Effect of soil–structure interaction and spatial variability of ground motion on seismic risk assessment of bridges - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 600

22.2 Finite element models of the abutment-embankment system of
the TY3 overpass along the Egnatia Highway, Greece.
of abutment type, foundation-embankment-backfi ll geometry, and soil
properties. The idea was to derive relationships that can be potentially used
in cases where more accurate data are not available. Six typical RC Cali-
fornian bridges (namely Route 14, LADWP, W180, MGR, Adobe and La
Veta) and a Greek one (TY3 overpass along the Egnatia Highway) consist-
ing of box-girder superstructures, seat-type abutments and shallow pile
foundations were studied. Given the short spans and relatively high deck
stiffness of the particular structures, the embankment mobilization and the
inelastic behaviour of the soil material under high shear deformation levels
was found to have a signifi cant effect on the response of the bridge under
seismic loading. The geometry of the TY3 case studied is illustrated in Fig.
22.2, while indicative distribution of plastic strains in the 3D space are
depicted in Figs 22.3 and 22.4 for the transverse and longitudinal direction,
respectively. The relative stiffness of the embankment-abutment system of
all bridges examined is indicatively presented in Fig. 22.5 in the form of
pushover curves reaching an ultimate displacement of 10 cm, assumed to
be a limit value of abutment shear failure.
22.3.2 Dynamic mobilization of bridge embankments under
seismic excitation
Recent research studies (Goel and Chopra, 1997; Kotsoglou and Pantazo-
poulou, 2007, 2009; Makris and Zhang, 2004; Mwafy et al. , 2010) showed
that for fl exible abutment-pile foundation systems, conventional pushover
analysis studies may be insuffi cient. A notable reason is the nonlinear