Seismic analysis in AxisVM10 can be performed according to two different methods.

• Response Spectrum Analysis Method

• Analysis from acceleration diagram

seismic analysis with Response Spectrum Analysis Method

Calculate the first n vibration mode shapes and frequencies.

AxisVM generates equivalent static loads (for each vibration mode shape) which are then applied to the model in a static analysis. internal force results obtained for each mode shape are summed using the method described in design code specifications.

Supported Design Codes

• Eurocode 8 Code (EN 1998-1:2004)  
• German Code (DIN 4149:2005-04)
• Hungarian Code (MI-04.133-81)
• Italian Code (OPCM 3274)
• Romanian Code (P 100-92)
• Swiss Code (EN 1998-1:2004)

Defining parameters

• After creating a seismic load case additional load cases are calculated to represent seismic forces in X and Y direction (and in Z direction if a vertical spectrum is defined) with + and – signs. Two additional load cases represent the sum of the + and – effects.

• Design spectrum and other parameters required by the design code can be specified in a separate dialog. 
• Common parameters are:
  • Horizontal design spectrum
  • Vertical design spectrum
  • Design ground acceleration
  • Horizontal behaviour factor
  • Consideration of torsional effects
  • Combination method of modal responses

  • Combination method of spatial components

Results

Results of seismic load cases can be evaluated the same way as those of regular load cases. A seismic load group appears automatically so seismic loads contribute to the critical combination as well.

seismic analysis on the basis of acceleration diagram

Acceleration functions can also be used for seismic analysis. In this case it is recommended to obtain proper seismic accelerograms and assign these functions to support nodes to analyse the effects of the earthquake. This method provides more exact results than the response spectrum analysis and can be used even if nonlinear elements are defined in the model (nonlinear supports, tension-only trusses, etc.). Its disadvantage is that it cannot be combined with other load types automatically.