Response spectrum generator according to Italian standard

Procedure to input a new Italian standard seismic spectrum

  1. Expand branch Libraries of the main tree menu.
  2. Expand sub-branch Loads.
  3. Start function Seismic spectrum to open the Seismic Spectrum Manager.
  4. Click button New.
  5. In combo box Input type select option Italian standard.
  6. Review and, if required, adjust the spectrum parameters.
  7. Click button Code parameter to review or modify the code-defined parameters of the spectrum.
  8. Confirm the code parameters with OK.
  9. Click OK to confirm the spectrum.
  10. Close the Seismic Spectrum Manager.

Spectrum definition and code parameters

A response spectrum can be defined according to Italian standard by selecting Italian standard as Input type.

update picture TO DO

Max frequency & Step

The values of the spectrum are generated between a maximum period of 4 seconds (=0.25 Hz) and the input maximum frequency, using the input Step value.

Code parameters

This button opens the dialogue defining the code-dependent parameters.

coeff. accel. ag

Value of the design acceleration expressed as a multiple of the acceleration of gravity g

ag - design acceleration

Design ground acceleration on type A ground

q - behaviour coefficient

Behaviour factor

S, Tb, Tc, Td manually?

When this setting is No, the values S, Tb, Tc, Td are obtained from table, depending on the subsoil type and direction of the seismic action

When this setting is Yes, the values S, Tb, Tc, Td are input manually

Direction

Direction of the seismic action, horizontal or vertical

Subsoil type

Ground type (A, B, C, D, E)

S - soil factor

Soil factor, obtained from table, depending on the subsoil type and direction

Tb

Lower limit of the period of the constant spectral acceleration branch, obtained from table depending on the subsoil type and direction of the seismic action

Tc

Upper limit of the period of the constant spectral acceleration branch, obtained from table depending on the subsoil type and direction of the seismic action

Td

Value defining the beginning of the constant displacement response range of the spectrum, obtained from table depending on the subsoil type and direction of the seismic action

Theoretical background

Horizontal design spectrum

Vertical design spectrum

Tabulated values

Direction Subsoil S [-] TB [s] TC [s] TD [s]
Horizontal A 1.00 0.15

0.4

 2.0
B 1.25 0.15 0.5 2.0
C 1.25 0.15 0.5 2.0
D 1.35 0.20 0.8 2.0
E 1.25 0.15 0.5 2.0
Vertical all 1.00 0.05 0.15 1.0