hi，when i do time history analysis,i always come into the trouble to time history definition.what spectrum i input isn't the relation the time vs force.can you help me ?

You're not defining a spectrum, but rather a "time pulse". You did set the "analysis type" to "time history" - right?

first， i really thanks for you give me a hand。i make a mistake for defining the curve of time vs force, but there is another question that insufficient memory when coming to time history analysis.

Go to the Configuration Module (the Miscellaneous pane) and allocate more RAM to CAESAR II.

Also, increase your time step and/or reduce your load duration.

i did that，but 256 MB is the largest memory。if i don't reduce time step，i still can't go calculation。what's possible for my model？

is it serious for increasing the time step？is there any rules for load duration ？

thanks for dave！

We suggest ten steps for the highest frequency included in the analysis. For example, if frequency cutoff equals 50 Hz, then time step equals 1/10th of 1/50 seconds. That's 2 ms. Compare that with the "default value" of 0.1 ms. Time step should also be short enough to characterize the load time history.

3q，Dave！i have got your point。do you have any materials of time history analysis for study，which i want to go further study，or you can give me some advices。

thanks a lot ！

Our webinar on the subject should be useful. Find it at:
http://coade.typepad.com/coadeinsider/webinar---caesar-ii/
Fill out the form and we'll send you the link.