LRFD Bridge Manual - Part III
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INTRODUCTION TO PART III
PRECAST/PREFABRICATED BRIDGE ELEMENTS
STANDARD DETAILS
i.
PURPOSE AND USE
The purpose of Part III of this Bridge Manual is to provide Designers with standard MassDOT
details for precast/prefabricated bridge elements and their connections as well as guidelines for their
use in bridge projects. These standard details were developed based on precast/prefabricated bridge
element details and connections that have been used not only on bridge projects in the
Commonwealth of Massachusetts but elsewhere across the country.
For definition purposes for Part III, precast elements are those that could have been constructed
in the field using cast-in-place concrete construction but were instead cast at a precaster’s shop and
delivered to the site to be assembled into the final bridge member. Prefabricated elements are
typically superstructure elements that are fabricated off site and that consist of integral deck and beam
segments which, when delivered to the field, are assembled with closure pours to form the bridge
superstructure with minimal additional field construction. These are typically NEXT D beams,
NEBT D beams, and PBU’s (Prefabricated Bridge Units).
The standard details provided in Part III show precast/prefabricated elements being used for as
many elements of a bridge as possible. For an actual project, precast/prefabricated elements should
be used for as many or as few bridge members as needed based on a practical consideration of the site
constraints, construction schedule, economics, etc. MassDOT does not require that the Designer use
these elements everywhere that Part III standard details show them being used. The purpose of using
precast/prefabricated elements is to reduce impacts to the traveling public by shortening the
construction duration of a bridge project. Thus, if based on the Designer’s evaluation, some elements
of the proposed structure are not on the critical path of the construction schedule or if using
conventional construction better suits the constraints of the site, then the Designer may elect to build
those elements using conventional methods. Chapter 2 of Part I of the Bridge Manual provides
additional guidance on the use of precast/prefabricated bridge elements.
ii.
PRECAST TRANSITIONS
MassDOT has made the standard highway guardrail transition with base a fully precast element.
Since it is now a standard for all projects, the precast transition details do not appear in Part III but are
found in Part II. However, Designers should be mindful that a precast highway guardrail transition
might not fit all sites and bridge configurations. In these situations, the Designer should specify that
the transition top and its base are to be cast-in-place and should detail them appropriately.
iii.
DESIGN AND DETAILING
The precast details provided in Part III have been developed using emulative design principles
from the details provided in Part II of this Bridge Manual. Emulative design is a process in which a
precast element is designed and detailed to “emulate” a cast-in-place element except that, where
construction joints are used in cast-in-place construction, these now become joints between
precast/prefabricated members where member continuity is made through mechanical connections
(e.g. grouted splice couplers, grouted pockets, etc.). In most cases, reinforcement and other details
LRFD Bridge Manual - Part III
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that are not required to fabricate the element are not shown in the Part III details. The Designer must
refer back to the Part II details to ensure that the prefabricated elements that make up the bridge
member have been properly and thoroughly designed and detailed.
iv.
JOIN TS A N D CLOS U RE POU RS
When assembling precast/prefabricated elements, these elements must not be placed in direct
contact with one another. It is important to provide joints that are filled with “non-shrink grouts,” or
closure pours that are filled with concrete, in order to connect precast/prefabricated elements together
or to connect them to cast-in-place concrete. These joints and closure pours serve two purposes. The
first purpose is to make a secure structural connection between two elements that transmits forces
and/or moments. The second, which is equally important in the assembly of precast/prefabricated
elements, is to give the Contractor a way to accommodate both fabrication and erection tolerances
while building the bridge structure in order to maintain the required geometry and critical elevations.
Part III provides permissible fabrication and erection tolerances. Designers need to pay attention
to these tolerances and include them on the Construction Drawings so that the elements can be
properly fabricated and erected. Furthermore, the majority of joints between precast/prefabricated
elements shown in Part III have variable dimensions. The variability of these joint dimensions is
intended to allow the Contractor a means of adjusting the structure as it is erected in order to prevent
the accumulation of error. The joint widths are a function of the minimum permissible joint width that
will allow grout placement, acceptable fabrication tolerance of adjacent elements, and the erection
tolerances of the elements.
v.
GROU TS A N D CLOS U RE POU R CON CRETE
The long term success and performance of bridges assembled from precast/prefabricated elements
depends primarily on good detailing and the durability of the connections between those elements.
This means that the concrete used in the closure pours and the “non-shrink grout” used in the joints
must be suitable for the intended use so that it can be counted on performing as intended for the life
of the structure. To date, Designers have used the term “non-shrink grout” without much
consideration or detailed specification of the actual material being used in the field.
Since these connections are a critical part of the structure, the Designer must not only consider
the mechanical properties of these materials, such as the compressive strength, but also the
constructability (e.g., free flowing or stiff, strength gain, etc.), durability (e.g., freeze-thaw
resistance), and bond properties for each connection. Currently, the MassDOT Qualified Products
List contains many non-shrink grouts that are used in a variety of applications, but some may not
provide the performance or durability that is required for the connection that they are being used in.
It is the Designer’s responsibility to specify the intended grout’s required performance as part of the
Special Provisions.
vi.
A S S EMB LY PLA N S
In accelerated construction projects, the role of the Contractor changes from being a builder to
being an assembler. For these projects, it is critical that the Contractor develops and submits an
Assembly Plan prior to the start of the work. An Assembly Plan is a document prepared by the
Contractor working with their qualified Engineer that outlines the steps that the Contractor will
follow in “assembling” the structure. In addition to the sequence of operations, the Assembly Plan
must also include the equipment, materials, and schedule that the Contractor shall use. It should also
include data sheets for all pre-bagged non-shrink grouts that will be used in the assembly and should
LRFD Bridge Manual - Part III
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demonstrate that the performance of these materials, such as required strength gain within the time
allotted, is compatible with the intended assembly schedule. Once submitted, Designers shall review
the Assembly Plan as they would any other construction procedure for a MassDOT project.
vii.
A LTERN A TE CON N ECTION D ETA ILS
In many situations, there may be several methods for connecting two precast elements. In
developing the Part III details, MassDOT has standardized on those methods that have proven
effective on previous MassDOT construction projects using precast/prefabricated elements.
However, Designers, Contractors and Fabricators may want to use other methods for a variety of
reasons, including cost, assembly schedule, etc. For this reason, MassDOT has reviewed the FHWA
Publication No. FHWA-IF-09-010 titled, “Connection Details for Prefabricated Bridge Elements and
Systems,” and summarized all those alternate connection details that MassDOT finds acceptable in
the Tables below. This FHWA Publication that is available through the FHWA website. Table i-1
includes connection details for superstructures and Table i-2 includes connection details for
substructures. The detail numbers in the referenced tables correspond to the detail numbers in the
FHWA Publication. All details provided in the Tables below may be used, where applicable,
however the Designer, Contractor or Fabricator shall assume full responsibility for the design,
detailing, and constructability of these alternate connections if used on the project.
LRFD Bridge Manual - Part III
Connected Bridge Superst ructure Components
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Detail Number
Full Depth Precast Concrete Deck Panel to Full Depth Precast Concrete Deck Panel
Full Depth Precast Concrete Deck Panel to Full Depth Precast Concrete Deck Panel
Full Depth Precast Concrete Deck Panel to Full Depth Precast Concrete Deck Panel
Full Depth Precast Concrete Deck Panel to Full Depth Precast Concrete Deck Panel
Full Depth Precast Concrete Deck Panel to Full Depth Precast Concrete Deck Panel
2.1.1.1 B
2.1.1.1 C
2.1.1.1 D
2.1.1.2 I
2.1.1.2 J
Full Depth Precast Concrete Deck Panel to Steel Girder
Full Depth Precast Concrete Deck Panel to Steel Girder
Full Depth Precast Concrete Deck Panel to Steel Girder End Diaphragm
Full Depth Precast Concrete Deck Panel to Steel Girder
Full Depth Precast Concrete Deck Panel to Steel Box Girder
2.1.1.2 A
2.1.1.2 B
2.1.1.2 C
2.1.1.2 D
2.1.1.2 E
Full Depth Precast Concrete Deck Panel to New Precast Prestressed Beam
Full Depth Precast Concrete Deck Panel to Existing Precast Prestressed Beam
Full Depth Precast Concrete Deck Panel to Pr ecast Prestressed Beam
2.1.1.3 B
2.1.1.3 C
2.1.1.3 F
Full Depth Precast Concrete Deck Panel to C.I.P. Concrete Barrier
Full Depth Precast Concrete Deck Panel to C.I.P. Concrete Barrier
2.1.1.4 A
2.1.1.4 B
Precast Concrete Deck Sub-Panel (SIP form) to Steel Girder
2.1.5.1 A
Precast Concrete Deck Sub-Panel (SIP form) to Precast Prestressed Beam
2.1.5.2 A
Steel Diaphragms to Precast Concrete NE B ulb Tees
Steel Diaphragms to Precast Concrete NE B ulb Tees
Precast Concrete Intermediate Diaphragm to Precast Concrete NE Bulb T ee
2.3.1.2 B
2.3.1.2 C
2.3.1.2 D
Steel Girder to Steel Girder
2.3.3.2 A
Precast Concrete Arch Section to Precast Concrete Arch Section
Precast Concrete Arch Section to Precast Concrete Arch Section
2.4.3.1 A
2.4.3.2 A
Precast Concrete Spandrel Wall to Precast Concrete Arch Section
Precast Concrete Spandrel Wall to Precast Concrete Arch Section
2.4.3.3 A
2.4.3.3 B
Precast Concrete Wall Stem to Precast Concrete Footing
Precast Concrete Arch Section to Precast Concrete Footing
Precast Concrete Wingwall to Precast Concrete Footing
Precast Concrete Wingwall to Precast Concrete Arch
Precast Concrete Arch Section to C.I.P. Concrete Footing
2.4.3 A
2.4.3 B
2.4.3 C
2.4.3 D
2.4.3 E
Precast Concrete Box Culvert to C.I.P. Cutoff and Return Wall
Precast Concrete Box Culvert to C.I.P. Nose and Footing
Precast Concrete Box Culvert Section to Precast Concrete Box Culvert Section
2.4.4 A
2.4.4 B
2.4.4 C
Precast Concrete Rectangular Column to C.I.P. Concrete Pier Cap
2.5.1 A
Precast Concrete Beam to Pr ecast Concrete Integral Abutment
2.5.2 A
Precast Concrete Box Beam to Precast Concrete Semi-Integral Abutment Stem
2.5.3 C
Precast Concrete Parapet to C.I.P. Concrete Deck
2.6.2 C
Table 1: List of MassDOT Preferred Superstructure Connections
Tabl e i -1 : Li s t o f M as s D OT Pre f e rre d S upe rs truc ture C o nne c ti o ns
LRFD Bridge Manual - Part III
Connected Bridge Substructure Components
i-5
Detail Number
Precast Concrete Pier Cap to C.I.P. Concrete Column
Precast Concrete Pier Cap to C.I.P. Concrete Column
3.1.1.1 B
3.1.1.1 C
Precast Concrete Pier Cap to Precast Concrete Column
Precast Concrete Pier Cap to Precast Concrete Column
3.1.1.2 B
3.1.1.2 D
Precast Concrete Pier Cap to Steel Pipe Pile
3.1.1.3 A
Precast Concrete Pier Cap to Precast Prestressed Hollow Concr ete Square Pile
3.1.1.4 A
Precast Concrete Pier Cap to Prestressed Concr ete Pile
Precast Concrete Pier Cap to Prestressed Concr ete Pile
3.1.1.4 C
3.1.1.4 D
Precast Concrete Pier Cap to Precast Concrete Pier Cap
3.1.1.5 A
Precast Concrete Pier Column to Pr ecast Concrete Pier Column
Precast Concrete Pier Column to Pr ecast Concrete Pier Column
3.1.2.1 A
3.1.2.1 B
Precast Concrete Wall to Precast Concrete Spread Footing
3.1.3.1 A
Precast Concrete Pier Column to C.I.P. Concrete Footing
Precast Concrete Rectangular Pier Column to C.I.P. Concrete Footing
3.1.4.1 B
3.1.4.1 C
Precast Concrete Pier Column to Pr ecast Concrete Spread Footing
Precast Concrete Pier Column to Pr ecast Concrete Spread Footing
3.1.4.2 A
3.1.4.2 B
Precast Concrete Pier Column to Pr ecast Concrete Spread Footing
3.2.1.1 A
Precast Concrete Backwall to Precast Concrete Abutment
3.2.1.2 A
Precast Concrete Cheekwall to Precast Concrete Abutment
3.2.1.3 A
Precast Concrete Semi-Integral Abutment to Steel Piles
3.2.3.1 B
Precast Concrete Abutment Cap to Pr estressed Concrete Pile
3.2.3.2 C
Precast Concrete Semi-Integral Abutment Stem to Precast Concrete Semi-Integral Abutment Stem
3.2.3.3 A
Precast Concrete Semi-Integral Abutment Stem to Precast Concrete Flying Wingwall
3.2.4.1 A
Precast Concrete Abutment/Backwall to Precast Concr ete Approach Slab
3.2.4.2 A
Precast Concrete Wall Stem to Precast Concrete Footing
3.3.1.1 A
Precast Concrete Footing to Subgrade
4.1.1 A
Precast Concrete Footing to Precast Concrete Footing
4.1.2 A
Precast Prestressed Concrete Square Pile to Precast Pile Cap
4.1.4 A
Precast Concrete Spread Footing to Precast Concrete or Steel Pile
4.1.4 B
Table 2: List of MassDOT Preferred Substructure Connections
Tabl e i -2 : Li s t o f M as s D OT Pre f e rre d S ubs truc ture C o nne c ti o ns