Hello,

I am trying to a natural gas pipeline analysis. The line is starting with hot tap tee to pig launcher and thereafter goes into the soil. I made g vector zero under soil but failed under soil altough zero vector. Failed load cases are L36, L37, L39, L40.

Disable U1, U2, etc for the buried pipe. They're not applicable, because the buried piping gets moved in bulk with the earth.

CAESAR doesn't actually know the pipe is buried - it doesn't know anything beyond the pipe being weightless and held by springs.

As the buried piping actually shifts north during a seismic event, the movement of the unburied pipe, relative to the buried pipe, is to the south. And that's what you're simulating.

Mr. Fletcher i disabled u1, u2, u3 vectors zero for the buried pipes. I think seismic loads in buried parts should be zero because of zero u vectors. But not zero and some points are failed.