Design and Construction of Modern Curved Bridges
by
James S. Davidson, Ramy S. Abdalla
and Mahendra Madhavan
Department of Civil and Environmental
Engineering
The
Prepared by
UTCA
The
and the
UTCA Report Number 01223
Technical Report Documentation Page
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1. Report No FHWA/CA/OR- |
2. Government
Accession No. |
3. Recipient
Catalog No. |
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4. Title and
Subtitle Design and
Construction of Modern Curved Bridges |
5. Report Date |
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6. Performing Organization Code |
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7. Authors James S.
Davidson, Ramy S. Abdalla, and Mahendra Madhavan |
8. Performing
Organization Report No. UTCA Report 01223 |
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9. Performing
Organization Name and Address Department of Civil & Environmental Engineering The |
10. Work Unit No. |
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11. Contract or Grant No. DTR598-G-0028 |
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12. Sponsoring Agency Name and Address The |
13. Type of Report and Period Covered Final Report; |
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14. Sponsoring Agency Code |
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15. Supplementary Notes |
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16. Abstract The overall objectives of
this project were to investigate and synthesize state-of-the-art practice for
the efficient design and construction of curved bridges, and to identify
research needs regarding strength and stability of curved bridges. The project resulted in progress towards
establishing a curved steel bridge stability research program within The
University of Alabama system. The work
was conducted by graduate students whose efforts have resulted in several papers
and presentations. The project enabled the investigators to participate in national
level conferences and meetings. Research
literature was collected that will facilitate continued research
efforts. The planning, design,
fabrication, and construction of a local curved I-girder bridge flyover was
studied to gain a better understanding of practical challenges associated
with curved bridge design and construction.
Curved I-girder and box girder stability topics that can be tackled
within a university research environment were identified through the
background research and interaction with industry leaders. A meeting with Alabama Department of Transportation
bridge engineers provided insight into the research and education needs and
interests of The generation of so much
information on this topic and contacts with so many experts in the field made
the Principal Investigator uniquely prepared to advance the state of practice
of curved bridge design in |
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17. Key Words Bridges, curved bridge, I-girder, box
girder, stability, specifications |
18. Distribution
Statement |
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19. Security Classif (of this report) Unclassified |
20. Security Classif. (of this page) |
21. No of Pages |
22. Price |
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Form DOT F 1700.7 (8-72)
Contents
Contents............................................................................................................................... iii
Figures.................................................................................................................................. iv
Executive Summary................................................................................................................ v
1.1
General 1
1.2 Objectives..................................................................................................... 2
1.3 Scope and Project Description....................................................................... 3
1.3.1 Tasks................................................................................................ 3
1.3.2 Project Team..................................................................................... 4
1.4 Report Content and Organization................................................................... 5
2.1 Overview...................................................................................................... 6
2.2 Stability Research Accomplishments............................................................... 6
2.2.1
Design and
Construction of Curved Box Girder Bridges .................... 6
2.2.2
Stability of Curved I-Girders
during Construction .............................. 8
2.2.3 Analysis of
Single I-girders during Erection......................................... 8
2.2.4 Case Study of
the I-459 Flyover...................................................... 10
2.2.5 Papers,
Presentations, and Reports.................................................. 11
2.3 Outreach and Interaction.............................................................................. 12
2.3.1 Conferences
and Meetings............................................................... 12
2.3.2
Curved Bridge Research
Interests of the Alabama Department
of Transportation............................................................................. 13
2.4 Stability Research Topics............................................................................. 14
List of Figures
Number Page
2-1 Cross sections commonly used in curved bridge superstructures.................................. 7
2-2 Support conditions considered in lifting studies............................................................ 9
2-3 Construction site of the Galleria Flyover................................................................... 10
2-4 Erection of girders at the Galleria Flyover construction site........................................ 11
As the population of
The overall objectives of this
project were to investigate and synthesize state-of-the-art practice for the
efficient design and construction of curved bridges, and to identify research
needs regarding strength and stability of curved bridges. The project resulted in progress towards
establishing a curved steel bridge stability research program within The
University of Alabama system. The work
was conducted by graduate students whose efforts have resulted in several
papers and presentations. The project enabled the investigators to participate
in national level conferences and meetings.
Research literature was collected that will facilitate continued
research efforts. The planning, design,
fabrication, and construction of a local curved I-girder bridge flyover was studied
to gain a better understanding of practical challenges associated with curved
bridge design and construction. Curved
I-girder and box girder stability topics that can be tackled within a
university research environment were identified through the background research
and interaction with industry leaders. A
meeting with Alabama Department of Transportation bridge engineers provided
insight into the research and education needs and interests of
1.1 General
As
the population of
In
the early days of curved bridge design and construction, bridge superstructures
supporting curved roadway alignment were comprised of short straight girders
linked together at the supports. This
resulted in inefficient use of very short spans between support piers. As the technology for designing and fabricating
curved girders became available, it became possible to design curved bridges
with much greater distances between supports.
Today,
curved girders are widely used in bridge superstructures. The designer has many choices including
material (concrete vs. steel), cross-section shape (tub girder vs. I-beam),
etc. Furthermore, the past three decades
have resulted in advances in optimizing curved bridge design, resulting in
innovative, aesthetically pleasing structures.
However, due to the simple addition of curvature, the design and
construction of bridges becomes immensely more complicated than that of
straight bridges. While the girders,
stringers, and floor beams of straight bridges can be designed by systematically
isolating each member and applying standard loads, curved bridges must be
designed with careful consideration to system-wide behavior. In essence, the addition of curvature adds
torsion to the system that results in significant warping and distortional
stresses within the member cross-sections.
Furthermore, “secondary members” such as cross frames and diaphragms
that provide stability in straight bridges become primary load carrying members
in curved bridges.
Although
the design of curved bridges is much more complex than that of straight
bridges, there are no requirements specific to the design of curved bridges
integrated into the American Association of State Highway Transportation
Officials (AASHTO) Standard Specifications for Highway Bridges (AASHTO 1992). There is, however, the “Guide Specifications
for Horizontally Curved Highway Bridges,” which was first adopted in 1981
(AASHTO 1993). This “guide” is widely
recognized to be outdated, disjointed, and difficult to use. Several significant research projects have
been conducted over the past few years including the Federal Highway
Administration (FHWA) “Curved Steel Bridge Research Project (CSBRP)” and the
National Cooperative Highway Research Program (NCHRP) Project 12-38, “Improved
Design Specifications for Horizontally Curved Steel Girder Highway
Bridges.” Currently, NCHRP Project
12-52, “LRFD Specifications for Horizontally Curved Steel Girder Highway
Bridges,” is being conducted by Modjeski & Masters to prepare
specifications for the design and construction of horizontally curved steel
girder bridges (for both I- and box girders) in a calibrated load and
resistance factor design (LRFD) format that can be recommended to AASHTO for
adoption (www.modjeski.com).
Furthermore, many states have recently conducted or supported research
on curved bridge design and construction.
The only other bridge design document in the world that specifically
addresses curved bridge design is the Japanese “Guidelines for the Design of
Horizontally Curved Girder Bridges” by the Hanshin Expressway Public
Corporation (Hanshin 1988). Several
researchers, including the primary author of this report (Davidson), have demonstrated
disparity in the strength formulations between the Japanese and American curved
bridge design guides, which further emphasizes the need for additional
research.
In
addition to improving design equations for curved bridges, another area that
has been widely recognized for further research is that of lifting and
transporting curved girders during construction. By far, the most frequent problems are
encountered during construction. The
problems are typically more severe and more common than those encountered
during the construction of straight bridges.
During the construction of straight bridges, girders and stringers are easily
erected by one crane using one or two pick-up points, or by two cranes using
one pick-up point each. The individual
straight girders can simply be set in place with little concern for
instability. Lifting and setting
presents little difficulty for straight beams where the center of gravity is
coincident with the centroidal axis of the beam cross-section. But for horizontally curved girders, the
center of gravity is non-coincident with the cross-section centroid. Depending
on the lifting/support mechanism used, significant torsional stresses and
minor-axis bending stresses may be induced.
The handling and erection of horizontally curved girders requires
engineering expertise beyond that needed for the construction of straight
bridges. Engineers not experienced in
the design of curved bridge systems often make the mistake of assuming that
behavior and design is the same as that for straight bridges. Instability during construction can easily
translate into unsafe conditions for construction workers, not to mention
unforeseen additional costs.
Because
of the increasing demand for curved bridges combined with challenges of design
and construction, there is need to investigate and synthesize state-of-the-art
practice for the efficient design and construction of curved bridges. This report summarizes the activities and
accomplishments of a first phase project aimed at establishing a curved steel
bridge research program within The University of Alabama system. A follow-on project, UTCA Project 03228, “Stability
of Curved Bridges during Construction,” is currently underway using the
contacts, literature survey, and research needs synthesis of this project. Technical results of the effort will be
disseminated through conference presentations and proceedings, journal
publications, student theses and dissertations, and the final report of UTCA
Project 03228.
1.2 Objectives
The
overall objectives of this project were to investigate and synthesize
state-of-the-art practice for the efficient design and construction of curved
bridges and to identify research needs regarding strength and stability of
curved bridges. Additional goals of the
project included:
·
Develop relationships with
Alabama Department of Transportation (ALDOT) bridge engineers, FHWA program managers,
prominent curved bridge researchers, and industry leaders;
·
Identify research needs and
topics suitable for graduate research;
·
Identify technology transfer
and continuing education needs of ALDOT and the bridge design industry of the
region;
·
Contribute to bridge
stability research needs through graduate student research;
·
Identify potential sources of
future support;
·
Transfer project results to
stakeholders.
1.3 Scope and Project Description
1.3.1 Tasks
The
four tasks of the project work plan and a synopsis of the accomplishments
associated with each are described below.
The work was accomplished over a 16-month period beginning
TASK 1. Synthesis of current practice
The
data-gathering effort involved investigating the current state-of-the-art
curved bridge design and construction practice around the country. The usual avenues of collecting information
such as publication database searches and Web-based searches were used. However, the synthesis largely depended upon
direct contacts by the investigators.
Many states have conducted investigations to improve the design and
construction of curved bridges and the resulting reports of such projects often
do not show up in the typical library or journal database search. Investigators at the