ASCE Conference: The Technical Council
on Lifeline Earthquake Engineering (TCLEE 2003)
The Sixth U.S. Conference and Workshop on Lifeline Earthquake
Engineering in August 2003 Long Beach California.
Authors:
Bardia Emami (Senior Design Engineer, Optimum Engineering Solutions)
W. N. Marianos (Senior Associate, Modjeski and Masters Inc.)
Abstract
The Applied Technology Council (ATC), in a joint venture with
the Multidisciplinary Center for Earthquake Engineering Research
(MCEER), has recently developed Comprehensive Specifications for
the Seismic Design of Highway Bridges (National Cooperative Highway
Research Program, NCHRP Project 12-49). The American Association
of State Highway and Transportation Officials (AASHTO) is considering
these recommended specifications for possible incorporation into
the future AASHTO Load and Resistance Factor Design specifications.
The primary objective of the NCHRP Project 12-49 was to develop
seismic design provisions that reflect the latest research findings,
design philosophies, and design approaches. Henceforth, implementation
of the newly developed provisions will ensure enhanced seismic
performance of highway bridges.
In this study, the highway bridge seismic design procedures of
the current AASHTO and proposed NCHRP provisions are compared
for the substructure and superstructure of the bridge remain the
same for both provisions. An existing bridge located in a high
seismic zone of Missouri with Seismic Performance Category "D"
is redesigned according to the proposed NCHRP provisions. In this
project, this bridge has been redesigned using the NCHRP provisions
by Operational Performance Level for the Maximum Considered Earthquake
(MCE) with a 3% of probability of exceedance in 75 years (with
an approximate return period of 2500 years). By the new design
the bridge will remain functional after the MCE as a critical
bridge with lifeline performance.
This research indicates that changing from the current AASHTO
Standard to the new provisions requires 49% increase of reinforcing
steel for this bridge. Transverse reinforcement of the piles increases
significantly for the requirements of the new provisions (2500%
increase). By using the new provisions, concrete increases 72%
at wing-walls and the piles.
If you wish to have a complete copy of any of the articles, please
contact publications@openso.com.
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