ROCK
ROCK, CGX, CGY, CGZ, OMX, OMY, OMZ
Specifies a rocking response spectrum.
-
CGX,CGY,CGZ Global Cartesian X, Y, and Z location of center of rotation about which rocking occurs.
-
OMX,OMY,OMZ Global Cartesian angular components of the rocking.
Notes
Specifies a rocking response spectrum effect in the spectrum (ANTYPE,SPECTR) analysis.
The excitation direction with rocking included is not normalized to one; rather, it scales the
spectrum. For example, consider a node at coordinates (1,1,0),
subject to an excitation in the X direction (SEDX = 1.0 on
SED), and a rocking with center CGX = 1.0,
CGY = CGZ = 0, and angular component
about Z (OMZ = 0.5). The total excitation direction at this node is:
So that half the spectrum input is applied at this node.
For more information on the equations, see Participation Factors and Mode Coefficients.
This command is also valid in PREP7.