Including the Spring Hanger Stiffness in the Design Algorithm - CAESAR II - Help

CAESAR II Users Guide

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CAESAR II
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CAESAR II Version
12

The operating cases for hanger travel are normally analyzed with no stiffness included at the hanger locations. This is why these cases are traditionally referred to as free thermal cases. However, when the piping system is very flexible, or the selected springs are very stiff, the actual resulting spring loads in the installed condition can vary significantly from the theoretically calculated results. With such a load change, perhaps this shorter, more accurate spring deflection may allow a smaller spring selection. In that case, CAESAR II allows you to include, using an iterative process, the stiffness of the selected springs in the operating cases for hanger travel.

You can set this option for new model through Configure\Setup by changing Include Travel to As Designed. You can also activate this option on the Load Cases Tab (Static Analysis - Load Case Editor Dialog Box) tab by changing the Hanger Stiffness option to As Designed.

Selecting this option could lead to convergence problems. If you use this option, be sure to check the hanger load in the cold case in the field so that it matches the reported hanger Cold Load.

You must always include the hanger preload force set H (the Theoretical Cold Load) in subsequent load cases.

Applying thermal and displacement effects to the live loaded system should make an installed hanger move to the hot, or balanced, load in this operating case.