Time History Analysis

[DSB123]

Hi All,
I have a query as to how caesar conducts a Time History analysis of a piping system utilising Hydraulic analysis output from a software package which is converted to a force vs time input. From what I have read in the Caesar guides it appears that the force vs time loading is applied at changes in direction of the piping system. However the guides seem to suggest that the base force vs time information is "amplified" by a frequency vs DLF (Dynamic Load Factor) table. Does this mean that the Hydraulic analysis loads are increased when performing a time history analysis as I beleive to be the case?

Regards

DSB123

 

[richay]

Be careful not mix up time domain analysis (time history) with frequency domain analysis (response spectrum).

You can take your hydraulic data and send it through CAESAR II’s response spectrum generator to develop a DLF vs. frequency response curve. This “INDUCED load multiplier versus frequency” can then be used with the APPLIED load to produce the system response. So here you're performing a "response spectrum analysis" in the fequency domain.

Or...

You can run the load-time results from the hydraulics package directly through CAESAR II’s Time History analysis. Here you're performing a "time history analysis" in the time domain.


The former (response spectrum / frequency domain) is quick and easy and single loads can be applied generally; the latter (time history / time domain) is very specific to the timing but can have several loads interact in time.


Richard Ay
COADE, Inc.