What value of scale factor should be used for the definition of the response spectrum load case?
When you define the response spectrum curve, the acceleration is typically entered as a fraction of gravitational acceleration (the gravitational acceleration is 9.81 m/sec/sec or 32.2 ft/sec/sec). The scale factor should be entered such that the response spectra values multiplied by the scale factor will be equal to the desired acceleration in current units. In other words, if the acceleration for your response spectrum function is entered as a fraction of gravitational acceleration and the current length units are ft, then scale factor of 32.2 should be used for U1, U2 and U3.
