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ACI 550.2R-13
Design Guide for Connections in
Precast Jointed Systems
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Reported by Joint ACI-ASCE Committee 550
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American Concrete Institute®
Advancing concrete knowledge
Design Guide for Connections in Precast Jointed Systems
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ACI 550.2R-13
Design Guide for Connections in Precast Jointed
Systems
Reported by Joint ACI-ASCE Committee 550
Thomas J. D’Arcy, Chair
Te-Lin Chung
Ned M. Cleland
William K. Doughty
Alvin C. Ericson
Melvyn A. Galinat
Harry A. Gleich
Mohammad S. Habib
Neil M. Hawkins
Augusto H. Holmberg
L. S. Paul Johal
Jason J. Krohn
Emily B. Lorenz
Kenneth A. Luttrell
Vilas S. Mujumdar
Frank A. Nadeau
Clifford R. Ohlwiler
Victor F. Pizano-Thomen
Jose I. Restrepo
3.5—Debonding, p. 7
The proper detailing and design of precast concrete connections
are essential to the performance of a precast concrete structure.
This guide provides information on design, detailing, and construction of connections between precast members in jointed systems,
including moment frame and structural wall systems.
CHAPTER 4—PRECAST CONCRETE FLOOR
SYSTEMS, p. 7
4.1—Precast systems, p. 7
4.2—Precast floor diaphragms, p. 7
Keywords: bolting; connection; debonding; ductility; erection; moment
frame; precast; pretopped; post-tensioning; structural walls; welding.
CHAPTER 5—LATERAL-LOAD-RESISTING
SYSTEMS, p. 8
5.1—Structural walls, p. 8
5.2—Structural walls with large openings, p. 8
5.3—Moment frames, p. 8
CONTENTS
CHAPTER 1—INTRODUCTION AND SCOPE, p. 2
1.1—Introduction, p. 2
1.2—Scope, p. 2
CHAPTER 6—CONNECTIONS, p. 10
6.1—Strength, p. 10
6.2—Ductility, p. 10
6.3—Volume change accommodation, p. 11
6.4—Durability, p. 11
6.5—Fire resistance, p. 11
6.6—Constructibility, p. 11
6.7—Aesthetics, p. 11
6.8—Seismic requirements, p. 11
6.9—Tolerances, p. 11
6.10—Vertical connections, p. 11
CHAPTER 2—NOTATION AND DEFINITIONS, p. 2
2.1—Notation, p. 2
2.2—Definitions, p. 2
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CHAPTER 3—GUIDELINES FOR DESIGN, p. 3
3.1—Classes of connections, p. 3
3.2—Principles of connection design, p. 3
3.3—Anchorage to concrete, p. 5
3.4—Welding, p. 5
ACI Committee Reports, Guides, and Commentaries are
intended for guidance in planning, designing, executing, and
inspecting construction. This document is intended for the use
of individuals who are competent to evaluate the significance
and limitations of its content and recommendations and who
will accept responsibility for the application of the material it
contains. The American Concrete Institute disclaims any and
all responsibility for the stated principles. The Institute shall
not be liable for any loss or damage arising therefrom.
Reference to this document shall not be made in contract
documents. If items found in this document are desired by
the Architect/Engineer to be a part of the contract documents,
they shall be restated in mandatory language for incorporation
by the Architect/Engineer.
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Sami H. Rizkalla
Mario E. Rodriguez
Joseph C. Sanders
John F. Stanton
P. Jeffrey Wang
Cloyd E. Warnes
CHAPTER 7—ERECTION CONSIDERATIONS, p. 13
CHAPTER 8—WELDING CONSIDERATIONS, p. 13
8.1—Steel assemblies, p. 13
ACI 550.2R-13 was adopted and published April 2013.
Copyright © 2013, American Concrete Institute.
All rights reserved including rights of reproduction and use in any form or by any
means, including the making of copies by any photo process, or by electronic or
mechanical device, printed, written, or oral, or recording for sound or visual reproduction or for use in any knowledge or retrieval system or device, unless permission in
writing is obtained from the copyright proprietors.
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DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
8.2—Galvanized steel, p. 13
8.3—Stainless steel, p. 14
8.4—Reinforcement, p. 14
8.5—Welding practices for epoxy-coated material, p. 15
CHAPTER 9—GROUTING, p. 15
CHAPTER 10—REFERENCES, p. 15
CHAPTER 1—INTRODUCTION AND SCOPE
1.1—Introduction
Precast concrete structural systems are composed of individually fabricated components. Because of the segmental
nature of precast concrete construction, connections between
individual components are required to support the design
loads. Connections are also required to accommodate deformations, including rotations and strains.
1.1.1 Connection methods—Precast components are
connected by one of two methods. The first method connects
components by reinforcement that protrudes from each
component end, spliced using proprietary hardware or by
lap-splicing with a small quantity of cast-in-place concrete
to complete the connection. This method is referred to as
emulation, or a wet connection, because it involves fieldplaced cast-in-place concrete and mimics the behavior of
cast-in-placed monolithic structures. The second, morecommon, method of connection is dry and connects components by welding, bolting, post-tensioning, or doweling
without using field-placed concrete. Because dry connections are typically less stiff than their connecting precast
components, deformations tend to be concentrated in the
connections.
Connections should allow for easy and economical
component casting and assembly, fabrication, erection clearance, and erection tolerances. They should also tolerate
anticipated deformation without significant loss of strength.
1.1.2 Connection groups—Connections are categorized
into five groups:
1) Gravity load transfer—Gravity loads alone, such as
hollow core members placed on a beam ledge
2) Shear transfer—Either vertical shear, horizontal shear,
or both, such as a double-tee flange-to-flange connection
3) Moment transfer—The tension and compression
forces created by moment, such as a connection between a
precast moment frame and its foundation
4) Structural integrity—Code-prescribed structural
integrity forces; typically a connection with combination
accommodations
5) Combination connection—A combination of loads,
such as moments and shear
In all cases, the load paths and external loads are accommodated in all elements of connections (Fig. 1.1.2).
Tying all precast members to each adjacent member is
essential for structural integrity as required by Chapter 16
of ACI 318-11. Such connections, however, should not be so
rigid as to prevent member rotation or volume change strains
when required.
Fig. 1.1.2—Wall panel to foundation connection.
1.2—Scope
This guide provides information on the characteristics and
design of connections between precast concrete components
and between precast components and cast-in-place construction. The proper detailing and design of precast concrete
connections are essential to the performance of a precast
concrete structure.
This guide describes typical precast jointed systems and
their connection types, performance, and characteristics,
and provides recommendations for design and construction. Three classes of connections are identified and their
characteristic and key design considerations given. Also
included are guidelines for designing connections and their
anchorage, a description of precast systems, typical lateralload-resisting systems, key design considerations, and erection requirements including special welding considerations.
CHAPTER 2—NOTATION AND DEFINITIONS
2.1—Notation
Cd = deflection amplification factor
fc′ = specified compressive strength of concrete, psi
(MPa)
R = response modification factor
f = strength reduction factor
2.2—Definitions
ACI provides a comprehensive list of definitions through
an online resource, “ACI Concrete Terminology,” http://
terminology.concrete.org. Definitions provided herein
complement that resource.
deformable connection—a class of connection between
precast members designed to either display significant flexibility or to yield, without losing strength, when subjected to
expected deformations.
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DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
ductile connection—a class of connection between
precast members designed to yield and show stable hysteretic force-deformation response when subjected to expected
reversed cyclic deformations.
joint—the location in a precast structural system where
precast members intersect.
gravity-only member—a member of a framing system
that supports mainly gravity loads and is not part of the
lateral-load-resisting system.
pretopped system—a precast flooring system that
employs a thickened top flange on precast members (typically double tees) provided in place of field-placed topping.
strong connection—a class of connection between
precast members in which the connection between precast
members remains elastic while adjoining members experience yielding when subjected to expected deformations.
CHAPTER 3—GUIDELINES FOR DESIGN
3.1—Classes of connections
Selection of the connection type between precast components is essential to precast concrete design. Connection
types should be identified early in the design process based
on their expected role in the structural system. Yielding of
reinforcement is common in reinforced concrete structures
in response to severe forces such as earthquakes. Designers
should consider the location of inelastic deformation in
components and design them to accommodate the deformations without loss of service strength. The joint regions
where precast members come together are the most likely
place for yielding in frames. In emulative concrete construction, they are rendered ductile by the prescriptive detailing
requirements of the International Building Code (IBC 2006).
Three classes of connections are described: strong, ductile,
and deformable.
3.1.1 Strong—Strong connections use a hierarchical
design approach to ensure yielding and strain hardening will
take place away from the connection. Strong connections do
not have to display ductile response. The absolute strength
is less important than the ratio of capacity to demand. An
example is a one-piece beam and column precast component connected at midspan of the beam. When the seismic
moments at midspan are smaller than at support locations,
yielding occurs in the precast beam at the column face. This
approach is not employed as frequently as other solutions.
The concept of creating strong joints to force yielding in
the precast members away from the joint, although feasible,
is typically used where jointing occurs at frame inflection
points (Fig. 3.1.1).
3.1.2 Ductile—Ductile connections, which possess significant deformation capacity, are detailed in regions where
inelastic deformations concentrate to form a part of the
seismic-load-resisting system. Ductile connections display
stable hysteresis loops when subjected to reversed cyclic
loading. Their design follows a strength hierarchy to ensure
yielding and cyclic strain hardening occurring at the connection only. Such connections can be welded; however, the
strength of welds and embeds need to be stronger than the
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Fig. 3.1.1—Precast moment frame with connection made in
column away from beam-to-column joints.
connecting plate. Ductile connections can also be made with
splicing reinforcing bars by lapping or using proprietary
splice sleeves. There should be sufficient strain capacity to
sustain resistance through the required movement.
3.1.3 Deformable—Deformable connections undergo
deformations when the structure displaces. For example, a
precast beam bearing on a rubber pad on a corbel allows
rotation with little longitudinal resistance. Although rotation
occurs, the vertical load-carrying strength is not impaired.
The gravity-only members and connections in many
seismic-resistant structures—precast and otherwise—should
act this way. In the 1994 Northridge earthquake, a number of
connections lost their integrity because they relied on gravity
to remain in place (Iverson and Hawkins 1994). Under a
horizontal load, unseating of deformable connectors should
be prevented; therefore, where movement is expected, some
measure of restraint is required. Note that in Fig. 3.1.3,
the connection’s vertical support is maintained, but lateral
movement is limited by the threaded rod in the sleeve.
3.2—Principles of connection design
An appropriate connection detail can be designed once
its function has been defined. Use of the three classes of
connections enables the designer to plan the behavior of
the structure, rather than using distributed toughness in the
structure to cover all potential behaviors, as is largely done
in cast-in-place construction.
To achieve that goal, seven design principles (3.2.1
through 3.2.6) are recommended in this guide
1) Relate connections to the system
2) Provide a complete load path through the system
3) Avoid eccentricities in load paths where possible
4) Use capacity design to control the behavior of the
connection (PCI Committee on Connection Detail 1995,
1998), which is the preferred method; however, strut and tie
design methodology is also employed in precast concrete
design practice with good results and performances
5) Provide for ductility where needed
6) Account for energy dissipation where required
7) Consider constructibility
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DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
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Fig. 3.1.3—Doweled beam connection (PCI 2008).
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DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
3.2.1 System connections—The connections control the
way a structure behaves so they should be consistent with
the complete structural system. For example, in a panel
structure, two possible forms of response are rocking at the
base or sliding at joints. The designer should decide how the
structure should act, rather than only calculating code forces
and design connections to ensure that the desired behavior
occurs and loads are transferred to the foundations. Rocking
at the base or in subsequent panel joints is the preferred solution rather than sliding displacement of the joints.
3.2.2 Load path—A complete load path should be
provided for all forces to be transmitted from their point of
origin to the foundation and each link in the path judged for
adequacy. Compression segments of the path are seldom
a problem because of their large surfaces areas and that
component ends are typically armored with bearing plates.
Tension and shear segments are more likely to prove critical
because of their tendency to crack members at or near the
connection region.
3.2.3 Load path eccentricity—Offsets in tension load
paths create moments that tend to straighten the member
or bend the connections; offsets in compression load paths
tend to bend members. Such offsets should be avoided or
arrangements made to ensure that the moments are resisted
by another component. A common example of an offset is
a reinforcing bar fillet welded to a plate. If the rotation is
not suppressed, this detail is potentially dangerous because,
under load, the bar is sharply bent immediately adjacent
to the weld, with the possibility of embrittlement. In tests
(Stanton et al. 1986), a bar detailed in such a manner fractured without any necking down.
3.2.4 Capacity design—Capacity design is a hierarchical design approach that enables a designer to control
the response of a component or a structure as a whole. This
approach was first suggested by Park and Paulay (1975). To
ensure that yielding occurs in the designated ductile element
of the load path, that element should be the weakest link
in the connection. Suitable safety factors should be used
in designing the adjacent elements not required to display
ductility to protect them against yielding. Some overstrength
factors are provided in governing codes.
Some common means of connecting steel rods or bars,
such as welding or threading, may weaken the connecting
element and concentrate the inelastic deformations in
the anchorage to the concrete. Failure of the anchorage is
undesirable because of its difficulty to repair. Deliberately
reducing the connecting element section at a location away
from the attachment is one way of providing for greater
deformation capacity. An example is shown in Fig. 3.2.4a.
A rectangular field splice plate, used to connect two panels
in shear, proved stronger than the weld and the anchorage to
the concrete when no special measures were taken (Stanton
et al. 1986). Failure was brittle and was initiated by fracture
of the weld and by pullout of the embedded bars. A modified
plate, equipped with slots to reduce the section and circular
ends to avoid stress concentrations at the slot ends in the
connecting plate, as shown in Fig. 3.2.4b, could provide
significant ductility. The connection failed by yielding and
5
fracture of the plate and protected the anchorage and the
weld. Replacement of the damaged plate after an earthquake
would also be relatively simple.
3.2.5 Ductility—Particularly in structures exposed to the
elements, where temperature change strain occurs, ductile
connections (refer to 3.1.2) should be designed and detailed
to provide for ductility and the ability to yield without
damage to adjacent concrete surfaces.
3.2.6 Constructibility—Connection design should
consider the following: standardize connections within a
project; use standard hardware items; avoid non-standard
production and erection tolerances; provide accessibility;
consider constructibility; provide for field adjustment; and
avoid penetration of forms.
3.3—Anchorage to concrete
As noted in 3.2.4, it is best to provide yielding in the
connecting element to minimize or eliminate cracking.
Anchorage of steel embedments to concrete requires careful
consideration. The anchorage length has to be considered,
because yielding of bars implies cracking in the concrete.
Even if the bar does not yield, cracking may still occur
because compatibility of strains in the two materials means
that the concrete cracks when the steel stress is approximately 5 ksi (35 MPa). This indicates that calculating
bar sizes and embedment lengths on the basis of strength
at factored loads will almost certainly lead to concrete
damage. For example, if the angle embedded in the concrete
in Fig. 3.2.4a is attached to bars embedded in the concrete
and capacity design concepts are used with a factor of 1.5
to protect the anchorage, the bar stress will still be 40 ksi
(275 MPa) when the field plate yields. That stress is 80
times the 500 psi (3.5 MPa) at which concrete cracking is
expected to start. This yielding occurs when the connection
is in tension. The bars should have adequate development in
the surrounding concrete. The concrete adjacent to the bar
may crack if the bar stress results in deformation that leads
to concrete cracking. The strut-and-tie method (ACI 318)
offers a rational way to choose loads and force path in the
vicinity of connections.
The best performance of a connection eliminates cracking.
Possible ways to control cracking include prestressing the
concrete, debonding the bars with sufficient length of bar
beyond the debonded region to ensure full development,
or using a mechanical anchor or hooked bars to cause
compression on the far end of the concrete rather than
tension. Debonding minimizes tension at the member face
by allowing uniform strain in the reinforcement in the
debonded region. If pretensioning is used, the determination
of a potential cracking region should account for the transfer
length for the prestressing steel.
3.4—Welding
Welding alters the physical properties of steel and can
cause embrittlement. Before the 1994 Northridge earthquake
(Iverson and Hawkins 1994), it was generally believed that
a properly designed and executed weld in a structural steel
frame could withstand cyclic yielding. Materials with high
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DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
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6
Fig. 3.2.4a—Welded connection (PCI 2008).
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DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
7
CHAPTER 4—PRECAST CONCRETE FLOOR
SYSTEMS
Fig. 3.2.4b—Modified connection to provide more ductility.
carbon equivalent susceptible to improperly made welds
were more likely to have problems (ASTM A615/A615M;
Rodriguez and Rodriguez 2006). Because of this, steel
framing connections in hundreds of steel-framed structures
damaged during the Northridge earthquake were altered to
provide for a more gradual load transfer.
Welds should not be used adjacent to a potential yield
region or a reinforcing bar bend. Because welding is almost
impossible to avoid altogether, detailing of embeds should
ensure that the potential yield zone does not impinge on
the weld. Welding considerations are discussed in detail in
Chapter 8.
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3.5—Debonding
Deliberate local debonding can relieve local strain concentrations and subsequent fracture. Bars that are grouted into
ducts do not debond as readily as those cast directly into
concrete, so the possibility of premature fracture exists.
This was verified in beam-column tests (Cheok and Stone
1994). Bars were grouted into ducts in the beam and column.
At large story drifts of ±3 percent, the bar elongation was
considerable but was forced to occur over only a short
unbonded length of approximately 4 in. (100 mm). The local
strain was very high and the bars fractured.
The debonded length should be properly selected and
designed as part of the connection. At a length that is too
short, the bars fracture; at a length that is too long, the
bars never yield and energy is not dissipated. Typical reinforcing bar debonding lengths are 4 to 8 in. (100 to 200
mm) or four to eight bar diameters. Debonding can be
achieved by placing a sleeve over the reinforcing bar, held
in place with tape. Tests of precast hybrid frames (beam
and column systems) have shown that the debonded length
can be determined reliably (Schoettler et al. 2008; Priestley
et al. 1999).
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4.1—Precast systems
Precast concrete floor systems are typically constructed
with double-tee or hollow-core members with a cast-inplace topping that is 2 to 3 in. (50 to 75 mm) thick. Double
tees may also be pretopped where the flange is cast thicker—
typically 4 in. (100 mm)—thereby incorporating the topping
in the thicker precast flange. Deck members are typically
supported by beams, spandrels, or wall panels. In pretopped
applications, field pour strips are typically provided over the
beams to provide field fit-up tolerances.
4.1.1 Topped systems—Double-tee or hollow-core floor
members are erected and a field-placed topping is applied.
The topping acts compositely with floor members. It is cast
a minimum of 2 in. (50 mm) thick at center span, and either
follows the camber or creates a thicker topping at the bearing
ends. A minimum fc′ of 3500 psi (24 MPa) is recommended.
Topping and deck thickness may also be dictated by fire
rating requirements.
To control shrinkage cracking in parking structures, the
topping over each precast-to-precast member joint is tooled
and the joints are sealed (Fig. 4.1.1). Proper curing of the
topping is essential to control shrinkage cracking. The
precast member surface is cleaned and moistened before
placing the topping. Diaphragm reinforcement and temperature and shrinkage reinforcement are placed within the
topping. Controlling the concrete topping mixture and alternating topping placement in a checkerboard pattern on the
floors to break up long shrinkage paths helps to minimize the
effects of topping shrinkage. Fiber reinforcement has also
been used to control shrinkage cracking (ACI 544.1R-96).
4.1.2 Pretopped systems—To minimize the use of fieldplaced concrete and to provide the highest quality concrete
at the wearing surface, double-tee flanges are cast 4 in.
(100 mm) or more in thickness in the precast plant. This
system is typically used for parking structures in cold or
aggressive environments.
Hollow-core planks are also used without field-placed
topping, but the top flange is not thickened. Such systems
are typical in housing applications.
Pretopped double-tee systems rely on flange-to-flange
welded connections to transfer shear and create a diaphragm.
Diaphragm chord reinforcement is located in end-member
pour strips. In locales where lateral loading requirements are
low, flange-to-flange welded connections are occasionally
employed (Schoettler et al. 2008).
4.2—Precast floor diaphragms
Precast floor diaphragms should be connected to the
seismic-load-resisting elements such as walls. The connection can be achieved in several ways, including welding,
bolting, or dowel action. Dowels that extend from the
seismic-load-resisting element and are anchored into the
diaphragm by cast-in-place concrete should have sufficient
length to be developed in the diaphragm.
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DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
Fig. 4.1.1—Tooled joint.
CHAPTER 5—LATERAL-LOAD-RESISTING
SYSTEMS
5.1—Structural walls
Structural walls are the most common system used in
precast structures to resist lateral loads. The success of this
system in many earthquakes around the world indicates that
it is a viable solution. The typical design takes advantage of
existing bearing walls either in shafts, parking deck ramp
walls, or interior or exterior walls. In some applications,
precast walls are connected to form stiffer shapes, such as
boxes or cruciforms.
Precast structural walls are connected by several means,
depending on the design lateral force level. Bolting, welding,
or dowel connections are used for the lower seismic force
levels that prevail in the U.S. (Fig. 5.1a, typical dowel
connection) for shear wall connections.
For higher seismic force levels, post-tensioning or reinforcing bar splice mechanisms are used to connect the
precast panels to their foundation or to each other, following
the requirements of Chapter 21 of ACI 318-11. The critical connection in wall systems is usually the connection
between the precast panel and the cast-in-place foundation.
This is the location of maximum shear and moment caused
by lateral loads.
The University of California, San Diego (UCSD) PRESSS
project (Fig. 5.1b) tested a five-story, all-precast structural wall system connected with unbonded vertical posttensioning with excellent results (Priestley et al. 1999).
The five-story walls were connected vertically along panel
sides with highly ductile welded connections that allowed
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Fig. 5.1a—Wall panel dowel connection to footing.
the panels to rock about their base with little damage to the
panels. The vertical unbonded post-tensioning righted the
panel after lateral loading as described in ACI ITG-5.1.
In parking structures, solid walls have been replaced with
panels with large openings for increased visibility and personal
safety. These panels can be connected as described previously.
Structural wall systems can be constructed with long
horizontal walls (20 to 45 ft [6 to 13.5 m] wide) or narrow
vertical walls (7 to 12 ft [2 to 3.5 m] wide). In the latter
system, the walls are typically pretensioned.
Horizontal joints in panel-to-panel connections typically
contain a combination of grout to resist compressive forces
through the joint plus various means of connection to resist
the uplift or tension force. In regions of low seismic demands,
wind loads may govern the design, and the tension connection is typically a welded, bolted, or doweled connection,
as shown in Fig. 3.2.4b and 5.1a. In higher seismic regions,
codes require that a ductile, or Type 2, splice connection be
employed. Reinforcing bar splice assemblies are often used
(ACI 550.1R). Post-tensioning may also be used as a nonemulative method of connection that does not replicate the
performance of cast-in-place concrete.
5.2—Structural walls with large openings
In parking structures where solid structural walls are undesirable because of personal safety concerns, large openings
are placed in the structural walls for visibility. The column
and beam elements of the wall around an opening are still
relatively large in size and are designed to withstand the
shears and overturning moments acting on them. Wall piers,
which are similar to columns, have an aspect ratio of at least
2.5 length-to-width.
5.3—Moment frames
Precast moment frames take advantage of a larger
response modification factor R as compared with the lower
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Continuous reinforcement should be used in the diaphragm
to transfer seismic loads to the seismic-load-resisting elements.
Topping reinforcement in composite systems should provide
sufficient ductility to accommodate floor drift.
Perimeter chord reinforcement is typically used to resist
seismic tension and moment forces, and flange connections
between double tees typically resist shear forces. Preliminary
findings on the performance and design of precast concrete
floor system diaphragm are available. The research includes
a 1/2-scale, three-story building subjected to seismic loading
on a large shake table (Schoettler et al. 2008).
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DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
9
Fig. 5.1b—PRESSS test structure with wall panel connection.
R-value for structural walls. Precast moment frames are also
used for more open structures and to provide more open
parking structures. They can be created by either casting
beams to their supporting columns to create several shapes
(Fig. 5.3) or connecting the frames vertically to one another
or by connecting the individual beams to columns with field
connections.
ACI 318 and IBC 2006 provide three categories of
moment frames:
1) Ordinary: R = 3, Cd = 2-1/2
2) Intermediate: R = 5, Cd = 4-1/2
3) Special: R = 8, Cd = 5-1/2
The response modification factor, which directly affects
the base shear, is significantly different for each frame type.
Increasing the R-value requires more rigorous reinforcement detailing to achieve the more ductile performance
of the frame implied by the higher R-value. Increasing the
R-value increases the degree of difficulty for both design and
Fig. 5.3—Combination of beams and columns to create a
moment frame.
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10
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detailing, but yields a significant reduction in the base shear,
which can yield significant savings in the overall seismicload-resisting system. Lateral drift limits remain the same for
all frame systems. The Cd multiplier increases with system
ductility so the elastic displacement of ductile systems is lower.
ACI 318 provides design requirements for the three aforementioned frame types. As required by ACI 318, the designer
should, for the special moment frame connections, emulate
a cast-in-place moment frame with either Type 2 reinforcing
bar splice assemblies or post-tensioning.
5.3.1 Ordinary frame—The ordinary frame is designed for
Seismic Design Categories A and B (ASCE/SEI 7-05) and
only needs to meet the requirements in ACI 318-11, Chapters 1 to 18. Typical precast moment frame shapes are shown
in Fig. 5.3, and a moment frame is shown in Fig. 5.3.1.
5.3.2 Intermediate and special frames—Frames in higher
seismic activity regions are typically connected using reinforcing bar splice components. Section 21.6 of ACI 318-11
provides requirements for the design of special moment
frames constructed using precast concrete. As noted, precast
moment frames not meeting these criteria should follow
ACI T1.2/T1.2M and ACI 374.1. This requires control of
dowel bar installation in the cast-in-place foundation, which
is accomplished by using templates fabricated and installed
to maintain tight tolerances. The dowel bars are installed in
the precast member or in the mating cast-in-place element.
When the project superintendent is informed that the required
tolerances for the dowels is ±1/4 in. (±6 mm), which is more
stringent than ACI 117 and ACI ITG-7, successful placement of dowel bars can be achieved. As many as 24 sleeves
per frame have been used successfully. Bars should be held
in place with a bi-level template both above and below the
concrete surface to keep them straight and oriented properly.
An oversized sleeve by up to two bar sizes can be cast in
the foundation to allow for extra tolerance. The cast-in-place
embedded bars are detailed longer than required and sawed
to the required length after the concrete has set. Note that
ACI 318 requires that reinforcement in ductile connections
be made continuous by using Type 2 mechanical splices that
provide development in tension or compression of at least
150 percent of the specified yield strength of the bars.
Special moment frames should be designed in accordance with Chapter 21 of ACI 318-11. Examples of special
reinforcement requirements are 135-degree hooks and
maximum spacing of transverse reinforcement of 6 in.
(150 mm) over a specified length at each end of members.
Other special requirements include maximum spacing of
crossties, special requirements for development length of
reinforcing bars, shear strength, and confining reinforcement. The general intent is to produce a member according
to ACI 318-11 design requirements with adequate toughness
for this special response.
CHAPTER 6—CONNECTIONS
Design criteria for connections in precast concrete should
be selected on the basis of the connections’ intended function. Because the functions vary, different criteria will apply
to different types of connections.
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Fig. 5.3.1—Example of precast moment frame.
6.1—Strength
Connections should be designed to transfer the forces to
which they will be subjected during their lifetime. These
forces include those caused by volume change and those
required to maintain stability.
In terms of flexure, axial load, shear, and torsion, the
design strength of a member’s connections should be taken
as the nominal strength calculated in accordance with ACI
318, multiplied by a strength reduction factor f. PCI (2008)
provides detailed information on connection design.
Strength reduction factors f are provided in Section 9.3 of
ACI 318-11:
Tension controlled sections..........................................0.90
Compression controlled sections:
Members with spiral reinforcement..........................0.70
Other reinforced members............................................0.65
Shear and torsion..........................................................0.75
Bearing on concrete......................................................0.65
The f factors for steel construction are provided in AISC
325-05.
Tension and shear.........................................................0.90
Welds............................................................................0.75
Bolts and threaded fasteners.........................................0.75
6.2—Ductility
Ductility of a connection is the ability to undergo relatively large, inelastic deformations before failure. In structures, ductility is measured by the amount of deformation
between first yield and failure. Ductility in the overall structure may result from the ductility of the structural members,
their connections, or both. In precast concrete structures,
connection ductility can be used to contribute to the overall
structure ductility. Connection ductility is achieved by
ensuring that embedded load-transfer elements, such as
deformed bar and headed stud anchors, welded wire reinforcement, and other inserts are adequately anchored in the
concrete, and that the erection connecting plate or bar yields.
In certain situations where member depth is limited, inserts
are located close to concrete member edges, to each other, or
a combination of these, concrete failures may precede insert
material failure. In such cases, consideration should be given
to the feasibility of attaching connection inserts to member
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DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
reinforcement or providing supplementary reinforcing steel
for confinement. Connection failures resulting from failure
of concrete are typically brittle and, as a general rule, should
be avoided.
6.3—Volume change accommodation
Restraint of strains caused by creep, shrinkage, and
temperature change can cause large stresses in precast
concrete members and their connections. Much of the strain
associated with member creep and shrinkage typically takes
place before making the final connection of precast concrete
members. Strains caused by temperature change, however,
can be particularly damaging in exposed structures, such
as parking structures. The effects of these strains should be
considered in design. The connection should allow movement to take place to relieve the strain. In members particularly susceptible to sun effect, such as spandrels, bolted
connections to supporting columns have been very effective
(Fig. 6.3). This connection allows expansion and contraction of the spandrel through tolerance in the oversized sleeve
through the column.
6.4—Durability
Plates exposed on the surface of precast units, particularly
in parking decks where deicing salts are used, should be
protected by coatings such as epoxy, zinc-enriched paints, or
galvanizing. Stainless steel plates may also be used in severe
corrosive environments. One example of exposed plates
is flange-to-flange connections in pretopped double-tee
systems. Care should be taken when galvanized assemblies
are used in conjunction with mild steel reinforcement. When
assemblies are galvanized, strict adherence to ASTM A153/
A153M will avoid possible strain and hydrogen embrittlement. The concrete surrounding the embed in precast
members is typically of the same durable, high quality as
the member with a minimum strength of the same 5000 psi
(35 MPa) and a water-cementitious material ratio (w/cm) of
0.40 or less.
6.5—Fire resistance
Connections that jeopardize the structure’s stability if
weakened by fire should be protected to the same degree as
required for each of the members they connect.
6.6—Constructibility
Design considerations for connections include:
a) Standardizing products or connections
b) Avoiding reinforcement and hardware congestion
c) Checking material and size availability
d) Avoiding penetration of forms, where possible
e) Reducing post-stripping work
f) Being aware of material sizes and limitations
g) Considering clearances and tolerances
h) Avoiding nonstandard production and erection tolerances
i) Using standard hardware items and as few sizes as
possible
j) Using repetitive details
k) Planning for the shortest possible hoist hook-up time
11
l) Providing for field adjustment
m) Providing accessibility
n) Using connections that are not susceptible to damage
in handling
o) Preventing the pad from walking out of the connection
where design is dependent on shims or pads to transfer loads
p) Accounting for available hoisting and shipping equipment capacity when sizing members and determining joint
locations
q) Performing inspections to insure a good quality control
and quality assurance
r) Personnel safety
6.7—Aesthetics
The final appearance should be considered in the design.
When considering production practices and erection
methods, incorporate a visually pleasing final product.
6.8—Seismic requirements
Connections located in regions of the structure where large,
inelastic displacements will develop during a seismic event
are classified as seismic connections. Seismic design procedures assume energy dissipation by the formation of plastic
mechanisms. When mechanisms occur at joints connected by
seismic connections, energy is dissipated through inelastic
deformations of connections. The seismic design of connections may be necessary in regions of low seismic intensity
because the large mass of concrete structures combined with
poor soils can generate significant lateral forces. Proper
design of seismic connections is required to ensure the
satisfactory performance of commonly used seismic-loadresisting systems.
6.9—Tolerances
Tolerances are specified to permit acceptable deviations
in the dimensions of products during their fabrication and
installation considering economical and practical production, erection, and interfacing aspects. The designer should
realize that normal fabrication, erection, and interfacing
tolerance preclude the possibility of a perfect fit in the field.
The connection should satisfy structural integrity concerns
considering the specified tolerances.
6.10—Vertical connections
Narrow vertical wall panels can be connected rigidly to
create a single wall if connected by ductile connections.
Where the wall panels are linked with ductile connections,
the connections should be able to withstand extreme deformation. Several types of connections have been tested; the
X weld plate and the U weld plate (Fig. 6.10) have been the
most successful. The U plate was used in the PRESSS test
(Priestley et al. 1999) and withstood the extreme drift and
deformation that resulted from forces associated with the
equivalent to 1-1/2 times a Zone 4 earthquake (Fig. 5.1b).
The embedded anchor should be oversized, thereby causing
all deformations to occur in the connecting plate that creates
the connection between the panels.
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DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
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Fig. 6.3—Bolted connection.
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13
shrinkage, creep, or loading. If this can affect stability, attention should be given to detailing the welded members. As a
solution, alternate ends of alternate tees should be welded if
the ends have to be welded to the support.
CHAPTER 8—WELDING CONSIDERATIONS
Fig. 6.10—Deformable connection used in PRESSS research.
Uplates deform as connection accepts load.
8.1—Steel assemblies
Welded connections are structurally efficient and easily
adjust to varying field conditions. The strength of a welded
connection depends on reliable workmanship and the
compatibility of welding materials to the metals to be joined.
As in all assemblies, welding in temperatures below 32°F
(0°C) may require heating of materials to be joined because
of the possibility of fractured welds. Surfaces to be welded,
and surfaces adjacent to a weld, should be uniform and
free from fins, tears, cracks, loose or thick scale, slag, rust,
moisture, grease, paint, or other foreign material that would
prevent proper welding or produce objectionable fumes.
When reinforcing steel is welded to structural steel
members, the project specification for structural steel should
apply. When joining different grades of steel, the filler metal
should be selected for the lower-strength base metal.
CHAPTER 7—ERECTION CONSIDERATIONS
Erection procedures should be considered by consultation with the erector when precast concrete connections are
designed. If more than one connection detail satisfies structural requirements, the selected detail should be one that
expedites both production and erection. Details best suited for
erection may require compromise of some production considerations. If possible, the same connection methods and materials should be used throughout the project. As an example,
if some spandrels are bolted to the columns, all spandrels
should be bolted—both load-bearing and non-load-bearing—
with the same size bolt. The number of different sizes of field
connection hardware, standardize plate sizes, weld sizes, and
bolt sizes should be as small as possible. Connections should
be designed so that a member can be unhooked from the crane
in the shortest amount of time.
The following erection items should be considered when
designing connections:
a) Planning for the shortest possible hoist hook-up time
b) Providing for field adjustment
c) Providing accessibility
d) Using connections that are not susceptible to damage
from handling
e) Identifying proper design, location, use, and restraint
of shims
f) Determining when to shim and when to dry-pack
g) Avoiding unbalanced loading due to loading on one
side of member if possible
h) Determining temporary bracing/erection stability
i) Identifying location of welds
j) Considering hoisting equipment capability and capacity
when determining the connection location
Practice has shown that when member bearing plates
are welded to supports, excess stresses can build up due to
8.2—Galvanized steel
Galvanized metal is a material requiring proper surface
treatment of the connecting plates prior to welding. One
of the three following methods should be used for welding
galvanized steel.
8.2.1 Welding with zinc coating removed—When galvanizing on mating surfaces should be removed, AWS D1.1/
D1.1M and D1.4/D1.4M should be used. The zinc should be
removed at least 2 to 4 in. (50 to 100 mm) from either side of
the intended weld zone and on both sides of the work piece,
if possible.
When galvanized steel is welded, some of the zinc is volatilized on each side of the weld and while a thin layer of
zinc-iron alloy remains, there is a loss in corrosion resistance. In the cases of zinc-rich painted steel, welding causes
decomposition of the paint film, which is burnt off for some
distance on each side of the weld. The width of the damaged
zone will depend on the heat input and preheat.
Removing zinc at the weld location is the most conservative approach in welding galvanized steel. Welding procedures will then be the same as for uncoated steel. Zinc can
be removed by burning with a carbon arc or an acetylene
torch while using an oxidizing flame, by shot blasting with
portable equipment, or by grinding with silicone carbide
abrasive disks. Replace the zinc in the removed region with
a zinc-rich coating after welding is completed.
8.2.2 Welding with zinc coating intact—It is possible to
leave the galvanized coating and weld using galvanized base
metal with the thickest coating anticipated and qualified by
test in accordance with AWS D1.1/D1.1M or D1.4/D1.4M.
AWS D1.1/D1.1M and D1.4/D1.4M permits welding over
surfaces with coatings equal to or less than the zinc-rich
paints. There are zinc-rich paints specially formulated to
eliminate the need to remove the coating from the weld path
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DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
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before welding. A letter should be obtained from the coating
manufacturer stating it is weldable. Porosity may occur in
certain weld joint designs in galvanized steel, depending
on coating thickness, due to volatilization of the zinc in the
coating and entrapment of gas in the weld. This type of joint
with coatings affects porosity because gasses cannot readily
escape from tee joints or from butt joints in thick materials. In
the case of tee or butt joints, a “V” edge preparation or a gap
between the plates allows the gasses to escape and minimizes
porosity. Pore formation is also influenced by the thickness of
the galvanized coating relative to the base material.
8.2.3 Welding galvanized steel—In general, manual metal
arc welding procedures for galvanized steel are similar to
those for welding uncoated steel. Welding of galvanized
steel requires that the welder receive specialized training. In
addition to the added qualifications of the welder and the
welding procedure itself, using the thickest coating anticipated is strongly recommended.
In either case, the weld areas should be given a coat of
zinc-rich paint (95 percent) or epoxy paint immediately
after welding and chipping off the slag to replace the
galvanizing that was removed earlier. Hardware should be
properly cleaned before applying a protective treatment.
Paint all weld areas on primed, exposed, or accessible steel
anchorage devices with a rust-inhibitive primer. Care should
be taken when welding in the vicinity of a bearing pad to
avoid damage to the pad.
Welding electrodes EXX10 and EXX11S should be
applied slower than usual with a whipping action that moves
the electrodes forward 1/8 to 5/16 in. (3 to 8 mm) along the
seam in the direction of progression and then back into the
molten pool. All volatilization of the galvanized coating
should be complete before the bead progresses. This will
prevent zinc entrapment in the weld metal.
A short arc length is recommended for welding in all positions to give better control of the weld pool and to prevent
either intermittent excess penetration or undercutting.
Slightly wider gaps, up to 3/32 in. (2 mm), are required
in butt joints or a 15-degree angle on the edge of a standing
plate for complete penetration. A gap also allows the zinc
and its gases to escape, and reduces cracking caused by
restraint as the weld thickness increases.
Avoid weaving and multiple weld beads. Heat input
into the joint should be kept to a minimum to avoid undue
damage to the adjacent coating.
When welding galvanized steel, hydrogen-induced
cracking of the heat-affected zone may occur in the base
plate adjacent to the weld. Cracking can be avoided by
using precautionary measures such as reducing the cooling
rate of the joint, preheating, or using large-diameter electrodes at high currents. The hydrogen content of a weld can
be increased when it is deposited on galvanized or zincrich primed steel. This extra hydrogen originates from the
pickling process in galvanizing, or from the decomposition
products of primers. It may be necessary to either remove
primers from the vicinity of the joint before welding or
use a higher preheating temperature than would be used on
uncoated steel.
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8.3—Stainless steel
The general procedure for welding low-carbon steels
should be followed when welding stainless steel plates to
other stainless steel plates or to low-carbon steel, bearing in
mind the differences in stainless steel characteristics, such
as higher thermal expansion and lower thermal conductivity.
Stainless steel welding should be done by qualified welders
familiar with the weld requirements of these alloys. Austenitic stainless steels are best welded without preheat, except
to reduce shrinkage stresses on sections over 1-1/4 in. (30
mm) thick or on restrained joints. Because preheat, interpass
temperature below 350°F (177°C), or stinger-bead technique
will reduce the time the heat-effected zone is in the sensitizing range (800 to 1400°F [427 to 760°C]), the amount of
carbon precipitation and warpage are reduced. Preheating is
necessary when carbon steel is welded or the temperature of
the components to be welded is less than 32°F (0°C).
Stainless welds are not as penetrating as those in carbon
steels and the weld metal is slightly more sluggish leaving
the weld rod. Joints in stainless welds need to be more open
to obtain penetration and fusion.
For vertical and overhead welding positions, electrodes
should be 5/32 in. (4 mm) in diameter or less. For vertical
welds on a 3/16 in. (5 mm) (or less) thick plate, make the
weld vertically down using small beads; on thicker plates,
the triangular weave technique should be used while welding
vertically upward.
With relatively high coefficient of thermal expansion
and lower thermal conductivity of austenitic stainless steel,
take precautions to avoid weld bead cracking, minimize the
distortion of steel, and avoid cracking of the concrete.
The following guidelines should be followed to minimize
these problems:
a) Lower the weld current consistent with sufficient penetration to reduce the heat input to the work
b) Use skip-weld techniques to minimize heat concentration
c) Apply other cooling techniques to dissipate heat
d) Use tack welding to hold the parts in alignment during
welding
e) Vary the sequence of welding
f) Keep edges free from adjacent concrete to allow for
expansion during welding when stainless steel connection
plates are used
8.4—Reinforcement
When welding of reinforcement is used to make a connection, weldability characteristics of the reinforcement should
be considered especially for ASTM A615/A615M reinforcing
bars (Rodriguez and Rodriguez 2006). Minimum preheating
and interpass temperatures for welding reinforcing bars,
when required, should consider the highest carbon equivalent number of the base metal. A chemical analysis establishes the weldability of reinforcing bars. The results of the
analysis determine the applicable welding procedures and
preheat and interpass temperature requirements. Striking an
arc outside of the weld area of the reinforcing bar should
be avoided. One practical method of preheating reinforcing
bar and insert plates is to use an oscillating torch while
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measuring preheat with a temperature level or heat-sensitive
chalk. By using the torch, a localized preheated area can be
obtained. This will simplify the welding process. The entire
plate or bar does not need to be heated. Heat-sensitive chalk
is designed to change color or melt when the desired temperature is reached (Soudki et al. 1995).
If preheating is required, heat the reinforcing bar until the
cross section of the bar is at or above the minimum temperature for at least 6 in. (150 mm) at the intended weld location.
As is typical for all welded surfaces, surfaces of reinforcing
bars to be welded and surfaces adjacent to welds should be
free from loose or thick scale, slag, rust, moisture, grease,
epoxy coating, or other foreign material that would prevent
proper welding or produce objectionable fumes. Mill scale
that withstands vigorous wire brushing, a thin rust-inhibitive
coating, or anti-spatter compound, may remain. Shape the
ends of reinforcing bars in direct butt joints to form the weld
groove by oxygen cutting, air carbon arc cutting, sawing,
or other mechanical means. Bars for direct butt joints that
have sheared ends should be trimmed back beyond the area
deformed by shearing.
Welding galvanized reinforcing bars without prior removal
of the coating should be performed in accordance with AWS
D1.4/D1.4M. Welding of galvanized metal may also be done
after all coating is removed from within 2 in. (50 mm) of the
weld joint. Remove the galvanized coating with oxyfuel gas
flame, abrasive shot blasting, or other suitable means.
8.5—Welding practices for epoxy-coated material
When welding or preheating an epoxy-coated base material, remove the epoxy coating from the surfaces to be
heated. After welding, apply a suitable protective coating of
zinc-rich or epoxy paint to the finished joint to restore the
corrosion-resistance properties of the coated bars.
CHAPTER 9—GROUTING
Field-placed grout is used in both tension and compression
connections to fill horizontal and vertical spaces between
members, protect connections, and provide the load-transfer
material in reinforcing bar splice sleeves and dowels.
Proprietary grouts are frequently required in proprietary
connection devices. In typical compression connections, the
grout exceeds the strength of the supporting members by a
minimum of 1000 psi (7 MPa). Grout should be subject to
quality-control testing to ensure that adequate strength can
be attained.
Precast wall panels are often erected by stacking on shims
placed to align and level the assembly. The resulting joints are
subsequently grouted. Place the grout in the joint as soon as
practical after the panel is erected, ensuring that subsequent
loads do not overstress the bearing under the shims and the
load is distributed over the intended joint. Precast columns
are also erected with a grouted joint base. Complete the
connection between anchor bolts and shims before grouting,
and grout the column base as soon as possible because the
anchor bolts and shims are usually not suitable to take the
full column dead load without distress in the supporting pier.
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The maximum erection progress before grouting should be
established as part of the erection procedure.
Most grouting is gravity placed. When grout is pumped
into a sleeve or cavity, however, pump it from the bottom
until grout escapes from a port at the top of the sleeve. In
some instances where increased performance is necessary,
such as in hybrid frames, fibers are added to the grout to
toughen the joint and improve performance. Shrinkage of
grout as it cures can be detrimental to the performance of
the joint. Shrinkage can be compensated for by the use of
commercially available, nonshrink, premixed grout.
CHAPTER 10—REFERENCES
Committee documents are listed first by document number
and year of publication followed by authored documents
listed alphabetically.
American Concrete Institute
ACI 117-10—Specification for Tolerances for Concrete
Construction and Materials (ACI 117-10) and Commentary
ACI 318-11—Building Code Requirements for Structural
Concrete (ACI 318-11) and Commentary
ACI 374.1-05—Acceptance Criteria for Moment Frames
Based on Structural Testing and Commentary
ACI 550.1R-09—Guide to Emulating Cast-in-Place
Detailing for Seismic Design of Precast Concrete Structures
ACI 544.1R-96—Report on Fiber Reinforced Concrete
(Reapproved 2009)
ACI ITG-5.1-07—Acceptance Criteria for Special
Unbonded Post-Tensioned Precast Structural Walls Based
on Validation Testing
ACI ITG-7-09—Specification for Tolerances for Precast
Concrete
ACI T1.2/T1.2R-03—Special Hybrid Moment Frames
Composed of Discretely Jointed Precast and Post-Tensioned
Concrete Members
American Institute of Steel Construction
AISC 325-05—Steel Construction Manual
American Society of Civil Engineers
ASCE/SEI 7-05—Minimum Design Loads for Buildings
and Other Structures
American Welding Society
D1.1/D1.1M:2010—Structural Welding Code—Steel
D1.4/D1.4M:2005—Structural Welding Code—Reinforcing Steel
ASTM International
ASTM A153/A153M-09—Standard Specification for
Zinc Coating (Hot-Dip) on Iron and Steel Hardware
ASTM A615/A615M-12—Standard Specification for
Deformed and Plain Carbon-Steel Bars for Concrete
Reinforcement
International Code Council
IBC 2006—International Building Code
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16
DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
Cheok, G. S., and Stone, W. C., 1994, “Performance of 1/3
Scale Model Precast Concrete Beam Column Connection
Subjected to Cyclic Inelastic Loads—Report No. 4,” Report
No. NISTIR 5436, Building and Fire Research Laboratory,
NIST, Gaithersburg, MD, 59 pp.
Iverson, J. K., and Hawkins, N. M., 1994, “Performance of
Structures During the Northridge Earthquake,” PCI Journal,
V. 39, No. 2, pp. 38-55.
Park, R., and Paulay, T., 1975, Reinforced Concrete Structures, John Wiley and Sons, Inc., New York, 792 pp.
PCI, 2008, Connections Manual MNL-138-08—For
Precast and Prestressed Concrete Construction, Precast/
Prestressed Concrete Institute, 449 pp.
PCI Committee on Connection Detail, 1995, addendum
to “Design and Typical Details of Connections for Precast/
Prestressed Concrete,” PCI Journal, Sept.-Oct., pp. 46-57.
PCI Committee on Connection Detail, 1998, “Standard
Precast Connections—PCI Committee on Connection
Details,” PCI Journal, V. 43, No. 3, July-Aug., pp. 42-58.
Priestley, M. J. N.; Sritharan, S.; Conley, J. R.; and
Pampanin, S., 1999, “Preliminary Results and Conclu-
sions from the PRESSS Five-Story Precast Concrete Test
Building,” PCI Journal, V. 44, No. 6, Nov.-Dec., pp. 42-67.
Rodriguez, M. E., and Rodriguez, A., 2006, “Welding of
Rebars in Reinforced Concrete Structures in Seismic Zones
of Mexico Must be Avoided,” Revista de Ingenieria Sismica,
Sociedad Mexicana de Ingenieria Sismica, V. 75, pp. 69-95.
Schoettler, M. J.; Belleri, A.; Zhang, D.; Restrepo, J. L.;
and Fleischman, R. B., 2008, “Preliminary Results of the
Shake-Table Testing for the Development of a Diaphragm
Seismic Design Methodology,” PCI Journal, Winter, pp.
100-124.
Soudki, K.; Rizkalla, S.; and LeBlanc, B., 1995, “Horizontal Connections for Precast Concrete Shear Walls
Subjected to Cyclic Deformations—Part I; Mild Steel
Connections,” PCI Journal, V. 40, No. 3, pp. 78-96.
Stanton, J. F.; Anderson, R. G.; Dolan, C. W.; and
McCleary, D. E., 1986, “Moment Resistant Connections and
Simple Connections: A Summary of PCISFRAD Projects 1
and 4,” PCI Journal, V. 32, No. 2, Mar.-Apr., pp. 62-74.
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American Concrete Institute®
As ACI begins its second century of advancing concrete knowledge, its original chartered purpose
remains “to provide a comradeship in finding the best ways to do concrete work of all kinds and in
spreading knowledge.” In keeping with this purpose, ACI supports the following activities:
· Technical committees that produce consensus reports, guides, specifications, and codes.
· Spring and fall conventions to facilitate the work of its committees.
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Advancing concrete knowledge
· Educational seminars that disseminate reliable information on concrete.
· Certification programs for personnel employed within the concrete industry.
· Student programs such as scholarships, internships, and competitions.
· Sponsoring and co-sponsoring international conferences and symposia.
· Formal coordination with several international concrete related societies.
· Periodicals: the ACI Structural Journal and the ACI Materials Journal, and Concrete International.
Benefits of membership include a subscription to Concrete International and to an ACI Journal. ACI
members receive discounts of up to 40% on all ACI products and services, including documents, seminars
and convention registration fees.
As a member of ACI, you join thousands of practitioners and professionals worldwide who share a
commitment to maintain the highest industry standards for concrete technology, construction, and
practices. In addition, ACI chapters provide opportunities for interaction of professionals and practitioners
at a local level.
American Concrete Institute
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Farmington Hills, MI 48331
U.S.A.
Phone:
248-848-3700
Fax:
248-848-3701
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Design Guide for Connections
in Precast Jointed Systems
The AMERICAN CONCRETE INSTITUTE
was founded in 1904 as a nonprofit membership organization dedicated to public
service and representing the user interest in the field of concrete. ACI gathers
and distributes information on the improvement of design, construction and
maintenance of concrete products and structures. The work of ACI is conducted by
individual ACI members and through volunteer committees composed of both members
and non-members.
The committees, as well as ACI as a whole, operate under a consensus format,
which assures all participants the right to have their views considered. Committee
activities include the development of building codes and specifications; analysis of
research and development results; presentation of construction and repair
techniques; and education.
Individuals interested in the activities of ACI are encouraged to become a member.
There are no educational or employment requirements. ACI’s membership is
composed of engineers, architects, scientists, contractors, educators, and
representatives from a variety of companies and organizations.
Members are encouraged to participate in committee activities that relate to their
specific areas of interest. For more information, contact ACI.
www.concrete.org
American Concrete Institute®
Advancing concrete knowledge
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