Simple Bottomed Out Spring - CAESAR II - Reference Data

CAESAR II Applications Guide

Reference Data

Spring supports that may bottom out have SPR following a translation direction in the restraint Type box (such as, YSPR for a vertical bottomed-out spring).

When a bottom out spring is entered, the restraint auxiliary screen changes as follows: The Gap value changes to "x" (the permitted travel), and the Mu value changes to F (the initial spring load). The direction of permitted travel is assumed to be opposite to the initial load on the pipe. These definitions are setup to handle vertical springs. Because of this, the "x" and F inputs are always entered as positive as shown in the following example.

Simple bottomed-out spring restraints are used most often to conveniently enter predefined springs into the piping system model. These spring restraints provide a bottoming out capability that occurs when the spring has exceeded its maximum travel limit.

Always enter the stiffness Stif, the allowed travel "x", and the initial load on the spring F, to use the bottomed out spring model. If the travel "x" is not entered, it defaults to zero. If the initial load is not entered it also defaults to zero, and its sign is positive. No hanger should be entered at the same position as a bottomed out spring.

Known information:

  • Theoretical Installed Load = 1023 lb.

  • Spring Rate = 260 lb./in.

  • Largest Load in Hanger Table = 1690 lb.