A question in ANSYS

[jsyz]

I am doing a seismic analysis with ansys.
After 400 steps(substeps), .rst file in ansys reaches
4. GBytes, then, ansys is closed automatically.
I tried several times, and the results are the same.
ansys is closed as soon as .rst reaches 4.Gbytes.

What should I do if I want more steps than 400?
How can I get over the limit size of the file?

The version of my ansys is 5.7.
The OS is Windows 2000.

 

[Qshake]

You will need to post this in the Finite Element Analysis Engineering forum. In that forum there are engineers experienced in a wide variety of FEA programs like ABAQUS, ANSYS, STRESSCHECK and others.