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Verification of cantilever beam analysis in STAAD

September 23, 2014, 12:16 am
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Never having used STAAD for modal analysis before, I referred to Example 15 of the STAAD verification manual which demonstrates how the natural frequency of a simply supported beam . 

For my requirement , I first I attempted to model a simple cantilever beam in STAAD so I could compare the results with manually calculated values. 

For information my input file is shown along the  message.

 I modelled the beam with the section properties and material properties as below

Ax & Az = 0.56m2 

Ixx=Izz = 1.30415 m4

E=205KN/mm2

l = 22m

POISSON 0.3
DENSITY 325.3 kN/m3

I divided the beam up with a series of node points to ensure the mass of the beam was uniformly distributed .

I fully restrained the beam at one end and all other intermediate nodes were free.

 I get the following results: -

Mode

Natural frequency, Hz

(Manual analysis)

Natural frequency, Hz

(STAAD analysis, basic)

1

4.43

4.393

2

27.79

27.479

3

77.79

28.313

4

152.44

76.806

5

84.819

I am looking for an explanation on following issues

1. In analysis by STAAD i am getting only 5 modes of frequency .How to increase the number modes? 

( i tried increasing cutoff modes also tried increasing number of nodes but no change in result)

2. Mode shape 3 (28.313 Hz) & 5 (84.819) given by STAAD analysis is the axial mode. How to avoid the axial modes in analysis.

Input file :

STAAD PLANE
START JOB INFORMATION
ENGINEER DATE 09-Sep-14
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 0 22 0; 3 0 11 0; 4 0 5.5 0; 5 0 16.5 0; 6 0 2.75 0; 7 0 8.25 0;
8 0 13.75 0; 9 0 19.25 0; 10 0 3.66667 0; 11 0 4.58333 0; 12 0 0.916667 0;
13 0 1.83333 0; 14 0 6.41667 0; 15 0 7.33333 0; 16 0 9.16667 0; 17 0 10.0833 0;
18 0 11.9167 0; 19 0 12.8333 0; 20 0 14.6667 0; 21 0 15.5833 0; 22 0 17.4167 0;
23 0 18.3333 0; 24 0 20.1667 0; 25 0 21.0833 0;
MEMBER INCIDENCES
1 1 12; 2 3 18; 3 4 14; 4 5 22; 5 6 10; 6 7 16; 7 8 20; 8 9 24; 9 10 11;
10 11 4; 11 12 13; 12 13 6; 13 14 15; 14 15 7; 15 16 17; 16 17 3; 17 18 19;
18 19 8; 19 20 21; 20 21 5; 21 22 23; 22 23 9; 23 24 25; 24 25 2;
DEFINE MATERIAL START
ISOTROPIC STEEL1
E 2.06e+008
POISSON 0.3
DENSITY 325.3
ALPHA 1.2e-005
DAMP 0.03
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
1 TO 24 PRIS AX 0.56 AZ 0.56 IX 1.30415 IZ 1.30415
CONSTANTS
MATERIAL STEEL1 ALL
CUT OFF MODE SHAPE 20
SUPPORTS
1 FIXED
LOAD 1
SELFWEIGHT X -1
SELFWEIGHT Y -1
MODAL CALCULATION REQUESTED
PERFORM ANALYSIS
PERFORM ANALYSIS PRINT MODE SHAPES
FINISH

I would appreciate any assistance anyone could give me with this. 

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RAM Concrete and EC2 Notional Inclination of a Structure

September 23, 2014, 1:57 am
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Hello,

Eurocode 2 requires the designer to consider the performance of the frame through the application of a notional inclination of the frame under gravity actions.

This is not dissimilar to the notional horizontal force principal in BS8110.

RAM Frame allows me to add a set of notional horizontal load cases for BS8110 but I cannot see the equivalent for EC2.

Does anyone know how this is handled within RAM?

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Section Wizard cross section IX and Iy Problem

September 23, 2014, 2:12 am
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Dear Sir,

while I Created a plate element as 900x30 in section wizard its show Iy-2.025e6mm^4  Iz- 1.825e9mm^4. But if we rotate the orientation of 30x900 again it shows the same value of Iy and Iz. How did I get the correct Iy & Iz value when I rotate. 

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Section Wizard Property problem

September 23, 2014, 2:14 am
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Dear Sir,

while I Created a plate element as 900x30 in section wizard its show Iy-2.025e6mm^4  Iz- 1.825e9mm^4. But if we rotate the orientation of 30x900 again it shows the same value of Iy and Iz. How did I get the correct Iy & Iz value when I rotate. 

Regards

Dhina

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RE: Section Wizard Property problem

September 23, 2014, 6:01 am
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The principal axes in Section Wizard are denoted using the alphabets "U" and "V". In most cases, "U" is the principal major axis, "V" is the principal minor axis. This is the case regardless of how the section is oriented. There is no Beta Angle concept within Section Wizard.

The principal axes in STAAD are denoted using the variables "Y" and "Z". These are the local "Y" and "Z" axes of the cross section (not to be confused with the global Y and Z axis system). Except for the single "ST" angle, in most cases "Y" is the minor axis, "Z" is the major axis.

When you export a file from Section Wizard to STAAD's User Provided Table file,

a) the variables associated with the "U" axis are written into that file as "Z" axis variables

b) the variables associated with the "V" axis are written into that file as "Y" axis variables

In other words, "U" is mapped to "Z" and "V" is mapped to "Y". As mentioned earlier, this is the case regardless of how the section is oriented in Section Wizard.

Hence, if the orientation of that section does not look right in STAAD, you need to apply a BETA angle to it inside the STAAD Modeling mode.

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RE: Section Wizard cross section IX and Iy Problem

September 23, 2014, 6:03 am
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RE: ISM

September 23, 2014, 10:35 am
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Hey Steve

Yeah I was successful in installing structural synchronizer. It didn't give any errors either.  N modestas I'm not sure if struclink is installed on my system! The installed applications doesn't show that! I'm assuming it's not done. N guys thanks for the response.

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Custom templates in RAM Elements

September 23, 2014, 10:49 am
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Does anybody have any experience creating custom templates in Elements? I've been able to edit a tpl file and generate lines between selected nodes, but I would like to be able to have the template generate nodes at specific increments and then connect those new nodes together with members, if that's possible.The only reference material I've found on template syntax is Chapter 17 of the Elements manual, but looking at the existing template files indicates there are terms not included in that chapter. If anybody is aware of another source that might list all of the available commands/reserved words, or if anyone has some tips for someone starting out on making new templates, I'd sure appreciate it. Thanks!

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RE: RAM Concrete and EC2 Notional Inclination of a Structure

September 23, 2014, 11:20 am
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RAM Frame doesn't have the Notional Load generator explicitly for EC like it does for some of the other codes, but you can still have it generate Notional Loads to your specification. You first need to calculate the fraction of the gravity load that needs to be applied horizontally, based on EN 1992-1-1 Clause 5.2. This fraction is Theta_I in that clause. You can then specify this set of notional loads using the Loads - Load Cases command: select Notional as the Type, and select User Defined Story Forces from that drop down list.

Note that the Load Combo generator for EC doesn't not include Notional Loads. This means you will need to create user-specified Load Combinations that include the Notional Loads. Alternatively you can edit the EC load combo template to include the Notional Loads so that the combos with Notional Loads will be automatically generated. If you edit the existing template file (RamConcEC2.cmb) be sure to save it with a new file name and be sure to change the "Name" inside of the file so that it is distinguishable from the original; see RamConcBS8110.cmb as an example of how to add Notional Load cases to the load combo templates. For more information on editing the load combo templates see the RAM Structural System Load Combination Generator manual (RAMLoadCombinationGenerator.pdf), located in the Manuals directory.

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Truss member failed in combined bending & axial in STAAD pro steel design AISC 360-10 !!!!!!!!!!!!!!!!

September 23, 2014, 1:29 pm
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Hi STAAD team,

Please can you describe why is that happened, member defined as truss and output shows 0 moment in both direction, applied load in less than allowable, STAAD shows fail according to H1-1a.

see Attachment

I have another issue that came with STAAD in current and previous update, When I have a model and I want to add later any new beam with new section, the member definition go below the regular place in the file and separate from that originally defined sections, typically after seismic load and before dead load (as seismic define first in STAAD), when run the problem the software comes up with error as it think there is a missing definition for some members. I informed you about this issue previously for the last three updated version you post but no action from your side !!!!!!!!!!!! why all previous versions where good only while now you can't solve that ??????????????????????????????

 

 

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Training hours required to design in STAAD.Pro

September 23, 2014, 2:11 pm
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How many training hours -As in Learn Server- Would it take me to master Steel Design in STAAD.Pro, assuming that all fundamental courses were taken?

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RE: STAAD Pro v8i SS5 - Error Section Properties Not Entered for Member

September 23, 2014, 2:39 pm
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This is the issue I found since they issue SS4, the new added member goes after load input away from the member definition when you open STAAD editor, and when you run the software it will not see that definition when read member and stop with error. STAAD pro guys non responsive to such issues as I already post it more than a year ago. And they even not answer why such problem not exists in previous SS3, 2,...STAAD19 when I started use it.

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STAAD Pro v8i SS5 - Error Section Properties Not Entered for Member

July 3, 2014, 10:46 pm
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We just recently installed SS5 for Staad.Pro v8i. (20.07.10.41)

However, it seems that there is a bug in the new version.

We try to select and assign a new member properties in Modeling and then run the analysis (or Ctrl + F5). After the analysis, we always see this **ERROR** SECTION PROPERTIES NOT ENTERED FOR A MEMBER. But if to be check the missing property, no entity with missing property is found.

Then we tried to change and assign a new member properties by using the STAAD EDITOR, wherein manually input was done to change the member property. Again, we run the analysis, and this time Zero (0) Errors and Zero (0) Warnings.

Can anyone help us why we keep receiving "errors" after analysis when we change/select member properties in Modeling?

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Explain this for me please

September 23, 2014, 8:17 pm
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hello

i am attaching a file which is part of the output file from staad pro

can someone explain me what the stress terms on the upper right hand side are


and the reason why the beam is failing

thanking u in advance

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RE: Load on circular Surface.

September 23, 2014, 8:46 pm
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 **NOTE-Tension/Compression converged after  6 iterations, Case=    1 , good day sir I got same problem what should I do on this to elemenate this notes which I'm not comfortable with please enlighten me...

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RE: Verification of cantilever beam analysis in STAAD

September 23, 2014, 9:00 pm
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Following is my input file data:

STAAD PLANE

START JOB INFORMATION

ENGINEER DATE 09-Sep-14

END JOB INFORMATION

INPUT WIDTH 79

UNIT METER KN

JOINT COORDINATES

1 0 0 0; 2 0 22 0; 3 0 11 0; 4 0 5.5 0; 5 0 16.5 0; 6 0 2.75 0; 7 0 8.25 0;

8 0 13.75 0; 9 0 19.25 0; 10 0 3.66667 0; 11 0 4.58333 0; 12 0 0.916667 0;

13 0 1.83333 0; 14 0 6.41667 0; 15 0 7.33333 0; 16 0 9.16667 0; 17 0 10.0833 0;

18 0 11.9167 0; 19 0 12.8333 0; 20 0 14.6667 0; 21 0 15.5833 0; 22 0 17.4167 0;

23 0 18.3333 0; 24 0 20.1667 0; 25 0 21.0833 0;

MEMBER INCIDENCES

1 1 12; 2 3 18; 3 4 14; 4 5 22; 5 6 10; 6 7 16; 7 8 20; 8 9 24; 9 10 11;

10 11 4; 11 12 13; 12 13 6; 13 14 15; 14 15 7; 15 16 17; 16 17 3; 17 18 19;

18 19 8; 19 20 21; 20 21 5; 21 22 23; 22 23 9; 23 24 25; 24 25 2;

DEFINE MATERIAL START

ISOTROPIC STEEL1

E 2.06e+008

POISSON 0.3

DENSITY 325.3

ALPHA 1.2e-005

DAMP 0.03

END DEFINE MATERIAL

MEMBER PROPERTY AMERICAN

1 TO 24 PRIS AX 0.56 AZ 0.56 IX 1.30415 IZ 1.30415

CONSTANTS

MATERIAL STEEL1 ALL

CUT OFF FREQUENCY 20000

SUPPORTS

1 FIXED

LOAD 1

SELFWEIGHT X -1

MODAL CALCULATION REQUESTED

PERFORM ANALYSIS

PERFORM ANALYSIS PRINT MODE SHAPES

FINISH

Whether ths is sufficient ?

How can i send model ... I not getting the file attachment option in reply editor.

----------------------------------------------------------------------------------------------------------------------------------

Also i need to understand how the mass distribution is made in STAAD?

(i.e I am dividing the beam in to several nodes whether it is equally distributed between nodes?)

How Can i see the mass distribution values in STAAD?

 
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RE: ISM

September 23, 2014, 11:50 pm
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Try to run the installation .exe file of STAAD.Pro. This should check if StrucLink is installed and if not, it should install StrucLink. See if you can create ISM repositories then. By the way, the latest STAAD.Pro version is build 20.07.10.64, so you may want to install this version.

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RE: Verification of cantilever beam analysis in STAAD

September 23, 2014, 11:59 pm
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You need to use command CUT OFF MODE SHAPE together with command CUT OFF FEQUENCY. I.e.

CUT OFF MODE SHAPE 20

CUT OFF FREQUENCY 10000

Please read chapter 1.18.3.2 Mass Modeling in the Technical Reference manual for more information about mass modeling in STAAD.Pro.

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RE: Verification of cantilever beam analysis in STAAD

September 24, 2014, 12:33 am
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RE: Load on circular Surface.

September 24, 2014, 3:01 am
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MZC_ENGR,

If the model contains any of the following data, it could trigger that Note.

a) MEMBER TENSION

b) MEMBER COMPRESSION

c) SPRING TENSION

d) SPRING COMPRESSION

e) PLATE MAT with the COMPRESSION option

f) ELASTIC MAT with the COMPRESSION option

In all these cases, the program has to use an iterative method to find out which member or support spring should be switched off and which ones need to be treated as active. If the components of the structure that are active at the start of an iteration are the same as those at the conclusion of that iteration, convergence is said to have been attained.

The message is reported as a Note because it enables us to understand how many iterations it took to attain convergence for a load case. It is not indicative of anything wrong.

While stabilizing load cases like gravity alone can be solved usually in just one iteration, when they are combined with destabilizing load cases like seismic or wind, more than one iteration may be needed.

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