

8 0.0 0.0 9.35 18.26 25.98 32.08 36.25 36.25

!undisturbed medium dense medium sand

8 0.0 0.0 6.08 11.97 17.12 21.26 24.14 24.14

!disturbedmediumsand

1 0.2731 0.01427 207.0E6 0.3 1.1394e-5 0.85

*NODAL_LOADS 600. 375.

0.

0.

!lay tension

*LOAD_STEP_TITLE Apply 375 kN tension *NO_OUTPUT

! do not output data for tension stage

*HORIZONTAL_PIPE *ANALYSE !forlaytension C----------------------------------------------------------------------------*LOAD_STEP_TITLE Laydown under self weight only *MAT_PROPS MAT = 1 UDL = -1.3507 *CONTROL 12

20

! udl of self weight ! Nominal increment no: 20

*ANALYSE !Laydownanalysis C----------------------------------------------------------------------------*CONTROL 12

2

*ZERO_AXIAL_DISPS

! Nominal 2 increments for 3D switching ! Any axial disps accrued to this point ! must not affect axial spring forces

57


DATA INPUT

*WRAP_INTO_3D *LOAD_STEP_TITLE Switch to 3D without load *NODAL_SPRINGS 0.0 299. 4 2 0 4 0 0 299. 301. 4 2 0 4 0 0 301. 600. 4 5 0 4 0 0 *AXIAL_SPRINGS 4 0.003

0.0

*LH_RH_RESTRAINTS 0 0 0 0 0 0 0 0 0 0

! Curve 4 for both axial and lateral ! Axial - position 1 (X) ! Lateral - position 4 (Z)

0.7

! Axial and lateral friction ! fully restrained at ends from now on

0 0

*NO_OUTPUT

! don't output results for this "artificial" stage

*ANALYSE ! for switching to 3D analysis (no loads ! because the pipe is straight C----------------------------------------------------------------------------*LOAD_STEP_TITLE Horizontal lateral load : 10kN *CONTROL 12 17 16

50 2 0

! no of load increments ! tangent method with calc of soil reactions ! switch off scale back

*NODAL_LOADS 302.0

0.

0.

0.

10.

0.

0.

*ANALYSE ! at 10kN total lateral C----------------------------------------------------------------------------*LOAD_STEP_TITLE Horizontal lateral load : 20kN *NODAL_LOADS 302.0 0.

0.

0.

10.

0.

0.

*ANALYSE ! at 20kN total lateral C----------------------------------------------------------------------------*LOAD_STEP_TITLE Horizontal lateral load : 30kN *NODAL_LOADS 302.0

0. 0.

0.

*ANALYSE

10.

0.

0.

! at 30kN total lateral

C----------------------------------------------------------------------------*LOAD_STEP_TITLE Horizontal lateral load : 40kN *NODAL_LOADS 302.0

0. 0.

0.

10.

0.


0.

58

DATA INPUT

*ANALYSE ! at 40kN total lateral C----------------------------------------------------------------------------*LOAD_STEP_TITLE Horizontal lateral load : 50kN *NODAL_LOADS 302.0 *ANALYSE

59

0. 0.

0.

10.

0.

0.

! at 50kN total lateral


DATA OUTPUT

3. DATA OUTPUT 3.1. Introduction PipeNet produces several output files. The output files of use to the User are the Stress table file (*.STR), the full output file (*.OUT) and the plot file (*.PLT). These files are described in this section using the 2D demonstration problem presented in Section 2.5.0. The following sign convention applies:

Figure 6: Sign Convention.


60

DATA OUTPUT

3.2. Format of Stress Table File *.STR The .STR file is a Stress table with summarised results in a printable format. The full file is shown overleaf. Following the header and job title echo, the load step title signals the start of the output for the load step. The columns are defined as listed below. The set of information is then repeated for each load step, unless the *NO_OUTPUT keyword has been invoked for that load step.

ColumnHeader

Units

Description

PlanKP

m

KPvalueinhorizontalplane(inplan) defining seabed and pipe elevation

Seabed Elevation

m

Depth of seabed below datum (usually water depth)

Pipe Elevation

m

Calculated bottom of pipe depth (to be compared with seabed depth)

Bending Stress(*)

kPa

Outer fibre stress due to bending at the top of the pipe

Axial Stress(*)

kPa

True wall axial stress

HoopStress(*)

kPa

Hoopstress

EquivalentStress(*) Fibre Strain(*)

kPa -

StressCombination Combined maximum axial and bending strain at the outer fibre

Reaction Force

kN

Force in theverticalsoil spring

(*) For definition, please refer to SAGE Profile User Manual Volume 3.

Comments:

• All parameters having different values at each end of an element (e.g. stresses, strains) are output for the left hand end of each element, except for the last element. This sometimes gives the appearance of non-symmetric results for a symmetric problem. A complete set of stresses is given in the full output file *.OUT (see below).

• Small bending stresses will be apparent even on a flat seabed. This arises because the distributed loads are modelled in a consistent manner and thus induce a nodal moment as well as a nodal load. Soil support is modelled for translation movements only - therefore no rotational springs are present from the soil to support the pipe.

• In 3D analyses, the bending stress shown in this column is taken as the stress corresponding to the total section moment in the upper half of the pipe. This defaults to the 2D result if bending is purely in the vertical plane.

61


DATA OUTPUT

• The equivalent stress is calculated for both values of the bending stress on either side of the neutral axis and the maximum σeq is printed. • The fibre strain is the combined maximum axial and bending strain at the outer fibre. The bending strain is taken with the same sign as the axial strain to find the maximum value. Note that the axial strain component is the deformation or extension strain.


62

DATA OUTPUT

3.3. EXAMPLE OF STRESS TABLE OUTPUT *.STR ====================== PIPELINE PROFILE ANALYSIS PROGRAM ===================== Version 3d9d ============================================================================== Job started: 17:21:27 Thursday, 06 May 1993 Demonstration problem for a typical pipeline analysis on a flat seabed with non linear properties Input File: DEMO1.DAT Step Tit le: Apply la y ten sion Plan KP Seabed Pipe Elev. Elev. (m) (m) (m) 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0

Bending Axial Hoop Equiv. Fibre React Stress Stress Stress Stress Strain Force (N/mm2) (N/mm2) (N/mm2) (N/mm2) (%) (KN)

-100.000 -100.000 0 .00 -100.000 -100.000 0.00 -100.000 -100.000 0 .00 -100.000 -100.000 0 .00 -100.000 -100.000 0.00 -100.000 -100.000 0.00 -100.000 -100.000 0.00 -100.000 -100.000 0.00 -100.000 -100.000 0.00 -100.000 -100.000 0.00 -100.000 -100.000 0.00

-5.59 -16.7 9 14.81 -5.59 -16.79 14.81 -5.59 -16.7 9 14.81 -5.59 -16.7 9 14.81 -6.91 -16.79 14.62 -6.91 -16.79 14.62 -6.91 -16.79 14.62 -6.91 -16.79 14.62 -6.91 -16.79 14.62 -6.91 -16.79 14.62 -6.91 -16.79 14.62

0.000 0.00 0.000 0.00 0.000 0.00 0.000 0.00 -0.001 0.00 -0.001 0.00 -0.001 0.00 -0.001 0.00 -0.001 0.00 -0.001 0.00 -0.001 0.00

Input File: DEMO1.DAT Step Title: Laydown case with pipe empty Plan KP Seabed Pi pe Elev. Elev. (m) (m) (m) 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0

63

-100.000 -100.000 -100.000 -100.000 -100.000 -100.000 -100.000 -100.000 -100.000 -100.000 -100.000

Bending A xial Hoop Equiv. Fibre React Stress Stress Stress Stress Strain Force (N/mm2) (N/mm2 (N/mm2) (N/mm2) (%) (KN)

-100.000 -100.000 -100.000 -100.000 -100.005 -100.012 -100.021 -100.030 -100.036 -100.040 -100.041

0.00 -0.84 1.23 11.36 6.26 4.32 -1.54 -3.96 -4.53 -4.40 -4.28

-5.59 -5.59 -5.59 -5.59 -6.91 -6.91 -6.91 -6.91 -6.91 -6.91 -6.91

-16.79 -16.79 -16.79 -16.79 -16.79 -16.79 -16.80 -16.80 -16.80 -16.80 -16.80

14.81 14.99 15.09 20. 30 16.48 15.66 14.86 15.54 15.74 15.70 15.65

0.000 0.000 0.001 0.006 0.003 0.002 0.001 0.002 0.002 0.002 0.002

2.45 2.43 0.00 12.26 2.29 6.12 2.14 2.98 3.61 3.98 2.05


DATA OUTPUT

Input File : DEMO1.DAT Step Title:

Internal pressure and temperature loads

Plan KP Seabed Pipe Elev. Elev. (m) (m) (m) 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0

-100.000 -100.000 -100.000 -100.000 -100.000 -100.000 -100.000 -100.000 -100.000 -100.000 -100.000

-100.000 -100.000 -99.999 -100.000 -100.008 -100.021 -100.038 -100.053 -100.064 -100.071 -100.073

Bending Axial Hoop Equiv. Fibre React Stress Stress Stress Stress Strain Force (N/mm2) (N/mm2) (N/mm2) (N/mm2) (%) (KN) 0.00 -1.51 2.26 18.15 12.05 8.90 -2.74 -7.82 -8.67 -7.78 -7.14


-11.98 -11.97 -11.97 -11.78 -12.99 -12.87 -5.17 3.50 13.77 25.45 25.45

61.54 61.54 61.54 61.54 61.54 61.54 61.53 61.53 61.53 61.53 61.53

68.33 69.27 69.75 80.78 77.17 74.84 65.85 63.80 59.15 54.87 54.72

0.015 0.016 0.017 0.013 0.010 0.008 0.009 0.016 0.021 0.027 0.026

64

4.06 3.81 0.00 17.09 3.78 10.46 3.75 5.28 6.40 7.05 3.63

DATA OUTPUT

3.4.

Format of full output file *.OUT For each load stage (unless output is inhibited), the output is presented in the following sections: ColumnHeader NN KP Bed-elev Pipe-elev Seabed-x Seabed-y Disp-x Disp-y Disp-θ Disp-Z Disp-α Disp-β NN React-x React-y React-θ ReactZ React α React β Equil-x Equil-y Equil-θ EquilZ Equil-α Equil β NN Mat Force-ax ShearF-V BM-V

65

Units

Description *Nodal Value !—(global) Node number value KP Seabedelevation Pipeelevation

m m m m m m Displacementintheglobalx-axis m Displacementintheglobaly-axis rad Rotation around the global z-axis m DisplacementintheglobalZ-direction rad Rotation around global Y-axis rad Rotation around global X-axis *Nodal_Reactions_and_Equilib !—(global) Node number kN Forceintheaxialsoilspring kN Forceintheverticalsoilspring kNm Reaction moment in the rotational XY-soil spring (should be always zero) kN Forceinthelateralsoilspring kNm Reaction moment in the rotational XZ soil spring (see notes) kNm Reaction moment in the rotational YZ soil spring (see notes) kN Out-of- Balance force in the x direction Reaction for a fixed DOF (see note) kN Out –of- Balance force in the y direction Reaction for a fixed DOF (see note) kN Out-of-Balance moment around the z-axis Reaction for a fixed DOF (see note) kN OutofbalanceforceinglobalZ Reaction for a fixed DOF (see notes) kNm Out of balance moment around Y-axis Reaction for a fixed DOF (see notes) kNm Out of balance moment around X-Axis Reaction for a fixed DOF (see notes) *Element_Forces !—(local) Node number Material type index kN Effective axial force (positive in tension ) in the local x-axis kN Shearforceinthe local y-direction kNm Bending moment around the local z-axis


DATA OUTPUT

ShearF-L BM-L Torsion

kN

Shear force in the local z-direction(always zero in 2D) kNm Bending moment around the local y-axis (always zero in 2D) kNm Torquearoundthelocalx-axis (always zero in 2D) *Element_Curvatures !—(local)

NN K-elast-V

m--1

K-elast-L

m-1

K-plast-V

m-1

K-plast-L K-total N- axis-β

NN σ-ax

Elastic curvature in Node thenumber vertical plane; corresponding to Mz (BM- V) Elastic curvature in the horizontal plane; corresponding to My (BM-L)

Plastic curvature in the vertical plane; corresponding to Mz (BM- V) m Plastic curvature in the horizontal plane; corresponding to My (BM- L) m -1 Total curvature Slope of the neutral axis defined as 90<θ<90 from the horizontal (i.e. bending in vertical plane only in 2D gives θ =0) *Element_Stresses !—(local) Node number kPa True-wallaxialstress -1

Bending stressdue to M z (BM-V) at the top of pipe (outer fibre) σ-long(-) kPa Minimum of the sum of the axial and bending stresses σ-long(+) kPa Maximum of the sum of the axial and bending stresses σ-hoop kPa Hoop stress due to pressure difference σ-shear kPa ShearstressduetoT y (ShearF-V) σ-equiv kPa Combinedstress *Element_Strains !—(local – defomation strains) NN Node number ε-ax Axial strain computed as the change in length of an element. ε-bend Bendingstraincorrespondingto σ- bend ε-long(-) Minimum longitudinal strain corresponding to σlong(-) ε-long(+) Maximum longitudinal strain corresponding to σlong(+) ε-hoop Hoopdeformation εxh ε-shear Sheardeformation εxy * Integrated_Pipe_Stresses (only for stress- strain based moment- curvature method) Axial, hoop and longitudinal stresses at different segments around the circumference of the pipe. σ-bend

kPa


66

DATA OUTPUT

Integrated_Pipe_Strains (only for stress-strain based moment-curvature method) Axial, hoop and longitudinal strains at different segments around the circumference of the pipe. Important notes: 1. The “Equil-…” columns give the nodal summations of internal and external forces and the soil spring reaction. Therefore, it represents the out-of-balance force which should be zero if the analysis has converged properly. However, if the node is restrained (i.e. imposed displacement), the value corresponding to the restrainded dof is the opposite of the support reaction. 2. The true-wall axial stress corresponds to the true-wall axial force and is computed by removing the end effects of the fluid pressure from the FE calculated axial force (for details see SAGE Profile User Manual Volume 3). 3. The axial strain is the deformation strain (i.e. the change in length of an element) not the true strain accounting for initial strains such as thermal effects etc. 4. Notes of the *.STR output file description are still valid. For further details, please refer to SAGE Profile User Manual Volume 3. To view correctly the Greek character in the *.OUT and *.STR files, the “Terminal” font should be used together with the OEM/DOS script.

67


DATA OUTPUT

3.5. EXAMPLE OF 2D OUTPUT FILE *.OUT #----------------------------------------------------------------------------# PIPELINE PROFILE ANALYSIS PROGRAM Version 4_36 # # Job started: 11:30:07 Thursday, 09 March 1995 #----------------------------------------------------------------------------*JOB_TITLES Example no 7a: Pipe on an elevated obstruction *Load_Step_Number 1 *Load_Step_Title Self weight and residual tension *Nodal_Values !-- (Global) # NN 1 2 3 4 5 6 7 8 9 10 11 12 13

KP (m ) 0.000000E+00 30.0000 60.0000 90.0000 120.00. 145.000 150.000 155.000 180.000 210.000 240.000 270.000 300.000

Bed elev -100.000 -100.000 -100.000 -100.000 -100.000 -100.000 -98.2800 -100.000 -100.000 -100.000 -100.000 -100.000 -100.000

Pipe e le v -100.0 00 -100.0 00 -100.0 00 -100.0 00 -99.21 39 -98.32 70 -98.28 00 -98.32 70 -99.21 39 -100.0 00 -100.0 00 -100.0 00 -100.0 00

*Nodal_Reactions_and_Equilib # NN 1 2 3 4 5 6 7 8 9 10 11 12 13

coarse mesh

S ea b ed x Seabed y Disp x Di s p y Disp θ 0.0000 00E+00 -1 00.000 0.0000 00E+00 -0.586508E-0 7 -0.354266E-02 30.000 0 -1 00.000 0.6669 24E-02 -0.732681E-0 7 0.1453 30E-02 60.000 0 -1 00.000 0.1268 11E-01 -0.100043E-0 6 -0.293598E-02 90.000 0 -1 00.000 0.1798 04E-01 -0.767378E-0 8 0.1071 15E-01 120.00 0 -1 00.000 0.121686 E-01 0.78 6123 0.397753 E-01 145.00 0 -1 00.000 -0.800538E-03 1.67 296 0.176124 E-01 150.00 0 -9 8.2800 -0.576920E-03 -0.177231E-0 5 -0.133737E-06 155.00 0 -1 00.000 -0.356595E-03 1.67 296 -0.176126E-01 180.00 0 -1 00.000 -0.134282E-01 0.78 6121 -0.397754E-01 210.00 0 -1 00.000 -0.195024E-01 -0.767243E-0 8 -0.107114E-01 240.00 0 -1 00.000 -0.145550E-01 -0.100044E-0 6 0.2936 17E-02 270.00 0 -1 00.000 -0.893625E-02 -0.732679E-0 7 -0.145309E-02 300.00 0 -1 00.000 -0.267201E-02 -0.586391E-0 7 0.3542 79E-02

!--

(Global)

R ea ct -x R ea c t - y Re ac t - θ 0 .0 0 0 0 0 0 E + 0 0 8 .7 9 7 6 2 0.00 00 00 E +0 0 0.000000E+ 00 21.9 804 0.000000E+00 0.000000E+ 00 30.0 130 0.000000E+00 0.000000E+ 00 2.30 213 0.000000E+00 0.000000E+ 00 0.00 0000E+00 0.000000E+00 0.000000E+ 00 0.00 0000E+00 0.000000E+00 0 .0 0 0 0 0 0 E + 0 0 8 8 . 6 1 5 5 0.00 00 00 E +0 0 0 .0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0 . 0 0 0 0 0 0 E + 0 0 0.000000E+ 00 0.00 0000E+00 0.000000E+00 0.000000E+ 00 2.30 173 0.000000E+00 0.000000E+ 00 30.0 133 0.000000E+00 0.000000E+ 00 21.9 804 0.000000E+00 0.000000E+ 00 8.79 587 0.000000E+00


E q ui l- x 3 99 .98 3 -0.2 18913E-01 -0.1 22489 -0.5 12532E-01 -0.2 38248 0.302668 - 0.6 24 98 1E -0 4 - 0.3 02 71 0 0.238279 0.513106E-01 0.122496 0. 218928E-01 0. 167422E-01

E qu il -y - 0.17 80 83 -0.277255 -2.28658 3.05153 3.25864 -2.34161 - 2.44 88 2 - 2.34 16 0 3.25867 3.05163 -2.28664 -0.277264 -0.177948

Eq u ilθ- 0 .4 5 9 2 3 6 E - 1 3 -0.120792E-12 0.1278 98E-12 0.7105 43E-13 -0.213163E-13 0.1136 87E-12 0 .0 0 0 0 0 0 E + 0 0 - 0 .5 6 8 4 3 4 E - 1 3 -0.106581E-12 0.4263 26E-13 -0.284217E-13 -0.113687E-12 -0.378221E-13

68

DATA OUTPUT

*Element_Forces # NN 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13

Ma t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

!-- (local) F or ce -a x 3 9 9 .9 8 3 3 9 9 .9 9 3 3 9 9 .9 7 1 3 9 9 .9 9 5 3 9 9 .8 7 3 4 0 0 .0 2 0 3 9 9 .8 7 5 4 0 0 .4 2 1 4 0 0 .3 9 9 4 0 0 .8 7 4 4 0 0 .2 3 4 4 0 0 .2 5 7 4 0 0 .2 5 7 4 0 0 .2 3 4 4 0 0 .8 7 4 4 0 0 .3 9 9 4 0 0 .4 2 1 3 9 9 .8 7 5 4 0 0 .0 2 0 3 9 9 .8 7 3 3 9 9 .9 9 5 3 9 9 .9 7 1 3 9 9 .9 9 3 399.983

S he ar F -V - 8.97 5 71 1 2 .5 0 4 2 - 9.75 3 46 1 1 .7 2 6 4 - 2 0 .5 7 3 2 0 .9 0 6 0 1 7 - 8.82 4 40 1 2 .6 4 8 5 1 2 .1 9 9 6 3 0 .0 9 2 8 3 8 .1 8 8 0 4 1 .7 6 8 0 - 4 1 .7 7 0 0 - 3 8 .1 9 0 1 - 3 0 .0 9 4 9 - 1 2 .2 0 1 7 - 1 2 .6 5 0 6 8.8 22 36 - 0 .9 0 7 6 2 3 20 .5 71 6 - 1 1 .7 2 8 4 9.7 51 51 - 1 2 .5 0 6 1 8.97382

*Element_Curvatu res # NN 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13

69

K-elast-V -341361E-18 -0.426180E-03 -0.426180E-03 -0.740968E-03 -0.740968E-03 0.846772E-03 0.846772E-03 0.470674E-03 0.470674E-03 -0.281934E-02 -0.281934E-02 -0.426105E-02 -0.426105E-02 -0.281934E-02 -0.281934E-02 0.470682E-03 0.470682E-03 0.846803E-03 0.846803E-03 -0.740968E-03 -0.740968E-03 -0.426171E-03 -0.426171E-03 0.281141E-18

K-elast-L 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

B M -V Sh ea r F- L BM L Torsion - 0 .4 5 9 2 3 6 E - 1 3 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0 .00 00 00 E +0 0 - 5 7.33 43 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 5 7.33 43 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 9 9.68 30 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 9 9.68 30 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 1 1 3 .9 1 7 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 1 1 3 .9 1 7 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 6 3.32 02 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 6 3.32 02 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 3 7 9 .2 8 8 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 3 7 9 .2 8 8 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 5 7 3 .2 4 3 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 5 7 3 .2 4 3 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 3 7 9 .2 8 8 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 3 7 9 .2 8 8 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 6 3.32 12 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 6 3 .3 2 1 2 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 1 1 3 .9 2 1 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 1 1 3 .9 2 1 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 9 9.68 30 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 9 9.68 30 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 5 7.33 32 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 - 5 7.33 32 0 . 0 0 0 0 0 0 E + 0 0 0 .0 0 0 0 0 0 E + 0 0 0.00 00 00 E +0 0 0.378221E-13 0.000000E+00 0.000000E+00 0.000000E+00

!-- (local) K-plast-V 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

K-plast L K-total N-axisß 0.000000E+00 -0.341361E-18 0.000000E+00 0.000000E+00 -0.426180E-03 0.000000E+00 0.000000E+00 -0.426180E-03 0.000000E+00 0.000000E+00 -0.740968E-03 0.000000E+00 0.000000E+00 -0.740968E 03 0.000000E+00 0.000000E+00 0.846772E-03 0.000000E+00 0.000000E+00 0.846772E-03 0.000000E+00 0.000000E+00 0.470674E-03 0.000000E+00 0.000000E+00 0.470674E-03 0.000000E+00 0.000000E+00 -0.281934E-02 0.000000E+00 0.000000E+00 -0.281934E-02 0.000000E+00 0.000000E+00 -0.426105E-02 0.000000E+00 0.000000E+00 -0.426105E-02 0.000000E+00 0.000000E+00 -0.281934E-02 0.000000E+00 0.000000E+00 -0.281934E-02 0.000000E+00 0.000000E+00 0.470682E-03 0.000000E+00 0.000000E+00 0.470682E-03 0.000000E+00 0.000000E+00 0.846803E-03 0.000000E+00 0.000000E+00 0.846803E-03 0.000000E+00 0.000000E+00 -0.740968E-03 0.000000E+00 0.000000E+00 -0.740968E-03 0.000000E+00 0.000000E+00 -0.426171E-03 0.000000E+00 0.000000E+00 -0.426171E-03 0.000000E+00 0.000000E+00 0.281141E-18 0.000000E+00


DATA OUTPUT

*Element_Stresse s # NN σ- ax 1 17500.8 2 17501.3 2 17500.3 3 17501.4 3 17496.0 4 17502.5 4 17496.1 5 17520.0 5 17519.0 6 17539.8 6 17511.8 7 17512.8 7 17512.8 8 8 9 9 10 10 11 11 12 12 13

17511.8 17539.8 17519.0 17520.0 17496.1 17502.5 17496.0 17501.4 17500.3 17501.3 17500.8

σ-long(-)

1409 67. 140967. -23534.1 -23534.1 -42340.2 -42340.2 37048.4 37048.4 21308.6 21308.6 -0.140570E-10

*Element_Strains # NN 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13

!-- (local)

σ-bend .170681E-10 2130 9.0 2130 9.0 3704 8.4 3704 8.4 -42338.6 -42338.6 -23533.7 -23533.7 1409 67. 1409 67. 2130 53. 2130 53.

ε-ax

0.875207E-04 0.875207E-04 0.875178E-04 0.875178E-04 0.875077E-04 0.875077E-04 0.875494E-04 0.875494E-04 0.876528E-04 0.876528E-04 0.875654E-04 0.875654E-04 0.875654E-04 0.875654E-04 0.876524E-04 0.876524E-04 0.875487E-04 0.875487E-04 0.875066E-04 0.875066E-04 0.875166E-04 0.875166E-04 0.875196E-04 0.875196E-04

σ-long(+)

σ-hoop

σ-shear

σ-equiv

17500.8 -3807.73 -3808.68 -19547.0 -19552.4 -24836.2 -24842.5 -6013.71 -6014.69 -123427. -123455. -195540. -195540.

17500.8 38810.2 38809.3 54549.8 54544.4 59841.1 59834.7 41053.7 41052.7 158507. 158479. 230565. 230565.

0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

0.000000E+00 0.000000 E+00 0.000000 E+00 0.000000 E+00 0.000000 E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000 E+00 0.000000 E+00 0.000000 E+00 0.000000 E+00

17500.8 38810.2 38809.3 54549.8 54544.4 59841.1 59834.7 41053.7 41052.7 158507. 158479. 230565. 230565.

-123455. -123427. -6015.09 -6014.11 -24844.1 -24837.7 -19552.4 -19547.0 -3808.27 -3807.31 17500.8

158479. 158507. 41053.1 41054.1 59836.3 59842.6 54544.4 54549.8 38808.9 38809.8 17500.8

0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

0.000000 E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

158479. 158507. 41053.1 41054.1 59836.3 59842.6 54544.4 54549.8 38808.9 38809.8 17500.8

!-- (local - deformation strains)

ε-bend

0.853403E-19 0.106545E-03 0.106545E-03 0.185242E-03 0.185242E-03 -0.211693E-03 -0.211693E-03 -0.117669E-03 -0.117669E-03 0.704835E-03 0.704835E-03 0.106526E-02 0.106526E-02 0.704834E-03 0.704834E-03 -0.117671E-03 -0.117671E-03 -0.211701E-03 -0.211701E-03 0.185242 E-03 0.185242 E-03 0.106543 E-03 0.106543 E-03 -0.702852E-19

ε-long(-)

0.875207E-04 -0.190242E-04 -0.190272E-04 -0.977242E-04 -0.977343E-04 -0.124185E-03 -0.124144E-03 -0.301191E-04 -0.300158E-04 -0.617182E-03 -0.617269E-03 -0.977698E-03 -0.977698E-03 -0.617269E-03 -0.617182E-03 -0.300181E-04 -0.301219E-04 -0.124152E-03 -0.124194E-03 -0.977354E-04 -0.977254E-04 -0.190262E-04 -0.190233E-04 0.875196E-04


ε-long(+)

0.875207E-04 0.194066E-03 0.194063E-03 0.272760E-03 0.272750E-03 0.299201E-03 0.299242E-03 0.205218E-03 0.205321E-03 0.792488E-03 0.792400E-03 0.115283E-02 0.115283E-02 0.792400E-03 0.792487E-03 0.205323E-03 0.205219E-03 0.299249E-03 0.299207E-03 0.272749E-03 0.272759E-03 0.194060E-03 0.194062E-03 0.875196E-04

ε-hoop

0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+ 00 0.000000E+ 00 0.000000E+ 00 0.000000E+ 00 0.000000E+00

ε-shear

0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

70

DATA OUTPUT

3.6. Format of plot file *.PLO The plot file consists of 20 columns of data, preceded by a header giving run information. Only the last load stage is saved in the plot file. Immediately below the *Results keyword, the integer value indicates the number of rows of data following. The example plot file is given overleaf. Nodal values are given where appropriate. For results such as bending moments, values from the left-hand end of the element are presented, except for the last element when both are printed.

ColumnHeader

71

Units

Description

KP

m

KP value in horizontal plane (in plan) defining seabed and pipe elevation

Seabed-y

m

Depth of seabed below datum (usually water depth)

Pipe-y

m

Calculated bottom of pipe depth (to be compared with seabed depth)

M

-

BM-max

kNm

Maximum bending moment (taken as the square root of local vertical and horizontal moments)

Curv-max

m-1

Maximum elastic and plastic curvature

ε-ax-def

-

Axial (deformation) strain (i.e. corresponding to the change in element length)

ε-bend-max

-

Maximumbendingstrain

σ-ax-tw

MPa

True-wallaxialstress

σ-bend-max

MPa

σ-hoop

MPa

Hoop stress due to pressure difference

F-eff

kN

Effectiveaxialforce

X

m

Global X-coordinate of KP value for initial route

Z

m

Global Z-coordinate of KP value for initial route

X+Dx

m

Final global X-coordinate of KP value of pipe

Z+Dz

m

Final global Z-coordinate of KP value of pipe

Material type index

Bending stress (i.e. axial stress due to bending moment at the outer fibre)


DATA OUTPUT

ColumnHeader

Units

Description

ε-ax-tw

-

True-wall axial strain (corresponds to true-wall axial stress)

ε-pl-long

-

Maximum longitudinal plastic strain around the section (if calculated)

ε-pl-equiv

-

Maximum equivalent plastic strain around the section (see note)

Important note: Columns 19 and 20 are only non-zero if the stress-strain based moment-curvature method is being used (*CONTROL 18 = 6) and if plasticity has occurred. Note that the maximum longitudinal plastic strain is the maximum strain in the longitudinal direction around the pipe section. It is an average value across the pipe wall and is calculated at the sampling points spread evenly around the section. It may therefore be slightly less than the plastic strain as derived from the plastic curvatures at the outer fibre of the pipe. The equivalent plastic strain εpeq is normally derived from the component plastic strains in the principal directions which are not computed in the simplified pipe bending model. However, as shown by Klever et al (1994)1, it can be approximated by basing it on the longitudinal plastic strain εpx and the ratio of the hoop stress to the yield stress using the formula :

p

ε eq

=

ε xp

1-

where

m=

3 4

m

2

σ x / σh

Since this approximate formula does not account for reductions in the hoop stress, in the program the maximum value calculated during a series of load stages is output. For complex loading cases, is it recommended to base engineering decisions on the longitudinal plastic strain rather than the equivalent strain.

1

Klever, F.J., Palmer, A.C. and Kyriakides S. (1994), Limit State Design of High Temperature Pipelines, Offshore Mechanics in Arctic Engineering, Vol V, Pipeline Technology, pp77-92.


72

DATA OUTPUT

3.7. EXAMPLE OF 2D PLOT FILE *.PLO *JOB_TITLES 2 Example no 7a: Pipe on an elevated obstruction - coarse mesh *Load_Step 1 : Self weight and residual tension *Time 11:30:14 *Results

Thursday, 09 March

1995

KP S e ab ed-y P ip e- y M BM -m ax C ur v- m ax - a x - de f - b e n d- m a x 0.000000E +00 -0 .100000E+ 03 -0.100000E +03 1 -0.4592 36E-13 -0.34136 1E-18 0.87520 7E-04 0.853403E-1 9 0.300000E+02 -0. 100000E+ 03 -0.100000E +03 1 -0.573343E+02 -0.42618 0E-03 0.875178E-04 0.106545E-03 0.600000E+02 -0. 100000E+ 03 -0.100000E +03 1 -0.996830E+02 -0.74096 8E-03 0.875077E-04 0.185242E-03 0.900000E+02 -0 .100000E+03 -0.100000E +03 1 0.1139 17E+03 0.846772E-03 0.875494E-04 -0.211693E-0 3 0.120000E+03 -0.100000E+03 -0.99 21 39 E +0 2 1 0 .6 3 3 2 0 2 E + 0 2 0.47 0 67 4-03 E 0.876528E-04 -0.117669E-03 0.145000E+03 - 0.100000E+03 -0.983270E+02 1 -0.379288E+03 -0.281934E-02 0.875654E-04 0.704835E-03 0.150000E+03 - 0.982800E+02 -0.982800E+02 1 -0.573243E+03 -0.426105E-02 0.875654E-04 0.106526E-02 0.155000E+03 -0 .100000E+03 -0.983270E +02 1 -0.379288E+03 -0.28193 4E-02 0.876524E-04 0.704834E-03 0.180000E+03 -0 .100000E+03 -0.992139E +02 1 0.6332 12E+02 0.470682E-03 0.875487E-04 -0.117671E-0 3 0.210000E+03 -0.100000E+03 -0.10 00 00 E +0 3 1 0 .1 1 3 9 2 1 E + 0 3 0.84 6 80 3-03 E 0.875066E-04 -0.211701E-03 0.240000E +03 -0 .100000E+ 03 -0.100000E +03 1 -0.9968 30E+02 -0.74096 8E-03 0.87516 6E-04 0.185242E-0 3 0.270000E+03 -0. 100000E+ 03 -0.100000E +03 1 -0.573332E+02 -0.42617 1E-03 0.875196E-04 0.106543E-03 0.300000E+03 -0 .100000E+03 -0.100000E +03 1 0.3782 21E-13 0.281141E-18 0.875196E-04 -0.702852E-1 9

(columns continued) ax tw 0.175008E+02 0.175003E+02 0.174960E+02 0.174961E+02 0.175190E+02 0.175118E+02 0.175128E+02 0.175398E+02 0.175200E+02 0.175025E+02 0.175014E+02 0.175013E+02 0.175008E+02

bend max 0. 170681E- 13 0.213090E+02 0.370484E+02 -0.423386E+02 -0.235337E+02 0.140967E+03 0.213053E+03 0.140967E+03 -0.235341E+02 -0.423402E+02 0.370484E+02 0.213086E+02 -0.140570E-13

hoop 0.000000E+ 00 0.0000 00E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

equiv F e ff X 0.175008E+02 0.399983E+03 0.388093E+02 0.399971E+03 0.545444E+02 0.399873E+03 0.598347E+02 0.399875E+03 0.410527E+02 0.400399E+03 0.158479E+03 0.400234E+03 0.230565E+03 0.400257E+03 0.158507E+03 0.400874E+03 0.410541E+02 0.400421E+03 0.598426E+02 0.400020E+03 0.545498E+02 0.399995E+03 0.388098E+02 0.399993E+03 0.175008E+02 0.399983E+03

Z 0.0000 00E+00 0.300000E+02 0.600000E+02 0.900000E+02 0.120000E+03 0.145000E+03 0.150000E+03 0.155000E+03 0.180000E+03 0.210000E+03 0.240000E+03 0.270000E+03 0.300000E+03

0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

(columns continued) X + Dx 0.000000E+00 0.300067E+02 0.600127E+02 0.900180E+02 0.120012E+03 0.144999E+03 0.149999E+03 0.155000E+03 0.179987E+03 0.209980E+03 0.239985E+03 0.269991E+03 0.299997E+03

73

Z + dZ 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

ax tw 0.87 5042E-04 0.87 5015E-04 0.874801E-04 0.874805E-04 0.875951E-04 0.875590E-04 0.875640E-04 0.876991E-04 0.876000E-04 0.875123E-04 0.875069E-04 0.875063E-04 0.875042E-04

pl long 0.000000 E+00 0.000000 E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00

pl equiv 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00


SAGE Profile V6.3.2 User Manual - Volume 2

Recommend Documents