Structural vulnerability analysis of civil infrastructure facing seismic hazards - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 218

10

21

20

19

C: cluster
m: member
r: ground link

C7

9

18

17

7

8

16

C4

14

C6

10 12

11

13

15

6

C2

9 8

m1 r22 r23

7 5

4

5

C1 C3 C5

m19 m20 m21

4

3

1

6

3 2

m8 m9 m4 m5 m6 m2 m3 m4

m7

m10 m11

m12

r23

m15

2

m13 m14 m7 m8 m9 m6 m7 r24

r24

1

m16 m17 m18

r22

All members are uniform

8.7 Structure in Example 2 and the corresponding clustering
hierarchy.

Table 8.1 Failure scenarios for the structure in Example 2

Minimum
demand
scenario

Minimum
failure scenario

Maximum
failure
scenario

Specifi c failure
scenario (as an
example)

Introduce a pin
in any of the
members m4
(or m2 or m6)

Introduce a pin
in member
m19 or m20
or m21

Introduce a
pin either
in member
m2 or m6

Introduce a pin
in member
m10

Separateness
0.99 (for m4)

Separateness
0.2

Separateness
1.0

Separateness
0.8

Vulnerability
index 52.3

Vulnerability
index 7.5

Vulnerability
index 52.8

Vulnerability
index 30.2

minimum failure scenario. Notice that damage to any of these does reduce
the well-formedness of the structure, but the structure as a whole still stands.
Identifi cation of such degradation of structural quality is a useful aspect of
vulnerability analysis. The maximum failure scenario is obtained by intro-
ducing a pin either in m2 or m6. This causes total collapse of the structure
hence it is a total failure scenario. The intuitive and perhaps more obvious
candidate is m1. Certainly a pin in m1 will cause total collapse but as the