I want simulate moving pig train with weight 4 tonnes moving by 4 m\min.
anyone can help me in this input?

Choooo woooooooooo..............

Sounds like a time force dynamic analysis mess of huge proportions... fortuanately I am not involved with this!!!!!

Ahmed,

I am waiting for all your files so I can review your input and make some suggestions. As I said to you in e-mail, this is best handled as a Time History analysis similar to a slug flow problem. But your velocity of 4m/min is so slow (force-time profiles are input in milliseconds in Caesar, not minutes) that you may be able to do this statically instead. Apply the force at a given node, include F1 in a second OPE case, subtract the standard OPE case from the one containing the F1, and then add that result to SUS and compare it as an OCC case. You would want to do this a few times so that you apply this force at the different bend nodes in your system. You might also want to apply this as a weight in the mid-spans of your piping. If your piping system survives this pseudo-static analysis it is not going to be a problem dynamically.