Overall Conceptual Seismic Design and Local Seismic Capacity Design for Components of Bridges - Structural Seismic Design Optimization and Earthquake Engineering - page 302

From the perspective of overall linear concep-
tual seismic design for several typical bridges,
four design strategies are mainly introduced in the
chapter to make the structure's dynamic character-
istics adapt to the site conditions and let the seismic
demands become more uniform and rational along
structural components: optimal design for layout
and detail of continuous girder bridge, design of
towers for long span floating cable-stayed bridge,
seismic isolation mechanism of elastic cables in
cable-stayed bridge, and seismic potential and
performance for long span SCC bridges. For a
long span continuous girder bridge, the optimal
adjustments of the piers form and locations of
expansion joints are proposed to make the stiff-
ness distribution better suit to the site conditions.
For a long span cable-stayed bridge, a new-type
spatial bridge tower is proposed to replace the
original inverted Y shape tower based on elastic
response spectrum analyses. The influences of
the cable stiffness on the dynamic characteristics,
seismic displacement and forces are investigated
for another floating system cable-stayed bridge
installed with the elastic cables seismic isolation
device. For the new-type SCC bridge, the seismic
potential is further confirmed based on response
spectrum analyses of a four span continuous girder
bridge and a long span SCC arch bridge. Amounts
of numerical analyses and result comparisons
show that the proposed overall conceptual seismic
design strategies can decrease the seismic demands
and achieve a balance between the seismic force
and displacement, and thus improve the seismic
performance for bridges.
From the perspective of local nonlinear seismic
capacity design for components, three strategies,
innovation of cable sliding friction aseismic
bearing for bridges, bridge piers reinforced with
SFRC and pile group foundations strengthened
with SPPs are proposed to improve the seismic
capacities for components of bridges. Based on the
advantages of typical frictional isolation devices
and displacement restraining capabilities of cables,
a new cable sliding friction aseismic bearing is

invented and its seismic performance is studied by
the theoretical analysis and experimental testing.
The seismic capacities of bridge piers wholly and
locally reinforced with SFRC are studied based
on the presented nonlinear material constitutive
model of SFRC and the plastic hinge length and
the reasonable range locally reinforced with SFRC
are determined for the single-column bridge pier.
For pile group foundations reinforced with SPPs,
its seismic capacities, hysteretic performance
and energy dissipation capabilities are studied
by numerical simulations and low cycle loading
experiments. Theoretical analyses, experimental
studies and some effective comparisons show
that the presented local seismic design strategies
of components of bridges are economical, ap-
plicable and valid.

ACKNOWLEDGMENT

This research is supported by the Ministry of
Science and Technology of China (most recently
under Grant No. SLDRCE 09-B-08), the National
Natural Science Foundation of China (most recent-
ly under Grants No. 50978194 and No. 90915011),
and Kwang-Hua Foundation for College of Civil
Engineering at Tongji University. Such support is
gratefully acknowledged by the authors.

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