Civil Engineering Reference
In-Depth Information
(2) Modal decomposition
Now consider the structure is excited by the El Centro north-south ground acceleration rec-
ord from the 1940 Imperial Valley Earthquake, the peak ground acceleration of which equals
0.2 g. By using the modal decomposition method in Section 8.2, the displacement, velocity and
acceleration responses of the first three models are shown in Figures 8.19.
(3) Responses summation
Base and top floor displacement and acceleration of the structure are computed by the modal
superposition method and the state space method, and are plotted together in Figure 8.20. First,
(a)
(b)
1500
1500
m
41
(
t
)
m
37
(
t
)
1000
1000
500
500
0
0
-500
-500
-1000
-1000
-1500
-1500
0
10
20
30
0
10
20
30
Time (s)
Time (s)
(c)
(d)
1500
1500
m
37
(
t
)
m
41
(
t
)
1000
1000
500
500
0
0
-500
-500
-1000
-1000
-1500
-1500
-0.0015
-0.0005
0.0005
0.0015
-0.0024 -0.0012
0
0.0012
0.0024
Plastic rotation (rad)
Plastic rotation (rad)
Figure 8.21
Global responses of the frame: (a) moment response at PHL #37; (b) moment response at
PHL #41; (c) moment and plastic rotation relation of PH #37; (d) moment and plastic rotation relation
of PH #41.
