Technical Discussion of LIQT Interface - CAESAR II - Help

CAESAR II Users Guide

Language
English
Product
CAESAR II
Search by Category
Help
CAESAR II Version
13

Normal piping system operating procedures such as pump start-up and shutdown, valve closure, and unexpected events such as power failure, may produce unsteady pressure-flow conditions. A piping system with rapid pressure-flow variations must be carefully designed to prevent devastating results.

The SAI LIQT package performs the analysis and simulation of the unsteady flow situations for a particular liquid piping system, and generates the piping load time histories for the pressure transient of this particular liquid piping system.

In the dynamic analysis module of CAESAR II, a response spectrum can be generated from the input of time history pulse. However, there are typically too many data points from a time history analysis for you to manually input the data into CAESAR II. The LIQT interface bridges the gap between the SAI LIQT package and the CAESAR II dynamic analysis module.

After the time history loads have been generated by the SAI LIQT package, the CAESAR II LIQT Interface extracts the dynamic pipe forces from the LIQT generated file, and computes the response spectrum. Afterward, the response spectrum can be used as the DLF curve for the dynamic analysis in CAESAR II.

The response spectrum is a plot giving the maximum response of all possible linear one-degree of freedom systems because of a given input, which is a force. The abscissa of the spectrum is the frequency axis, and the ordinate is the maximum response such as the dynamic load factor (DLF). The DLF is the ratio of the dynamic deflection at any time to the deflection which would have resulted from the static application of the load. In cases where the applied load is not constant, the maximum load that occurs at any time during the period of interest is taken.

The dynamic load factor is non-dimensional and independent of the magnitude of load. The following examples illustrate the characteristics of the DLF curve in terms of the magnitude and the duration of the load.