Seismic risk and possible maximum loss (PML) analysis of reinforced concrete structures - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 743

0.5%

Viaduct 1 (longitudinal)
Viaduct 1 (transverse)
Viaduct 2 (longitudinal)
Viaduct 2 (transverse)

0.4%

0.3%

0.2%

0.1%

0.0%

0 500 1000 1500 2000 2500 3000

Evaluated loss (*10 000 yen)

27.5 Seismic risk curves of railway viaducts.

Finally, seismic risk curves for two viaducts (in two directions) are com-
puted using Equation [27.3], and are shown in Fig. 27.5. Similar conclusions
can be obtained: the seismic loss for viaduct 1 in the transverse direction is
remarkably higher for rare situations than other cases; for instance, at the
annual probability of 0.002 (i.e. 500-year return period level), the loss for
the viaduct 1 in the transverse direction is approximately fi ve times greater
than other cases. This example demonstrates that the use of seismic risk
analysis can provide an effective means to compare the seismic risk at stake
for structures with different seismic designs, and can facilitate the decision-
making regarding the replacement of old-type viaducts to new-type via-
ducts (note: the benefi t for such decisions is quantitatively evaluated.)

27.3.2 Reinforced concrete piers of a highway bridge

The next case study deals with reinforced concrete piers of highway bridges
(Yoshikawa et al ., 2011). The focus of this investigation is to examine the
effect of structural properties on the seismic risk curves and seismic loss
quantities, such as PML. In total, six reinforced concrete piers are considered;
the yield and ultimate displacement capacities of the six piers are summarized
in Table 27.2. The six concrete piers have different seismic capacities, some
are below the required seismic load level, while others exceed such a load
level. The construction site is set to a location in Shinjuku-ward, Tokyo. In
the context of Specifi cations for Highway Bridges (Part 5), the design
acceleration spectrum is defi ned as three classes by the soil conditions: Class
I (rock or shallow deposits), Class II (diluvium or alluvium), and Class III