Response Spectrum Wizard : UBC (1994)

The UBC 1994 spectrum is defined by a set of parameters defined in the code.

Zone Number

This is the Zone in which the structure is to be located and is one of 1, 2A, 2B, 3, 4 as defined in Table 23-I).

Soil Type

Enter S1, S2 or S3 for the soil type as described in Table 23-J. Type S4 soil requires specialist geotechnical advice.

Importance Factor

Determine the importance factor ($I$) from Table 23-L.

Structural System Factor

The structural system factor ($R_w$) is determined from Table 23-O (building structures) or 23-Q (non-building structures).

Empirical Building Period

Enter the value of the empirical building period derived from the code. (Clause 2334(b) 2A.)

Target Base Shear

Select from 90% or 100% as determined from Clause 2335(e)3.

Factor for Vertical Excitation

It is common to reduce the spectral values for vertical excitation to ⅔ of that used for horizontal excitation.

Ignore Short Period Force Reduction

It may be unconservative to reduce spectral values for low periods. This option ignores the reduction and extends the plateau to cover the low periods.