# 4.8.2. UniformExcitation Pattern¶

pattern('UniformExcitation', patternTag, dir, '-disp', dispSeriesTag, '-vel', velSeriesTag, '-accel', accelSeriesTag, '-vel0', vel0, '-fact', fact)

The UniformExcitation pattern allows the user to apply a uniform excitation to a model acting in a certain direction. The command is as follows:

 patternTag (int) unique tag among load patterns dir (int) direction in which ground motion acts corresponds to translation along the global X axis corresponds to translation along the global Y axis corresponds to translation along the global Z axis corresponds to rotation about the global X axis corresponds to rotation about the global Y axis corresponds to rotation about the global Z axis dispSeriesTag (int) tag of the TimeSeries series defining the displacement history. (optional) velSeriesTag (int) tag of the TimeSeries series defining the velocity history. (optional) accelSeriesTag (int) tag of the TimeSeries series defining the acceleration history. (optional) vel0 (float) the initial velocity (optional, default=0.0) fact (float) constant factor (optional, default=1.0)

Note

1. The responses obtained from the nodes for this type of excitation are RELATIVE values, and not the absolute values obtained from a multi-support case.
2. must set one of the disp, vel or accel time series