SUMMARY REPORT OF THE
NCHRP 20-68A – US Domestic Scan Program
Scan 11-02: Best Practices Regarding Performance of Accelerated
Bridge Construction (ABC) Connections in Bridges Subjected To MultiHazard and Extreme Events
Presented by:
Alexander K. Bardow, P.E.
State Bridge Engineer
Massachusetts Department of Transportation
SPECIAL NOTE:
The work described in this document was conducted as part of NCHRP Project
20-68A, the U.S. Domestic Scan program. This program was requested by
the American Association of State Highway and Transportation Officials
(AASHTO), with funding provided through the National Cooperative
Highway Research Program (NCHRP). The NCHRP is supported by
annual voluntary contributions from the state departments of transportation.
Additional support for selected scans is provided by the U.S. Federal
Highway Administration and other agencies.
This report IS NOT an official report of the National Cooperative Highway
Research Program, Transportation Research Board, National Research
Council, or The National Academies. This report was prepared by the scan
team for Scan 11-02 Best Practices Regarding Performance of
Accelerated Bridge Construction (ABC) Connections in Bridges
Subjected To Multi-Hazard and Extreme Events, whose members are
listed herein. Scan planning and logistics are managed by Arora and
Associates, P. C.; Harry Capers is the Principal Investigator. NCHRP
Project 20-68A is guided by a technical project panel and managed by
Andrew C. Lemer, Ph.D., NCHRP Senior Program Officer.
Scan Team Members
Scan Team Chair:
Jugesh Kapur, PE, SE,
Washington State DOT
Scan Team Members:
Alexander K. Bardow, PE, Mass DOT
Waseem Dekelbab PhD, PE, TRB
Michael Keever, Caltrans
M. Saiid Saiidi*, PhD, PE, University
of Nevada, Reno
Joshua Sletten, SE, Utah DOT
Dan Tobias, PhD, SE, Illinois DOT
W. Phillip Yen, PhD, PE, FHWA
*Subject Matter Expert preparing
reports and presentations
Objective

Identify connection details that are used
in the United States for ABC and which
have performed well under extreme
events, natural or man-made, such as
waves and tidal action or storm-surges,
seismic events, blast, and other large
forces.
Scan Team Events
Several conference calls prior, in
between, and subsequent to scans
 Desk Scan
 Organizational meeting: November 17,
2011

Desk Scan Objective
Further the efforts of the full scan team in
acquiring information of value to the
transportation community.
 Increase the cost-effectiveness of a full scan
by advising a team where best to commit its
time during travel
 Help to refine the scope of the scan by
identifying relevant sources of information
around the country and narrowing the focus
of the scan as needed.

Desk Scan Tasks

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Summary review of the most relevant reports,
papers, and web materials
Collect and organize amplifying questions from
scan team members
Extensive survey of nine states with one or
more extreme events and a known history of
activities and interest in ABC
Summarize desk scan findings in a report
Recommend list of states and institutions to be
visited or included in the scan through
conference calls
Organizational Meeting – Nov. 2011



Refined and finalized amplifying questions
Finalized list of states and institutions to be visited
or participate through conference calls
Week 1: March 25-31, 2012
Visit Massachusetts* and Florida DOTs;
Web conference participation by University of Buffalo and Texas
and S. Carolina DOTs

Week 2: April 22-28, 2012
Visit Utah, Washington*, and Nevada DOTs;
Caltrans engineers/researchers participation while team meets in
Nevada
Visit University of Washington, Seattle, and University of
Nevada, Reno, laboratories
* Several bridge site visits in Massachusetts and Washington
Scan Meeting Participants


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DOT Management
Officials
Engineers
Contractors
Fabricators
Suppliers
Researchers at
selected institutions
studying ABC
connections under
extreme events
Summary of Amplifying Questions
General Issues on Design for Multi-Hazard
Loading
 ABC Design for Multi-Hazard Loading
 Decision and Design Tools for ABC Use
 Past ABC Application
 Partnership with Industry and Research
Institutions
 ABC Inspection and Maintenance

Summary of Initial Findings
8 Topic Areas:
1. Extreme load consideration for bridges and
2.
3.
4.
5.
6.
7.
8.
ABC connections
ABC connection details
ABC connection maintenance
Standardization of ABC connection details
and processes
ABC connection research
Innovative ABC connections
Monitoring ABC connections and
prefabricated bridge elements and systems
Other findings
1 - Extreme Load Consideration
for Bridges and ABC Connections
MH load combination considered only to a
limited extent even in conventional bridges due
to limited guidance and because of low
probability of simultaneous occurrence
 No information specific to ABC connection
design under MH loading
 Despite maturity of seismic design of
conventional bridges, no AASHTO seismic
design guidelines for ABC.
 Current AASHTO Guide restriction on splicing in
SDC C and D– major hurdle on ABC use in high
seismic zones

1 - Extreme Load Consideration for
Bridges and ABC Connections (Cont’d)
FHWA funded study to develop MH design
guidelines for bridges in progress at U. of Buffalo
- not specific to ABC.
 AASHTO LRFD framework is used as a platform
to develop MH LRFD
 Examples of current MH load combination used
in practice:

 Combined seismic and scour loads
 Wave action, wind, anchorage breakage, and vessel
collision for floating bridge

Advanced materials should allow for higher
performance levels than conventional bridges
under MH loading
2 - ABC Connection Details
Many ABC connection types have been and
continue to be developed
 Several states use FHWA-HIF-12-013 (Nov.
2011): Accelerated Bridge Construction Experience in Design, Fabrication and
Erection of Prefabricated Bridge Elements
and Systems.

2 - ABC Connection Details (Cont’d)

Superstructure connection examples:
 Unrestrained joints under lateral loads
 Unrestrained joints under uplift due to storm
surge
 Various concrete or grout mixes for closure pours
for partial or full depth precast decks
 CIP concrete at closure pours between precast
girders and at abutments.
 Continuous superstructure/approach slabs in
SPMT moves or slides
2 - ABC Connection Details (Cont’d)

Substructure connection
examples :
I.
Precast column
embedded into drilled
shaft, footing, or cap
beam
2 - ABC Connection Details (Cont’d)

Substructure connection examples (Cont’d) :
II.
Grouted couplers embedded in precast column
or in pile shaft, footing, or cap beam
2 - ABC Connection Details (Cont’d)

Substructure connection examples (Cont’d) :
III. Precast columns with extended bars inserted in
grouted metal sleeves
3- ABC Connection Maintenance
Insufficient history to make a call (if
maintenance issues are different for ABC
connections)
 General perception: should not be different if
ABC connections are emulative (verified by a
few ABC projects built in the 1990’s)
 In one state ABC projects are inspected
annually to address any issues and develop
performance data base

3 - ABC Connection Maintenance (Cont’d)
Precautionary measures to avoid
maintenance problems, e.g. “greased and
sheathed” tendons, plastic ducts, posttensioning of deck panels, etc.
 Importance of grout quality, application, and
consolidation is recognized.
 Deck slabs post tensioned together
 States are aware of the need for inspection
and maintenance manuals when using
unconventional materials and details.

4 - Standardization of ABC Connection
Details and Processes

Standard ABC connections:
 There is a strong push from stakeholders to
standardize ABC connections
 Philosophical differences: well-defined details vs.
versatile details

Standard decision making process for
selecting ABC over conventional construction
 Consistent application of user costs
4 - Standardization of ABC Connection
Details and Processes (Cont’d)

Examples of manuals for standard
details:
 PCI – Northeast
 Several states utilizing FHWA 2011 ABC
report
 Manuals for each precast element type
 Manuals for SPMT moves
 List of preapproved grouted couplers
4 - Standardization of ABC Connection
Details and Processes (Cont’d)
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Standard decision making process for
selecting ABC over conventional construction
National effort: Oregon study
Many states have or are developing their own
process
User costs are generally included and can
help justify ABC
Initial ABC cost may be higher because of
financial risk to contractors; could become
lower over time because of saving in durationdependent costs
5 - ABC Connection Research
On-going studies on high-early strength
concrete for closure pours
 Other ABC connection research focused on
seismic performance
 Seismic studies may serve as a guide for
other extreme load studies
 Two categories of seismic ABC connection
research: emulative and non-emulative

5 - ABC Connection Research (Cont’d)

Successful emulative ABC connections
 Precast columns embedded into footings, piles, or
cap beams
 Large diameter column bars embedded in
corrugated metal ducts
 Various standard couplers
 Various methods to convert multi-girder pier cap
connections to integral pier caps

Research continues
5 - ABC Connection Research (Cont’d)

Successful non-emulative ABC connections
 Motivated by versatility of precast members
 Performance level exceeds conventional construction
 Post-tensioned segmental columns
5 - ABC Connection Research (Cont’d)


Successful non-emulative ABC connections (Cont’d)
 Energy dissipation with advanced materials and
details: e.g. shape memory alloys, HPC, built-in
rubber, FRP wrapping, and concrete-filled steel and
FRP tubes
Research continues
FRP Wrap
Conc.-Filled FRP Tube
Built-in Rubber
6 - Innovative ABC Connections
ABC is innovation in CONSTRUCTION
 Other innovation possible through ABC
 Innovative precast double-T precast girders
 Folded plate girders
 Concrete-filled tube arches
 Post-tensioned bridge decks, abutments, cap
beams
 Base isolation to simplify ABC connections
 FHWA-HFL good mechanism to bring
innovation to practice

7- Monitoring ABC Connections and
Prefabricated Bridge Elements
Done on a selected basis for nonemulative connections
 May not be necessary for emulative
ABC connections
 Short-term monitoring common in SPMT
moves
 Frequent (annual, in addition to NBIS
biennial) inspection of ABC bridges

8 - Other Findings
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High enthusiasm and interest in ABC
Key to success in ABC: COMMUNICATION
among top management, designers,
contractors, fabricators, industry and public
Early involvement of contractors and fabricators
in design and planning - design-build projects
provide such an opportunity
Site casting has to be used when precast plants
are remote
Shift of role: from CONSTRUCTION to
INSTALLATION - contractors need to be open
8 - Other Findings (Cont’d)
Education and training needed for ABC
connection design and inspection
 ABC design manuals are being integrated into
state bridge design manuals
 Documenting ABC lessons is essential.
Examples:

 Convert circular columns to octagonal shape to cast
on the side
 Avoid multi-segment columns unless necessary
 Transport issues of short heavy segment (load has to
be spread over many axles)
Recommendations
Continue research into MH load combinations
and ABC connections. Initiate NCHRP project to
synthesize this research, fill knowledge gaps
and develop design procedures for AASHTO
LRFD.
 Establish a full time national center on ABC
under MH as a central resource for collecting
on-going research, detailing, construction and
ABC performance both long term and after MH
 Build on FHWA Everyday Counts vision to reach
out to AGC, decision makers, and others to
promote ABC

Recommendations (Cont’d)
Expand demonstration ABC projects through the
FHWA IBRD program in areas with extreme
event loads
 Continue research on emulative ABC
connections to facilitate ABC use in areas of
high seismicity and other extreme events
 Continue and expand research on ABC
connections with advanced materials and
details under MH loading
 Collect and interpret field data of ABC
connection performance. Explore integration of
effort with FHWA LTBP

Implementation Actions
Seminars and webinars at venues attended by bridge
engineers, contractors, suppliers, fabricators, etc.,
such as AASHTO SCOBS, TRB Annual Meeting and
TRB conferences, and websites (FHWA, NCHRP 2068, Florida IU ABC site)
 Identify champions in relevant AASHTO Technical
Committees and follow up on implementation of
recommendations
 Form an ABC user group to bring together various
stakeholders
 Express support for current FHWA MH loading studies
to FHWA management

Implementation Actions (Cont’d)

Problem statement to develop Performance
Based Design guidelines of emulative and
non-emulative ABC connections
Garner support for a national center on ABC
under MH loading
 Technical articles summarizing the scan findings
for publication in the TRB TR News and other
industry journals
 Coordinate with FHWA and others to help
implement the scan recommendations
