Environmental Engineering Reference
In-Depth Information
u
F
, P
F
Displacement and harmonic loading of foundation
G
S
, q
S
, t
S
Shear modulus, density, and Poisson's ratio of soil
r
F
Equivalent radius of foundation
h
u
;
h
uz
Rocking and torsional mass moments of inertia of foundation
K
x
, K
y
, K
z
, K
uz
Stiffness coefficients of foundation-soil system
C
x
, C
y
, C
z
, C
uz
Damping coefficients of foundation-soil system
f
D
Natural frequency of tuned mass damper/tuned liquid column
damper
l
Mass ratio between tuned mass damper and modal mass of
structure
f
H
Natural frequency of structure
f
D,opt
, D
D,opt
Optimal frequency and damping ratio of tuned mass damper/
tuned liquid column damper
u
;
u
;
u
Displacement,
velocity,
and
acceleration
of
liquid
column
motion of tuned liquid column mass damper
d
P
Pressure loss
x
D
Fundamental circular frequency of tuned mass damper/tuned
liquid column damper
c
1
;
c
2
1. and 2. geometric factor of tuned liquid column damper
x
þ
x
g
;
x
þ
x
g
Acceleration and displacement of structure
caused by base
excitation
L
1
, L
2
1. and 2. effective length of liquid column
a
Angle of the liquid column
V, H
Vertical and horizontal length of the liquid column
A
V
, A
H
Area of the vertical and horizontal liquid column
D
H
;
x
H
Damping ratio and fundamental circular frequency of structure
l
Mass ratio between tuned liquid column damper and modal
mass of structure
f(t)
Dynamic excitation force
k
act
, c
act
Stiffness and damping coefficient of seismic actuator
m
tf
Total mass of turbine and foundation
X
act
Frequency of seismic actuator
f
g
(t)
Seismic excitation force
x
g
;
0
;
x
g
;
0
Realized seismic foundation motions
x
g
;
seis
;
x
g
;
seis
Desired seismic foundation motions
12.1 Introduction
Wind turbines count as one of the most important techniques of renewable energy
production and perform an increasing share in the electric power market.
According to the statistics presented in the annual report of Global Wind Energy
