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Response spectrum generator according to UBC (U.S. standard, obsolete)

Procedure to input a new UBC 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 UBC - U.S. 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 UBC by selecting UBC - U.S. standard as Input type.

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.

Input type

Per code: the parameters Ca and Cv are calculated according to the selected seismic zone and soil profile type

User defined: the parameters Ca and Cv are defined manually by the user

Seismic zone

Seismic hazard zone (1, 2A, 2B, 3, 4)

Soil profile type

Soil profile type (SA, SB, SC, SD, SE, SF)

For soil profile SF, C_a and C_v are always defined by the user

Coefficient Na

Correction coefficient for C_a, only in the case of seismic zone 4 (=1.0 otherwise)

Coefficient Nv

Correction coefficient for C_v, only in the case of seismic zone 4 (=1.0 otherwise)

Ca

Spectral acceleration coefficient for short periods

Cv

Spectral acceleration coefficient for long periods

Theoretical background

For seismic zone 4:

g is the acceleration of gravity

Values of Ca and Cv

* For soil profile SF, the values of C_a and C_v are defined by the user.

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