Direction definition

Click the Direction definition button in the dynamic analysis parameter dialog to define the direction of spectral/seismic excitation.

The Resolution of a force (seismic/spectral) into directions option generates three seismic cases differing in direction of excitation. The excitation direction (X,Y,Z) defined at the top of the dialog is appropriately resolved for the case, (X,0,0) (0,Y,0), (0,0,Z). The names of the newly created cases contain information indicating which direction the excitation is defined. Therefore, values defined in the X, Y, Z fields are components of the excitation vector. Select Use normalized values to scale component values so that the resultant vector is a unit vector.

For a seismic case calculated according to codes PS 92 and AFPS 90, the parameter determining the spectrum direction is automatically set.

Cases are generated as soon as the dialog for defining seismic/spectral analysis parameters is closed.

You can define the following combinations.

• quadratic

  

  Note: A combination may be a signed combination.
• according to PS 92 code, chapter 6.4

  Group 1 Group 2 Group 3

  where:

  S_x, S_y, S_z - are the results of the automatically created cases for directions X, Y, Z, calculated according to SRSS or CQC combinations, respectively. Combination type may be selected in the Combination selection field.