usfos introduction

8/11/2019 Usfos Introduction

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USFOS Analysis(Ultimate Strength for Framed

Offshore Structures)- A nonlinear numerical tool mainly for the

analysis of space frames

- Pushover analysis

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Outline

Features of USFOS

USFOS input file preparation

Running analysis & post-processing

Examples: simply supported beam

Examples: 2D frame and jacket

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Basic features

Ultimate Strength for FramedOffshore Structures

Beam, Shell, Solid Elementsone finite element is sufficient for one physical

member based on element formulation

Nonlinearities: geometry,

material and boundary

conditions

Consistent Unit SystemN (force), m (length) E in Pa

N (force), mm (length) E in MPa

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Add-on features

Joint Capacity Checks

Spud Can

Soil-Structure Interaction

Hydrodynamic Loading

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F ile Types I nvolved in And Analysis

USFOS

R e a l i t y E n g i n e e r i n g

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Usfos(engine)

Structural

input fil e-

model.fem

USFOS analysis

control fi le

(named f ex head.fem)

Result

Database

for XACT.

Name:

res.raf

Xact(Graphical Interface)

Text output f il e (res.out).

Contains general print and

err or messages

INPUT OUTPUT


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Installing software

Download from http://www.usfos.com/

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Installing software

Replace the key file at C:\Program

Files\USFOS\bin

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Open software

Open from start all programs USFOS

USFOS GUI

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Run software (1)

Open analysis control

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Run software (2)

Input example file byclicking

Example files are

available in C:\Program

Files\USFOS\examples

You can edit the examplefile by clicking

Save the file before

running.

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Head_orig.fem

model.fem

Left empty

Name the result

file in the same

folder

Attention: In PC cluster, drive C is protected, users cant write

any files on it. But you can write files on desktop. So before running the

software, you have to copy the example files to desktop and name your

result file in the same folder on the desktop.

If you forget this for the first time, restart USFOS.


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Analysis results

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Change loadstep

Try this by

yourself

Drag with the left button orthe right button to translate

or rotate

View the node numbers

and element numbersView the animation


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P

Step1: model structure

Step2: add loading condition

A

P

B

l

x

y

z

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USFOS input file - Structural file

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Node Global Coordinate Boundary Condition

Element Material Cross Section data

StructureCoordinatesystem

' Node ID X Y Z Boundary code

NODE 1 .000 .000 .000 1 1 1 1 0 1

NODE 2 10.000 .000 .000 0 1 1 1 0 1

NODE 3 5.000 .000 .000 ' ..

' Elem ID np1 np2 material geom lcoor

BEAM 1 1 3 1 1 1

BEAM 2 3 2 1 1 1

' ..

' VecID dx dy dz

UNITVEC 1 .000 .000 1.000

' ..

' Geom ID Do Thick

PIPE 1 .24070 .0050' Geom ID H T-web W-top T-top W-bot T-botIHPROFIL 5 0.4250 0.0400 0.4250 0.0400 0.8405 0.0250

' ..

' matno. E v yield density therm

MISOIEP 1 210E9 0.3 358E6 7.85E3 1.4E-5

Define nodes and boundary

conditions

Define elements

Define cross section data

Define material properties

Boundary Condition: x,y,z,rx,ry,rz;

0:free; 1:fixed;

Define local z-axis coord. of

beam elements

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COORDINATE SYSTEM

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Local Coordinatex

y

z

1

2

Global Coordinate


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COORDINATE SYSTEM

The global coordinate system is defined as a right-handCartesian

system.

Local coordinate system for the beam element is also defined in right-

handCartesian system : the local x-axis is from the first node (i)

towards the second node (j); the local y- and z-axis are perpendicularto the local x-axis.

UNITVEC in the model file defines the local z-axis in terms of global

coordinates. This vector should not coincide with the local x-axis.

If not defined, the defaultlocal z-axis is parallel to the global (X,Z)plane.

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USFOS input file - Control file

-Static load

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Load case: pressure, CF, etc Usually in structural file

Load Magnitude

Load control parameters: Lfact Minstp nstep etc

Control node displacement Other information: Joint check Saved information

A

P

B

l

1 23

x

y

z


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USFOS input file - Control file

-Static load

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' load case node ID load intensity

NODELOAD 1 3 0.0000E+00 0.0000E+00 -1.0000E+04

' nloads npostp mxpstp mxpdisCUSFOS 10 10 1 1.00

' lcomb lfact mxld nstep minstp1 0.1 1 10 0.1

' ncnodsCNODES 1' nodex idof dfact

3 3 -1 Specify the control displacement of the structure

Load control for static analysis

Different lines refer to the

sequence of load applications

Define a concentrated load

A

P

B

l

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x

y

z


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Running USFOS analysis

If the results are not satisfactory, goback to analysis controlto adjust the

parameters

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Output file

Binary output file:

*.raf file : opened in Xact Text output file:

*.out file : records the structural input and every

incremental steps.

*_status.text file: records the occurrence of yielding,plastic hinges, and member buckling in the analysis.

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.out file OUT file summarizes the structural data both in terms of user definition as well as the

USFOS internal treatment of some of the input (e.g. spring properties). The .OUT also

summarizes the numerical results in each step, as exemplified in the following. The

symbols at the end of element indicates

0: a yield hinge is inserted +: position checked for plasticity

*: plastic hinge removed at element mid-span. Internally, the element is divided into

two sub elements.

0-0-0: plastic tension failure. The axial tension has reached the plastic capacity and amembrane element is inserted.

ELEM ES Node1 Midspan Node2

1 2 -1.00(-1.00) -0.49(-0.36) 0.00( 0.00) +---+---O

2 1 0.00( 0.00) -0.49(-0.36) -1.00(-1.00) O---+---+

-------- G L O B A L R E A C T I O N F O R C E S --------

NODE X-for Y-for Z-for X-mom Y-mom Z-mom

1 -3.806E-10 0.000E+00 1.948E+04 0.000E+00 0.000E+00 0.000E+00

2 0.000E+00 0.000E+00 1.948E+04 0.000E+00 0.000E+00 0.000E+00

TOTAL: -3.806E-10 0.000E+00 3.897E+04 , Vector_Sum XY : 3.806E-1021


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2D frame analysis(1)

1. Input the existingcontrol file and

structure file.

2. Check the structure

file .

3. Press F1 to addcomments to an

existing command.

4. Press F2 to select

and insert another

command.5. For more

information, go to

help\USFOS input

commands and

search. 23

View the model

without running

For command

description


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1. Check the control file .2. Check the control

parameters

3. Press F1 to add

comments.

4. Press F2 to select andinsert another

command.

5. For more information,

go to help\USFOS

input commands andsearch.

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To choose a nodal/element result, click

here and use CTRL + Left click the

member you want to see


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2D frame analysis(4)1. The default joint is

rigid joint.

2. CHJOINT : the capacity

of the tubular joint will

be checked!

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Left empty


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2D frame analysis(5)-MSL

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Due to deformation limitation of MSL

just click OK

Load factor times the basic load

Right click


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HELP

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Help is also available

online athttp://www.usfos.com/,

where you can find:

-Online manuals

-Related publications

-USFOS setupdownload


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Jacket(1)

Wave loading can be interpreted as static loading

or dynamic loading .

For static loading USFOS will step through theactual wave and identify the worst wave

position(the position causing the highest base

shear or overturning moment)

For dynamic loading, some may be implemented:

Marine growth; buoyancy; current

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Jacket(2)

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Identify the worst

wave phase to be

used in the staticpushover analysis.


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Jacket(3)

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1. Find the load level2. Find the baseshear and

overturning moment

usfos introduction

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