Drift Recorder Explanation Needed...

[grahamo]

The drift recorder is not clear to me. In the manual, it says:

The drift is taken as the ratio between the prescribed relative displacement and the specified distance between the nodes.

1. So the output file contains a ratio, right?
2. What is the displacement relative to? Is it relative to the previous time step or the initial condition?
3. How would I use this ratio to extract the actual drift in the story?

Thanks in advance.

[silvia]

it is the relative displacement between the specified nodes divided by the distance between the two nodes in the specified direction.