From what I understand a typical interactive truss system would need substantial calculations since every component affects the entire system. I think you could arbitrarily stop at a given number of iterations at cost of accuracy in the simulation, but I don't know if that's the approach these games use (bridge building games are an example of truss systems). On the other hand, games like Dig or Die have a quite complex structural system that also takes torque into account (I believe) and compression and is very fast and works on very extensive systems. I guess the basic calculations could be similar, but if not I'm interested in both approaches.
Do you guys know how these are made? Do they have an arbitrary limitation or do they use a different algorithm altogether? Also, I guess whatever you guys come up with can be applied to 3D systems but if not or if it's not obvious please at least give a clue on how you could use it for 3D since I'm interested in this for both 2D and 3D games.
I know I'm not supposed to thanks here but I find unfair not to at least thank you for your time in advance, I hope this paragraph don't get removed.
EDIT: If I were to make a guess I'd say Dig or Die stores vectors for each block and then run an iterative algorithm up to a point that the extra accuracy in the simulation is meaningless for the limits of the system (for example, the system would be too large to not collapse anyway), so it's limited by a semi-arbitrary (because it's based on application) number of iterations. But I could be wrong.