Pipe in boxculvert stress analysis

First of all, I would like to let you know the objective of the subject is not pipe stress analysis result (as in other pipeline/piping software).

I would like to ask for structural analysis related to pipe (pipeline) located in boxculvert. I need an expert opinion regarding how certain the analysis I design for this case in staadpro.

I design a boxculvert made of concrete in rectangle shape (0.5 x 1) m. At the bottom of boxculvert I put a pipe (pipeline) with diameter 0.6 m and weld thickness 0.15 m.

I assign the distributed load on each side of the boxculvert as in reality the boxculvert will accomodate this load. The static analysis result show small displacement on the bottom of boxculvert.

I am wondering to know if this is a good representation to know the reliability of the boxculvert 

Attached is the file. Thank you. 6175.Structure2.std