Assessing seismic risks for new and existing buildings using performance-based earthquake engineering (PBEE) methodology - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 307

nonstructural components whose performance is sensitive to fl oor accelera-
tion and another performance group might be sensitive to the inter-story
drift between the second and third fl oor. The selection of components in
each performance group is based on engineering judgment of the impor-
tance of the contribution of these components to the overall performance
of the structure.
A suffi cient number of damage states (DS) are defi ned for each perfor-
mance group to completely describe a range of damage extents to the
components in the performance group. The damage states are defi ned in
relation to the repair actions needed. For each damage state, a damage
model (fragility relation) is used to defi ne the probability the component
will be equal or greater than the damage state given an EDP value.
Figure 12.2 shows an example of fragility curves defi ned for a performance
group.
As shown in Fig. 12.2 the performance group has four damage states. DS1
represents no damage, DS2 represent slight damage, DS3 represents severe
but repairable damage, and DS4 represents total replacement. Depending
on the demand expressed using the EDP value, the probabilities of the
performance group being in each damage state can be identifi ed from the
fragility curves. For example, if the EDP equals 1.5 g , the probability of
the components in the performance group being in DS1 is close to zero,
DS2 is approximately 0.5, DS3 is approximately 0.42, and DS4 is approxi-
mately 0.08.

1
0.9
0.8
0.7

DS2
DS3
DS4

0.6
0.5
0.4
0.3

0.2
0.1
0 0

1 2 3

EDP - peak floor acceleration [ g ]

4 5 6

12.2 Example of fragility curves.