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# Nonlinear Analysis

## Nonlinear Analysis

(OP)
Hello...
I would like to do a nonlinear analysis in GT STRUDL...
Can anyone help me in it? If you have tutorial or things like that, I would love it =]

Thanks.

### RE: Nonlinear Analysis

It is fairly easy. You declare the geometric nonlinear command and then preform a nonlinear analysis. My manual is at work, but the procedure is in the user's manual.

_____________________________________
I have been called "A storehouse of worthless information" many times.

### RE: Nonlinear Analysis

(OP)
Thanks man... But can you explain me what means "declare the geometric nonlinear command"?

### RE: Nonlinear Analysis

The P-Delta is the most common nonlinear condition where flexible structures deflect and the vertical load now creates a moment at the base. You can also have nonlinear springs to model soil or a tension only or compression only member.

The drop down menu under Modeling-> Nonlinear Effects has several options.

Here are a few commands that I use:

NONLINEAR EFFECTS
GEOMETRY MEMBERS EXISTING
MAXIMUM NUMBER OF ITERATIONS 25
NONLINEAR ANALYSIS

PARAMETERS
CODE AISC13 All Members
CODETOL 0.0 ALL MEMBERS
SUMMARY YES All Members
STEELGRD A36 All Members

_____________________________________
I have been called "A storehouse of worthless information" many times.

### RE: Nonlinear Analysis

You can download the free Student Version of GTStrudl at the Georgia Tech web site which includes some documentation (probably not the entire manual set). There is a limit on the number of joints and members but otherwise it is fully functional.

_____________________________________
I have been called "A storehouse of worthless information" many times.

### RE: Nonlinear Analysis

(OP)
I have the GT STRUDL in my job without limitations, but I cannot understand very well the manuals... Don't you have any tutorial for me? Or Can you explain me what means every line of what you said?

Thank you a lot for your help.

### RE: Nonlinear Analysis

OK, I see. You can probably work through the examples of nonlinear analysis included with the installation. I have copied the example below incase you did not do a full install with examples. If you don't have the examples, I would install the full version with all examples.

You might consider taking the GTStrudl basic and advanced course when they are given in Atlanta. The summer courses were given in August and the spring course is taught during spring break at Georgia Tech next year.

*TITLE 'EXNL01 - HIGHLY NONLINEAR COMPRESSION-ONLY TEST'
STRUDL 'EXNL01' 'HIGHLY NONLINEAR COMPRESSION-ONLY TEST'
***********************************************************************
$* ** PROBLEM DESCRIPTION: Sample problem for Nonlinear Analysis.$***********************************************************************
$PRINT GEN OFF UNITS FEET POUNDS DEGREES GEN 2 JOI ID 1 100 X -8.916,-1 Y -14.5 MOD 19 ID 1 Y 0.97 JOINT COORD 1001 -2.83 4.907 1002 2.83 4.907 GEN 2 JOINTS CYL Z ID 21 100 R 6.083 1 TH 180 LZ 0 OFFSET 1001 MOD 6 ID 1 TH -10 GEN 2 JOI CYL Z ID 28 100 R 11.75 1 TH 115 LZ 0 MOD 11 ID 1 TH -5 GEN 2 JOI CYL Z ID 40 100 R 6.083 1 TH 50 LZ 0 OFFSET 1002 MOD 5 ID 1 TH -10 GEN 2 JOI ID 46 100 X 8.916 1 Y 3.937 MOD 19 ID 1 Y -0.97$
TYPE PLANE FRAME
GEN 64 MEMBS ID 1 1 FROM 1 1 TO 2 1
TYPE PLANE TRUSS
GEN 63 MEMBS ID 101 1 FROM 102 1 TO 2 1
STATUS SUPPORT JOI 1 65 102 TO 164
JOINT RELEASES
1 65 MOM Z
DELETIONS
JOINTS 101 165
INACTIVE JOINTS 1001 1002
UNITS INCHES
PRINT JOINT COORDINATES
UNITS INCHES
CONSTANTS
E 3.6E6 MEMBERS 1 TO 64
E 1.E6 MEMBERS 101 TO 163
MEMBER DIMENSIONS
1 TO 64 RECT B 12 H 10
MEMBER PROP PRIS
101 TO 120 144 TO 163 AX 139.68
121 TO 143 AX 152.88
 PLOT PROJECTION
$LOADING 1 'UNIFORM LOAD OF 1 KIP/FT' MEMBER LOADS 21 TO 44 FORCE Y GLO UNIW -83.33 LOADING 2 'TEXT LOAD TO MATCH ANSYS RESULTS' JOINT LOADS 21 TO 45 FORCE Y -713.2$ = 17830 LBS
$LOAD LIST 2 NONLINEAR EFFECTS COMPRESSION ONLY MEMBERS 101 TO 163 MAXIMUM NUMBER OF CYCLES 1 CONVERGENCE TOLERANCE EQUIL 0.00001 NONLINEAR ANALYSIS REDUCE BAND LIST LOADS DISPL NONLINEAR ANALYSIS CONT LIST LOADS DISPL NONLINEAR ANALYSIS CONTINUE MAXIMUM NUMBER OF CYCLES 20 NONLINEAR ANALYSIS CONTINUE OUTPUT DECIMAL 4 OUTPUT ORDERED LIST DISPLACEMENTS LIST LOADS LIST REACTIONS LIST FORCES$
CONVERGENCE TOLERANCE DISPL 0.00001
MAXIMUM NUMBER OF CYCLES 25
NONLINEAR ANALYSIS
LIST DISPLACEMENTS
LIST REACTIONS
LIST FORCES

_____________________________________
I have been called "A storehouse of worthless information" many times.

### RE: Nonlinear Analysis

(OP)
Where did you find this example? I would like to see it. I live in brazil, hehe, so it's difficult for moving abroad =P
Can't you save it in a pdf file and send me?
Thank you a lot man !

### RE: Nonlinear Analysis

You should be able to copy the text from the message above and save it as a XXX.GTI file and run it in GTSTRUDL. All the example files are included when you install GTSTRUDL, but you must do a custom install and not the standard. When you install the program it will ask you to select which way you want. Select custom and select the examples and the Macros.

The program comes with several example files that will show you what is possible with the software.

I always attend the User's Group meeting in June and people come from as far as Sri Lanka and Russia. A group from South Korea used to attend. Our last meeting was in Seattle and I believe we will be in Charlotte, NC next year.

_____________________________________
I have been called "A storehouse of worthless information" many times.

### RE: Nonlinear Analysis

If your company is on the usual maintenance contract with Georgia Tech, you can call or eMail the CASE center and they should be able to help you with a tutorial on how to use the nonlinear features. The biggest difference between the Stiffness Analysis and the nonlinear analysis is the load combinations that you usually use. For NLA, you will use the Form Load.

_____________________________________
I have been called "A storehouse of worthless information" many times.

### RE: Nonlinear Analysis

As a user of GTSTRUDL software, I find it to be extremely helpful to contact GTSTRUDL technical support at the CASE Center. The contact information for the CASE Center can be found by selecting: Help > About GTStrudl

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