DSUM
DSUM, SIGNIF, Label, TD, ForceType
Specifies the double sum mode combination method.
SIGNIFCombine only those modes whose significance level exceeds the
SIGNIFthreshold. For single-point, multi-point, or DDAM response spectrum (Spectype= SPRS, MPRS, or DDAM on SPOPT), the significance level of a mode is defined as the mode coefficient divided by the maximum mode coefficient of all modes. Any mode whose significance level is less thanSIGNIFis considered insignificant and is not contributed to the mode combinations. The higher theSIGNIFthreshold, the fewer the number of modes combined.SIGNIFdefaults to 0.001. IfSIGNIFis specified as 0.0, it is taken as 0.0. (This mode combination method is not valid for SPOPT, PSD.)LabelLabel identifying the combined mode solution output.
DISP
—
Displacement solution (default). Displacements, stresses, forces, etc., are available.
VELO
—
Velocity solution. Velocities, "stress velocities," "force velocities," etc., are available.
ACEL
—
Acceleration solution. Accelerations, "stress accelerations," "force accelerations," etc., are available.
TDTime duration for earthquake or shock spectrum.
TDdefaults to 10.ForceTypeLabel identifying the forces to be combined:
STATIC
—
Combine the modal static forces (default).
TOTAL
—
Combine the modal static plus inertial forces.
Notes
Modes whose effective damping ratio defined in Equation 14–42 exceeds or equals 1.0 are not combined.
This command is also valid for PREP7.