Plain GroundMotion
This command is used to construct a plain GroundMotion object. Each GroundMotion object is associated with a number of TimeSeries objects, which define the acceleration, velocity and displacement records for that ground motion. The command is as follows:
| groundMotion $gmTag Plain <-accel $tsTag> <-vel $tsTag> <-disp $tsTag> <-int (IntegratorType intArgs)> <-fact $f> |
where
| $gmTag | unique tag among ground motions in load pattern |
| $tsTag | tag of TimeSeries object created using timeSeries command. |
| integratorType ... | used to generate a numerical integrator. default TRAPEZOIDAL. see NOTES below. |
NOTES:
- The displacements are the ones used in the ImposedMotions to set nodal response.
- If only the acceleration TimeSeries is provided, numerical integration will be used to determine the velocities and displacements.
- For earthquake excitations it is important that the user provide the displacement time history, as the one generated using the trapezoidal method will not provide good results.
- Any combination of the acceleration, velocity and displacement time-series can be specified.
Code Developed by: fmk