Importing pipes network into SSA ignores pipe rules at structures?

[ejcowie]

I have an issue where we create our pipes in pipe networks in C3D to use the rule to terminate at the structure inner wall. We have noticed issues when creating an alignment from network, that the alignment snaps to the downstream structure outlet/start of pipe rather than the centre node of the structure. This issue seems to also happen when exporting the network and importing into SSA which means the true pipe lengths change and the pipe isnt shown on its true alignment.

Does anyone know a fix for this??

[BrianHailey · Accepted solution]

It's been a long time since I've been in SSA but if I recall correctly, the structures in the SSA model are dimensionless. In other words, all the incoming and outgoing pipes connect to the exact same X,Y location. In C3D, that's not necessarily the case. When you export a pipe network that has pipes that don't terminate at the same location (i.e. near the outer walls of the structure) SSA doesn't know how to deal with that so it assumes that the upstream location of the pipe is where the structure is located and adjusts accordingly.

[matt_anderson_pe · Accepted solution]

In this case, the translation between C3D to Hydraflow to SSA causes confusion.

Both C3D and SSA are node-link models, but they speak Hydraflow when C3D sends the model to SSA.   Hydraflow is an upstream node, and a downstream pipe is an element which is why your structures start at pipe start.

It should be meaningless as the pipe length in SSA should be the pipe length in C3D as SSA supports a more conceptual view of the network.

[ejcowie]

Hi @matt_anderson_pe  and @BrianHailey 

Thanks for the responses, that makes sense regarding the programing only utilising the upstream node and pipe. Funny that its also the same way C3D potentially creates alignments from network parts.

I played around a bit more and found if I do an XML export from C3D to SSA the central nodes of the structures line up as originally intended and the pipe lengths differ slightly from the first export (.stm) although the xml is more accurate as a true 3d length with the C3D model.

If I continue with the XML method, do you see it causing any issues down the track with importing back into C3D etc?

[BrianHailey]

If your import settings are all set correctly, I don't think you'll run into any additional problems by using the LandXML option.

[matt_anderson_pe]

The only issue will be round trip.  The Hydraflow tool knows your part family, LandXML will not.