Civil Engineering Reference
In-Depth Information
0.40
0.35
0.30
0.25
0.25
0.20
0.20
0.15
0.15
0.04
0.10
0.10
0.02
0.05
0.05
0
0
0.02
0.04
0
0
0
0.05
0.1
Measured,
d
(a)
0.15
0.2
0
0.05
0.1
Measured,
d
(b)
0.15
0.2
26.3
Comparison between measured and predicted deformation
demands based on (a) deterministic and (b) probabilistic models.
Shear demand model
The probabilistic shear demand model is formulated as the natural loga-
rithm of the shear demand at the base of the tower normalized by the mean
value of the yield shear force, defi ned as
V
ˆ
y
ˆ
y
A
(3/4)(
R
2
r
2
)/(
R
2
=
+
+
Rr
+
r
2
), where
ˆ
y
=
expected yield stress of steel,
A
=
tower base cross-section
area, and
R
and
r
outer and inner diameter of the tower section, respec-
tively. The model selection results in the following probabilistic shear
demand model:
=
K
K
S
⎛
⎜
⎞
⎟
+
⎛
⎜
⎞
⎟
ˆ
ˆ
(
)
=
(
)
++
(
)
+
t
a
D
xw
,,
q
d
xw
,
θθ
d
xw
,
θ
ln
θ
ln
v
v
v
v
1
v
2
v
v
3
v
4
g
f
WT
H
⋅
PGV T
H
⋅
⎛
⎜
⎞
⎟
+
⎛
⎜
⎞
⎟
+
s
n
n
+
θ
ln
θ
ln
σ ε
v
5
v
6
v
v
H
H
[26.10]
As in developing the deformation demand model, due to the lack of prior
information, we use a non-informative prior in assessing the posterior sta-
tistics of the model parameters,
v
), which are presented in Table
26.5. Figure 26.4 shows a comparison between measured and predicted
shear demands. Comments analogous to those for the deformation demand
model (Fig. 26.3) can be made also for the shear demand model based on
Fig. 26.4.
Θ
v
=
(
θ
v
,
σ
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