RSPEC

Bulk Data Entry Specifies directional combination method, modal combination method, excitation direction(s), response spectra and scale factors.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
RSPEC RID DCOMB MCOMB CLOSE          
  DTISPEC1 SCALE1 X11 X12 X13        
  DTISPEC2 SCALE2 X21 X22 X23        
  DTISPEC3 SCALE3 X31 X32 X33        

Example 1

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
RSPEC 35 ALG SRSS 1.0          
  7 1.3 0.5 0.5 -1.        

Example 2

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
RSPEC 35 SRSS CQC 0.0          
  7 1.3 0.5 0.5 -1.        
  4 2.0 -2 -0.0 -1.        
  2 17. 0.5 -2.5 -1.        

Definitions

Field Contents SI Unit Example
RID RSPEC identification number. Must be unique.

No default (Integer > 0)

  
DCOMB Method for directional combination.
ALG (Default)
Algebraic
SRSS
Square root of sum of squares.
  
MCOMB Method for modal combination.
ABS (Default)
Absolute sum.
SRSS
Square root of sum of squares.
CQC
Complete quadratic combination.
NRL
Navy Research Laboratory's SRSS
  
CLOSE Modal frequency closeness parameter.

Default = 1.0 (Real)

  
DTISPECi Response spectrum reference. A DTI,SPECSEL entry identification number.

No default (Integer > 0)

  
SCALEi Scale factor for excitation.

No default (Real <> 0.0)

  
Xij Components of a vector representing ground excitation i, j = 1..3  

Comments

  1. DTISPEC2/SCALE2/X21/X22/X23 and DTISPEC3/SCALE3/X31/X32/X33 are optional ground excitations for multi-directional excitation. The directions of excitation have to be orthogonal to each other and will be reported as error otherwise.
  2. Refer to Response Spectrum Analysis in the User Guide for more details.