Development of UHPC Connection of Precast Bridge Elements (PBES) for Accelerate Bridge Construction Projects.
State DOTs operate under
great expectations to minimize impact to the traveling public and commerce that
result from construction activities.
Given the operational needs of DOTs, project timelines have become more compressed
and prescriptive in terms of when and how long they occur. In response to the need to minimize
construction windows, DOTs have developed several accelerated bridge
construction (ABC) tools that are focused at reducing construction duration and
disruption to traffic operations. One
aspect of the construction is the time required to erect bridge
substructures. In recent years, several
DOTs have developed Precast Bridge Elements and Systems (PBES) that are modular
concrete elements. These elements are typically
fabricated away from the construction site, brought to the site, and erected quickly. These precast concrete elements are generally
of high quality and with precise details that can be attained in a controlled
fabrication shop. However, the
connection details often depend on grouted couplers that are mated with field
placed reinforcement bars requiring a high degree of precision to successfully align
and attach the precast elements.
The use of grouted couplers
and associated tight tolerances add to the complexity, risk, and cost of using
these elements in an accelerated construction environment. These adverse aspects of the grouted coupler
connections may discourage DOTs from specifying PBES and may discourage
contractors from electing them as a tool in managing construction schedules and
As an alternative,
connections of PBES (piers and abutments) could be accomplished with the use of
short conventional reinforcement and Ultra High-Performance Concrete (UHPC). This type of connection incorporates shorter
reinforcement development lengths as resulting laps. If a practical connection could be developed
that assured the DOTs and contractors that the tight tolerances and complexity
of a grouted coupler joint could be avoided, there would be more desire and
willingness by DOTs and contractors to incorporate the PBES in projects.
There would be several
likely benefits with a simplified UHPC connection of PBES piers and abutments. They would include lower project risk of
erecting misalignment, opportunity for the contractor to fabricate the elements
with their own staff as opposed to purchase from a fabricator, shorter
construction windows by inclusion of PBES, and increased safety to contractor
staff and traveling public through reduced interaction of contractors and
traffic operations. Use of UHPC connections will make precast
elements more efficient and more desirable by industry. This could lead to wider acceptability and
more frequent use of PBES for substructure design and construction.
The objective of this research is to develop and
test the details for the connection of precast pier elements using UHPC. Connections typically made with mechanical or
grouted couplers will be detailed with UHPC connections that meet strength and
fatigue requirements of the PBES elements.
This research could also provide code guidance on development lengths of
reinforcement, shear strength of connection region to be incorporated into the
AASHTO LRFD Bridge Design Specifications.
The intent of this research is not to develop connection details that
are resistant to significant or extreme seismic loading.
The intent is to provide
complete set of information that would allow Dots to use alternate connection
details, applicable in seismic and non-seismic areas which are user friendly
and implementable in the field and accommodating large tolerances.
This work will help simplify and remove construction risk associated
with using PBES. This will lead to
greater acceptability by DOT owners and construction contractors. This will ultimately lead to contractor
buy-in on the use of PBES to deliver projects in shorter time frames with
details that do not represent risk in erecting.
New Connection Detail to
Connect Precast Column to Cap Beam using Ultra-High-Performance Concrete in
Accelerated Bridge Construction Applications Mohamadreza Shafieifar, Mahsa Farzad, Atorod Azizinamini
NCHRP 12-102 [Completed] AASHTO Guide Specification for ABC
Design and Construction
Study the existing inventory of State DOT ABC Projects that
utilize PBES Precast Bridge Elements to document details used by DOTs to
connect PBES. The FHWA National
ABC Project Exchange and available project and research data bases should
be utilized in developing and assessing the current inventory of ABC projects.
Identify a subset of pier and abutment connection
geometries representative of what has been utilized by DOTs in recent years.
This at minimum should include cap beam to column and column to foundation
Develop example connection details that utilize
UHPCs and model with appropriate analytical methods and software to determine
the structural behavior.
Develop and conduct laboratory tests that
examine and validate analytic model results relating to strength and
serviceability of UHPC connections for precast elements (piers and abutments)
as well as addressing the knowledge gap that currently exists for implementing the
developed details in practice.
Produce design and construction guidance of
connection details that are reflective of typical substructure geometries used
Develop AASHTO LRFD Bridge Design Specification
This research will give
bridge designers and contractors tools to implement UHPC connection details in
substructure elements. The use of PBES
will become more desirable by Owners, Designers, and Contractors by simplifying
the connection detail, removing the risks associated with alignment of grouted
couplers, and reducing the overall project risks to schedule and cost.
Increased frequency of inclusion of PBES piers and abutments in construction projects at lower costs. More frequent occurrence of contractors viewing PBES as lower risk and doing the fabrication of PBES in their own yards or on job sites with their own staff.
|Sponsoring Committee:||AFH40, Construction of Bridges and Structures
|Research Period:||24 - 36 months|
|RNS Developer:||William L. Oliva|
|Source Info:||William L. Oliva, William.email@example.com, (608) 266-0075|
Chief of Structures Development Section, Wisconsin Department of Transportation
Also sponsored by the AFF00(2) Accelerated Bridge Construction Joint Subcommittee of the Structures Section (AFF00) and Construction Section (AFH00)
|Index Terms:||Ultra high performance concrete, Concrete bridges, Precast concrete, Structural connection, Bridge construction, Bridge members, |
|Cosponsoring Committees:||AFF00, Structures Section; AFH00, Construction Section|
Bridges and other structures