Seismic risk and possible maximum loss (PML) analysis of reinforced concrete structures - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 742

tudinal direction, respectively. The structural elements such as columns and
beams were modeled as a beam element with nonlinear components at
plastic hinge region. The foundation springs for the spread-footings and the
piles were appropriately modeled with lateral, vertical and rotational stiff-
ness calculated based on each design code. Figure 27.4 compares the seismic
loss functions of two viaducts along transverse and longitudinal seismic
excitations, expressed in terms of annual expected seismic loss. It is noted
that the seismic loss functions for viaduct 1 (old code) are greater than those
for viaduct 2 (new code); in particular, the difference is large for transverse
direction. The main reason for this is the low lateral capacity in the trans-
verse direction of the viaducts designed according to the old code. To evalu-
ate the seismic risk analysis results quantitatively, the annual expected
seismic losses for two viaducts are listed in Table 27.1. It is indicated that
the annual expected loss of viaduct 2 signifi cantly decreased to 19% in the
transverse direction and to 63% in the longitudinal direction as compared
to viaduct 1. The inspection of a scalar risk quantity greatly facilitates the
comparison.

0.035

0.030

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

0.025

0.020

0.015

0.010

0.005

0.000

0 200

Peak bedrock acceleration (gal)

400 600 800 1000

27.4 Seismic loss function of railway viaducts.

Table 27.1 Annual expected loss ED for two types of viaduct

Annual expected seismic loss (yen)

Type Transverse Longitudinal

1992 code: Viaduct 1 64 500 16 600

2004 code: Viaduct 2 12 100 10 400

Ratio of 2004 value to 1992 value 18.8% 62.7%