Incremental Dynamic analysis

[mattia86]

Hi, I have to do an analysis of Ida. What is the procedure to insert a accelerogram? I did select file, I selected a text file but I get the following problem: "Times values should be in ascending order".
The values of the time, however, are already in ascending order.
Than, what are "first line" and "last line"? And because the column load factors puts equal to 2?
You have to send me some examples of nonlinear dynamic analysis for guidance?
Thanks

[huffte]

Hi mattia86.

In waht format is your text file? It needs to be one time value and one acceleration value per line. The "LF Column" is really the acceleration column when reading in an accelerogram. So, for example, the first few lines of one of my files are:

Time [sec] Acceleration [g]
0.0000000000 0.0037964810
0.0050000000 0.0051221020
0.0100000000 0.0067958450
0.0150000000 0.0080236540
0.0200000000 0.0082233730
0.0250000000 0.0083216940
0.0300000000 0.0084165910
0.0350000000 0.0085034480
0.0400000000 0.0085827560
0.0450000000 0.0086737560
0.0500000000 0.0087814920
0.0550000000 0.0088936260
.....
.....

I would first select the "Time History Curves" tab.
Then I would select the "Load" button (not the "Create" button).
I would specify: Time Column = 1, LF Column = 2, first line = 2

Since the above accelerations are in g's, and since I have acceleration units set to in/s/s, then when I specify the acceleration load applied to the structure base nodes, I would specify a multiplier of 386.1 on the load.

I hope this helps a bit.

[mattia86]

Many thanks huffte,I solved.