Solving only a single structure in a workspace containing multiple structure

[keen_mentee]

Hi,

I am running into a problem while using RISA 3D 17.0. I would really appreciate your suggestions.

I have a cupola that is shipped in site in multiple parts (three) and are attached in the site with bolts. I have modeled all the parts in the same workspace. I want to solve only one part at a time. How can I do that in RISA 3D v17.0. I have attached a picture that could be helpful to understand my issue.
I tried unselecting two part, using "Ctrl+L:lock the unselected part of the model. I do not think is solving my problem. I also tried Modify Propertied>>Member Activation and selected "member is not active". This also did not help with my issue. I would appreciate if anyone could clarify these two functions in RISA as well.

I appreciate your time.
Thank you,

Thank you.

 

[JoshPlumSE]

Select only the parts you DON'T want to solve. Then use the Modify Members tool and change the member "Activation" from Active to "Exclude" or "Inactive".

Exclude means that the member is included in the analysis, but the program won't give any results or code checks.

Inactive means that the member will be completely turned off... like it doesn't exist. This could, result, in a number of instabilities at the joints / nodes though.

 

[keen_mentee]

Hi JoshPlumSE

I tried the Modify Member tool and selected "Member is NOT Active" option. However I did not get my desired output. My apologies for not explaining my problem properly in the main post. My goal is to get the total force on the sub-sections due to area loads(wind X). I need the total force in kips applied to the structure which is equivalent to the area load (ksf) that I applied to the sub-sections. Generally, I do a single load combination solution of that area load only (I have defined a load combination with that area load only) and get the total force (which includes force in all anchors) from Results>>Joint Reaction (By Combination). However, for this particular project as I had many sub-sections, I wanted to do analysis on individual sub section too. So my workspace has three separate structures with same loading(Same Load Combination) duplicated in each sub section. Now when I do the batch solution, it gives me the sum of the duplicate area loads too. When I tried to make the members inactive and run the model, the duplicated area load do not have any member in the plane of some loading and the model does not run. Is there a way I can make a area load temporarily inactive (like for the members) instead of putting a value of zero or deleting it? I wish to get the equivalent force (kips) in each sub-section which corresponds to an area load.

Thank you.

 

[dauwerda]

Is there any reason you can't have three separate models? Just do a save-as and delete out what you don't want.
OR
Have you tried to use the "exclude" feature when looking at results? Once you run the model, select only the model you are interested in and hit the exclude button. I'm not sure if this would give you the results you are looking for or not.

 

[JoshPlumSE]

I think dauwerda has a good idea. The "Excluded" option may be the better way to go.... at least compared to making the member "Inactive"

 

[keen_mentee]

Hi dauwerda and JoshPlumSE,

The reason I wanted to have all the three models in the same workspace is because I have to modify the members (upsize/downsize) many times and I need to check if the individual as well as the entire structure will pass the code limitations. I am using section sets, so its easy to change the section set and have the properties updated in all three sub-sections instead of having to close and re open multiple RISA files. The exclude feature does not help with this exact situation. But I used exclude feature to remove unwanted data in my final report.

Overall, I did a combination of delete, CTRL+Z, CTRL+Y etc. to get around my problem. Thank you for your input. It is very helpful knowing how other people would deal with the same situation.

Also, similar to making member inactive, can I make an area load temporarily inactive instead of having to delete the load just to put it again?

I appreciate your time.

Thank you.

 

[Celt83]

I wish to get the equivalent force (kips) in each sub-section which corresponds to an area load.

Since the node numbers aren't changing can't you setup a spreadsheet to sum the nodal reactions for for each component model? Assume the reactions would be output in node order so should be pretty simply to find the summation ranges for each component.

My Personal Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

Open Source Structural GitHub Group:

https://github.com/open-struct-engineer

 

[dauwerda]

I certainly understand wanting to keep it grouped together for working through the iterative process.

The two ways that come to mind for the load would be either:


Set the load = to 0 in the spreadsheet when you want to exclude it (then back to the actual value when you want it).

Provide 2 sets of load combinations, one set that includes the load and one set that doesn't and only solve the respective combinations that you want.

 

[JoshPlumSE]

Also, similar to making member inactive, can I make an area load temporarily inactive instead of having to delete the load just to put it again?

Not that I know of. However, I might instead choose to have my area loads in different Basic Load Cases. That way, I can carry different Load Combinations depending on which portions of the structure I'm interested in. Let's say this is all Wind Load (load Category WL). Well, I could have BLC's 10 included the WL area loads on the first structure, BLC 11 on the middle one and BLC 12 on the last one.

That way, whenever I run a Load Combination that directly references WL, I get all three. But, if I run a Load Combination that reference BCL#10 instead of WL, then I get only the first structure, etc.