Dividing the truss member into compressional, tensional and null members?

I am using a method made by Jacek Jaskólski to "divide" my space truss members into compressional, tensional, and null members.
But for some reason, all I get are null members.

I want my space frame to have pinned joints among the members, and I want all of my members to be made of solid (not hollow) circular cross-sections.

Can you please take a look at the definition, and see, where am I wrong?

Thank you.

Attachments:

compression tension null.gh, 44 KB
compression tension null.3dm, 95 KB

Replies to This Discussion

Permalink Reply by Robert Vier on August 15, 2012 at 3:36am

hey,

sorry i already looked at your definition back then, but forgot to post :)

i think you did fine, without any modification i am getting this:

are you using a current karamba-version? i am using a WIP-version, maybe the last one also was broken in this function ..

but to be sure you should get it from http://www.karamba3d.com

best

Permalink Reply by djordje on August 15, 2012 at 7:47am

Hi Robert,

I am using Karamba 0.9.007. and Grasshopper 0.8.0066.

I downloaded and installed the newest version of Karamba karamba3d 0.9.084 FREE (32 bit)

(from http://www.karamba3d.com like you told me)

And got the same result as you did. Suddenly the definition started working. Although I got this error message when I opened the compression tension null.gh file:

Message log start (chronological):
--------------------------------------------------------------------------------

Plugin version: 0.8.0066

Input parameter chunk is missing. Archive is corrupt.

Output parameter chunk is missing. Archive is corrupt.

Output parameter chunk is missing. Archive is corrupt.

Output parameter chunk is missing. Archive is corrupt.

Why is that?

Can I dare to ask you few more questions?

2) I want all of my members to be made of solid (not hollow) circular cross-sections.

Does that mean that my diameter and thickness need to have the same values? Like this:

3) I have wind load from 8 directions. Is there a way in Karamba to create load groups and choose the one with the most extreme values (group that will be used as the most relevant one for dimensioning)?

Thank you.

Permalink Reply by Robert Vier on August 15, 2012 at 8:37am

The message on opening the definition is due to the version-gap. if anything doesn't work properly, try replacing your karamba-components within the definition with the new ones, otherwise it is fine.

at the moment there is not dedicated support of load-combinations or -groups in karamba (it might come.eventually), but in any case you can define load cases. every component will then give you a differentiation of the model's values/characteristics under the respective loads in a load case.

further, if you want to create actual load combinations with different weighting of different loads, you have to do that manually and combine the different loads factored into separate load cases - i just did that and can provide some screens or partial definitions if you need it.

best

Permalink Reply by djordje on August 15, 2012 at 9:10am

If I understood you correctly, I would need to define the same load case number for particular load components, in order for them to belong to the same load case?

For example I will define "0" as the "LCase" input of following components:

Gravity, MLoad (self weight of cladding), MLoad (snow), MLoad (wind in x direction).

Then I will define "1" as the "LCase" input of following components:

Gravity, MLoad (self weight of cladding), MLoad (wind in -x direction).

And so on and so, but every time including the Gravity, MLoad (self weight of cladding) as permanent load and just changing the other variable loads.

Is that it?

Yes I would like to take a look at those screens and partial definitions please.

Thank you.

Permalink Reply by Robert Vier on August 15, 2012 at 9:29am

yes it is!

if you define 'LCase' with '-1' it is applied for every load case in the model.

you can also feed in a list of numbers if you want a specific load in more than one load case

my gh keeps crashing when i try to take a hi-res screenshot of my definition .. maybe later!

Permalink Reply by djordje on August 15, 2012 at 9:32am

Ok, later. I hope you will find solution for that crashing problem.

Robert, and what about this:

"I want all of my members to be made of solid (not hollow) circular cross-sections.

Does that mean that my diameter and thickness need to have the same values? Like this:

Permalink Reply by Robert Vier on August 15, 2012 at 9:33am

thickness of a full pipe is half the diameter = the radius

Permalink Reply by djordje on August 15, 2012 at 10:27am

Thank you.

By the way, until you manage to post those examples, can I ask one more thing?

It seems that "Mat" (Material) input has been removed from "Modify Beam" in the newest version:

version karamba 0.9.007 :

version karamba 0.9.084 free :

I noticed that instead, this input has been added to an "Assemble" component in newest version.

The problem is that, when I connect my "MatProps" (Material Properties) output this this "Mat" input of Assemble, it appears that now I have two types of Materials. Take a look:

Why is that?

Attachments:

compression tension null.gh, 48 KB

Permalink Reply by Robert Vier on August 15, 2012 at 10:33am

because the standard- material, -crosssection etc. always remains in the model.

if you dont specify a beam id, the material won't be applied i'm afraid (try if it is, maybe if you dont specify any ids at all, it takes it for every member)

Permalink Reply by djordje on August 15, 2012 at 10:54am

ok. It seems that default material is very similar to mine - S235. But in case I would like to use different material than now, then I would have a problem.

So if I apply my custom made material to all the beams in the model, that will somehow exclude the default material:

How can I check if this is true (applying my custom made material to all the beams in the model, will exclude the default material)?

Permalink Reply by Robert Vier on August 15, 2012 at 11:28am

i suggest reading the manual / looking at some examples on http://www.karamba3d.com

but anyway, when you create beams with 'line to beam' you can specify a beamID for either all of them, or each of them (by supplying a corresponding list - that will be blown up to the size of the line-list with its last element in case it is shorter = normal grasshopper list matching behaviour).

for cross-sections, materials etc you can then specify the id to which they should apply - refer to the given beamID then

cheers

Permalink Reply by Robert Vier on August 15, 2012 at 11:29am

you can disassemble your model, beams, crosssections and there you'll find the material it actually has got assigned