Section 5
5-209
The ductility reduction factor Q’ is calculated according to
section 3.2.5.
Q’= Q if T ≥ T
a
Q’= 1 + (T/T
a
) (Q-1) if T < T
s
If not regular Q’ = Q’ x 0.8
If the period T
s
of the soil is known and the soil type II or III T
a
and T
b
will be modified according to section 3.3.2.
Lateral loads for each direction are calculated for:
T ≤ Tb – Eq. 4.5. Section 3.4.4.2
')(
)(
1
1
Q
a
hW
W
hW
P
n
N
n
n
N
n
n
nn
n
∑
∑
=
=
=
T > Tb – Eq. 4.6/7/8. Section 3.4.4.2
P
n
= W
n
a / Q (K
1
h
i
+K
2
hi²)
Being:
K
1
= q { 1 – r (1-q)} Σ W
i
/ Σ (W
i
/h
i
)
K
2
= 1.5 r q (1-q) Σ W
i
/ Σ (W
i
/h
i
²)
q = (Tb/T)
r