Page 2 - KS_materijal za vezbe_2015

Introduction to the RC building example. Modeling and analysis of the design example.
P. Fajfar and M. Kreslin

Figure 2.1.2 Schematic cross-section of the building

2.1.2 ACTIONS

2.1.2.1 Seismic actions

The seismic action is represented by the elastic response spectrum, Type 1 (M s > 5.5, EN 1998-
1/3.2.2.2(2)P) for soil B (EN 1998-1/Table 3.1). The reference peak ground acceleration amounts to
a gR = 0.25g. The values of the periods (T B , T C , T D ) and of the soil factor (S), which describe the shape
of the elastic response spectrum, amount to T B = 0.15s, T C = 0.5 s, T D = 2.0 s and S = 1.2 (EN 1998-
1/Table 3.2). The building is classified as importance class II (EN 1998-1/Table 4.3) and the
corresponding importance factor amounts to J I = 1.0 (EN 1998-1/4.2.5(5)P). Therefore the peak
ground acceleration is equal to the reference peak ground acceleration a g = J I *a gR = 0.25g. Using the
equation in EN 1998-1/3.2.2.2 the elastic response spectrum was defined for 5% damping.
For the design of the building the design response spectrum is used (i.e. elastic response spectrum
reduced by the behaviour factor q). Determination of the behaviour factor q, which depends on the
type of the structural system, regularity in elevation and plan, and ductility class, is described in
Section 2.4. It amounts to 3.0. The design spectrum for elastic analysis was defined using
expressions in EN 1998-1/3.2.2.5(4)P. The elastic response spectrum and the design response
spectrum (q = 3.0) are plotted in Figure 2.1.3.

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