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Re: Frequency shift and cut-off frequency

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Please refer to help section 5.30 Miscellaneous Settings for Dynamic Analysis and the two subsections 5.30.2 Mode Selection and 5.30.1 Cut-Off Frequency, Mode Shapes, or Time

These options are not required. I think most users designing buildings would run the dynamic analysis with default settings and then check that the mode shapes are reasonable (in period and shape) and then confirm sufficient mass participation (most codes require >=90%) before using these options to further constrain the analysis.


linking excel file to staad

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Dear All,

I am posting my excel file in which i have prepared staad input file. The staad input which is generated within excel does not have much variables other than length of the member or say loading.

1) I am able to create input file which it prompts to save the extension. so i will be able to save it in *.std extension.

2) My next step is to create another macro which opens my std file say rw..std and analyse it and save and close then extract bmd and sfd values and store in the existing excel file.

I am to able to reach to step 2 as mentioned.

I request here experts using openstaad and vba to help me create this worksheet.

Please do the needful at the earliest

Re: Frequency shift and cut-off frequency

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By default STAAD considers 6 modes which may not be enough to get you close to 100% mass participation for all models ( most codes require at least 90% participation as Seth mentioned in his post ). So once you run a dynamic analysis, check the mass participation and if it is well below 100%, increase the number of modes to be considered, by using the command SET CUTOFF MODE. You would generally not need to use the SET CUTOFF FREQUENCY very often. By default STAAD outputs modal results for frequencies up to 108 cps. You would only use the CUT OFF FREQ and set it to a value higher than 108, if your structure has high frequency modes and if those are important for the analysis. For buildings or bridges I don’t think you would ever need to do that.  

Vibration/machine loads

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Hello,

How do I include dynamic loads in the basic load cases of STAAD? For example, the vendor data I have for it are the dynamic load in LBS and the vibration frequency in RPM.

Thanks,

Sue

Possible to merge several STAAD.Pro files into one model?

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Is it possible to merge two or more files into one model? This issue is not getting the structures into one file but once they are combined the member references from the imported (copy and paste) structure take on the member reference of the target file. Any thoughts?

Re: Possible to merge several STAAD.Pro files into one model?

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Hello

I have attached a document which may be of some help to you .

Re: linking excel file to staad

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Please help I am in need of this workbook

cannot open RC designer

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Sir,

I can't open RC designer.. After performing analysis, i can click post perform analysis and structural design but i cant open the RC designer.. Is there a possible problem in my design?

 

thanks a lot...


Re: Frequency shift and cut-off frequency

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Thanks but I am still not clear about the real meaning of cut-off frequency and frequency shift in modal analysis...?

Regards,

WH

Re: cannot open RC designer

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What version of Staad are you using? (Help>>About Staad Pro) . Is there any error in the analysis? Is this happening only with a particular model or all models?

Re: Vibration/machine loads

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In STAAD you can define various forms of dynamic loading details of which can be found within section 1.18.3 of Technical Reference (titled Dynamic Analysis). From the input data you mentioned, it seems that you should use the time history load that allows you to input a harmonic function that is typically used to simulate a vibrating equipment sitting on a structure. From within the software, you can go to Help > Contents >  Application Examples > American Examples > Example Problems and take a look at example no 22. You will find the associated STAAD model file within the folder X:\SProV8i\STAAD\Examp\US in your machine, where X represents the drive where STAAD.Pro is installed.

Continuous Arch in RAM Elements

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I'm designing a wooden truss with an arched bottom chord. I'd like for this bottom chord to act as a single member so I can test out of plane buckling over the full unbraced length. Anyone know how to do this? I've attached a picture of my truss:

Re: Continuous Arch in RAM Elements

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You can introduce mode nodes if necessary to make it more truly curved.

You can remove the member hinges if you want to to be a truly continuous member.

But when it comes to bucking, the only thing you can do in Elements is set the L22 axial unbraced length value (or L33 if the section rotated 90 degrees). L22 will default to the member/segment length, so you might have to specifiy a larger value which in-turn reduces the compression capacity of the members. Elements is not going to do any kind of non-linear buckling analysis, however.

Re: cannot open RC designer

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i am using staad pro v8i.. its my first model using staad.. There is no error in the analysis... Is there something I need to do to be able to open the RC designer?? Thanks a lot!!!

Re: Frequency shift and cut-off frequency

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By default, STAAD calculates only those modes whose frequencies are less than or equal to 108 cps. This is what is meant by the default value for the command CUT OFF FREQUENCY.

If you have a model for which you want frequencies higher than 108 cps to be computed, you need to convey to STAAD the higher threshold. For example, if you want modes with frequencies as high as 1000 cps, specify

CUT OFF FREQUENCY 1000

Note that depending on the model, it may not be possible to calculate more than a certain number of modes. The limitations of the mathematical procedures used for calculating modes and frequencies may restrict the number that can be calculated, and the highest computed mode can then still be well below 1000 cps.

I am not aware of a feature called FREQUENCY SHIFT in STAAD.Pro.


Re: cannot open RC designer

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Which code are you looking to use RC designer with? One way to find out if you have a license for that code is a green/red circle alongside that code in the license segment of the opening screen of the program.

Have you checked whether you can perform a design of a concrete beam or a column with that code? In the folder

C:\SProV8i\STAAD\Examp\US

you will find a file named Tut_02_rcframe.std. If you go to the Design-Concrete page on the left side in the modeling mode, you will notice instructions like the following in the view on the right side of the screen.

START CONCRETE DESIGN

CODE ACI

UNIT MMS NEWTON

CLT 25 MEMB 1 TO 5

CLB 30 MEMB 1 TO 5

CLS 25 ALL

FC 25 MEMB 1 TO 5

FYMAIN 415 MEMB 1 TO 5

TRACK 1 ALL

DESIGN BEAM 2 5

DESIGN COLUMN 1 3 4

END CONCRETE DESIGN

Depending on the code you intend to use it with, go into the editor, and change the code from ACI to the desired one (keep a backup of the file before you do so) and then run the analysis. View the output file and ensure that the design has been performed successfully.

If you can't make any progress on this, create a service ticket at

www.bentley.com/serviceticketmanager

and one of the analysts will contact you.

Re: cannot open RC designer

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One more suggestion.

If you are able to get the concrete design to be performed in the batch mode for Tut_02_rcframe.std as I suggested earlier, then, try going into RC Designer using that model. If you encounter the same difficulty as you first stated, then, it may be a licensing or installation-related problem in which case, you may want to contact a STAAD.Pro technical support analyst.

Re: cannot open RC designer

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Thanks a lot... it seems that i did not execute the concrete design yet..

Physical Member and Grouping Members

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Reference: Model described in post  "STAAD Pro v8i Model too Big" and answers by Kria Sathia.

The model had a number of "girde"r beams supporting floor beams and running from column to collumn, These girders were made into Physical Members. Mr. Sathia suggested that the fllor beams were not connected to nodes of the support girders because the Physical Beams had no nodes at intersection point. Inspecting the Command file showed these Physical Beams had nodes at ends only. The program procedure to "break up" the girders into short beams at the ends of the floor beams didn't work. so all beams were manualy replaced between nodes.  This eliminated the the instability warnings.

 Questions

1.  How  to use Physical Members command and get beams to  connect to it at intermediate nodes using the graphical interface?

2. My model has 240 girders. Is there a way to use the "Group" command to to form a Girder with intermediate nodes and not have a group for each girder?

 

Thanks for your help,

Billbe

How to apply Load on curved beam.

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Hello

Please help me to find the staad command to apply a point load on beam when coordinates (x, y, z) of load are known. I need to apply it on a curved beam. Have been tried member load already but its not working positively.

Request you to please guide me to apply load command when coordinates are known.

Regards

Ravi

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