Analysis and modelling of the seismic behaviour of high ... - Ingegneria

4. SEISMIC RESPONSE OF PARTIAL-STRENGTH COMPOSITE JOINTS
iv. Determination of the target displacement for the equivalent SDOF system with
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period T* and unlimited elastic behaviour, given by:
d
*
et
=
*
T
2π
2
S
e
( 4.34 )
where Se(T * ) is the elastic acceleration response spectrum at the period T * . For
the determination of the target displacement d * for structures in the short-period
range and for structures in the medium and long-period ranges different
expressions should be used as indicated below. The corner period between
the short- and medium period range is TC.
T T <
*
If C
:
*
* d et
T
d t
≥
q
T
u
C *
( q −1)
d
1 + u * et
= ( 4.35 )
where qu is the ratio between the acceleration demands in the structure with
unlimited elastic behaviour Se and in the structure with limited strength.
* *
If y
e
S m
q = ( 4.36 )
u
F m ≥ S
*
e
*
Fy
, the response is elastic and
d = d .
v. Determination of the target displacement for MDOF system, given by:
*
t t
d = Γ d
( 4.37 )
The target displacement corresponds to the control node. Moreover, the
relation between different quantities can be visualized in Figure 4.48 and in
Figure 4.49). The figures are plotted in acceleration - displacement format. The
period T * is represented by the radial line from the origin of the coordinate
system to the point at the elastic response spectrum defined by coordinates
d * =(T * /2π) 2 ⋅Se and Se.
*
t
*
et