Need help in understanding what Caesar does for Time history analysis. I tried reading thru the manuals but could not get it.

Any help will be appreciated

Can you please expand this question a little? What are you looking for?

This is a rather complex subject, and as such, a complete explanation (sufficient to perform a hand calc or develop your own algorithm) in a post here, or an e-mail is not possible.

If you "Google" the phrase "modal time history" you will find a wealth of information. This is a good one: http://www.saviac.org/74th_Symposium/Training%20Handouts/Scavuzzo.pdf#search=%22%22MODAL%20TIME%20HISTORY%22%22

Thanks Richard for the link. Its quite useful.
To expand my question, I am running the time history analysis for water hammer problem and in order to verify the results I am trying to understand the equations/methodology caesar is applying to converse the results.
Caesar technical reference document extended little help which I could not relate to the theory behind it.

Thanks in advance

For an introduction and summary of what goes on in a Time History analysis, check out the article in Mechanical Engineering News, in the December 1993 issue. The article you want begins on page 9.

For an example of usage, check out the article in Mechanical Engineering News, in the June 1994 issue. The article you want begins on page 8.