Large rotation rods are used to model relatively short rods, where large orthogonal movement of the pipe causes shortening of the restraint along the original line of action.
Large rotation rods can be entered in any direction. The user picks the XROD, YROD, or ZROD from the type list. When CAESAR II detects that a rod is being input, the restraint field is changed: Gap is changed to Len and Mu is changed to Fi. Len is the length of large rotation swing. Fi is the initial load on the restraint if used to model a variable support spring hanger.
Large rotation rods should only be entered where needed. Repeated use where not necessary may cause the system to become unstable during the nonlinear iteration. The system should first be analyzed without the large rotation rods and then large rotation rods added where horizontal movement at support points is greatest. Usually only one rod should be added in an area at a time.
Large rotation is generally considered to become significant when the angle of swing becomes greater than 5 degrees.
Connecting nodes may be used for large rotation rods just like for any other support.