I have a truss of this kind where a truss is carried by another girder truss, where a joint will have 7 members as shown on attachment below.
Which connection is the perfect connection, bolt or weld and how to design it in Staad Pro?
?
You may have to apply multiple connections at the same joint. Please upload the .std file and indicate the node number.
8508.Structure1.STD
Node number 105 and 116
You've asked the right question. It's all about the connections in this type of structure. There are companies who specialize in this and have spent no telling how much money developing proprietary connections. I'm assuming this is a school project because if you're asking about this for a real job you actually have to construct and you haven't got a least a rudimentary idea of what you are going to do at the connections, you're in for a long hard road.
I suggest searching "space frames" on the internet to get an idea of some connection details, although most pictures are taken from too far away to tell exactly how they did.