Spring Design Requirements - CAESAR II - Help

CAESAR II Users Guide

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CAESAR II
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CAESAR II Version
12

CAESAR II selects a rigid rod if the vertical thermal growth at the hanger location is less than the value of Rigid Support Displacement Criteria and a constant support if the vertical thermal growth is greater than the value of Maximum Allowed Travel Limit. Otherwise, the software selects the smallest single spring that satisfies all design requirements provided in the hanger design data.

The spring design requirements are:

  1. The expected installation load (i.e., cold, sustained, restrained, or weight) and the expected operating load (i.e., hot or displacement) must be within the working range of the spring. The software calculates the hot and cold loads for each thermal operating case included in the analysis by your specified values for No. of Hanger Design Operating Load Cases and Multiple Load Case Design Option.

  2. The absolute value of the change in the load (the product of the travel and the selected spring rate) divided by the design load must be less than the Allowable Load Variation (%) value. The default variation is 25%.

    MSS SP-69 defines load variation as the ratio of the change in the load and the operating load. If you select Cold Load design, the software uses the theoretical cold load as the design load instead of the operating load.

  3. If you specify Available Space (neg. for can), then the space must be greater than the basic height of the selected spring. Positive values are compared with hanger height and negative values are compared with spring can height.

If the software cannot find a single spring that satisfies the design requirements, it searches for two identical springs that will each carry half the load. If the software cannot find any springs that satisfies the design requirements, it recommends a constant effort support for the location.