Geoscience Reference
In-Depth Information
1
1
R
e
= 0-10 km
R
e
= 10-20 km
0.8
0.8
PGA
AI
PGV
0.6
0.6
0.4
0.4
0.2
0.2
0
0
0.1
1
10
0.1
1
10
1
1
R
e
= 20-30 km
R
e
= 30-40 km
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
0
PERIOD (sec)
PERIOD (sec)
0.1
1
10
0.1
1
10
Fig. 4.2. Average elastic response spectra fordifferent distance
increments and scaling scheme
2.2. SIMULATED ACCELERATION RECORD
The second option is to use simulated acceleration time histories generated compatible
with the estimated earthquake hazard spectra. The hazard spectrum compatible accelera-
tion time histories generated for each cell based on the procedure suggested by Deodatis
(1996) and Papageorgiou et al. (2000) were utilised for conducting site response analy-
ses. Three simulated acceleration time histories were used for each cell for site response
analyses.Theaverageofthecalculatedaccelerationresponsespectrawasusedformicro-
zonation with respect to ground shaking intensity and for fitting the best NEHRP enve-
lope spectra to calculate the spectral acceleration to be used in assessing the building
stock vulnerability.
Themicrozonationmapswithrespecttospectralaccelerationsatshortperiodrangeusing
one set of simulated (Kılıc¸ et al., 2006) and two different sets of real acceleration time
histories are shown in Figure 4.3. Even though there is a general agreement among all
three options, there are also important differences. In this case, it would be difficult to
justify the selection of one option to estimate the building stock vulnerability. As can
be observed, using simulated acceleration time histories generally yielded higher ampli-
tudesindicatingmoreconservativesolution.However,thedegreeofconservatismcannot
be identified and the generated acceleration records may be considered unrealistically
demanding as shown in Figure 4.4. Thus at this stage the use of regional earthquake
hazard compatible previously recorded and PGA scaled real acceleration records appear
more suitablefor microzonation studies.
