There's a good chance that you have a modeling problem and NOT an over stress problem.
The program will provide closely-spaced translational restraints before and after bends in your buried model. These extra restraints will knock out bending as you would expect in a buried line. CAESAR II will automatically add these restraints for those elements which frame (i.e., enter or exit) the bend. As a user, you are responsible for adding these extra restraints at other bearing points (e.g., tees). Unfortunately, your model does not show the full complement of added restraints because the length of the pipe into and out of your bends is too short. I see a few elbows in your model that have nodes explicitly defined at one or both ends of the elbow. For such modeling, it is up to you to tell the program to add these extra restraints on the neighboring elements. Do this by checking the "From End" and/or "To End" meshing checkbox. As an exercise, I suggest you check these boxes for all the contiguous, short runs around your bends. If this resolves your over stress issues, then go back and clean up your buried model.
In the future, be sure to have longer runs into and out of your bends.