THE DEVELOPMENT OF AN ALTERNATIVE BUILDING SYSTEM
BASED ON THE USE OF AN EXISTING STANDARDIZED COMPONENT:
PRECAST, PRESTRESSED, HOLLOW-CORE CONCRETE SLAB
by
LASZLO SIMOVIC
Bachelor of Architecture,
Institute of Technology
Illinois
(1982)
SUBMITTED TO THE DEPARTMENT OF ARCHITECTURE
IN PARTIAL FULFILLMENT FOR THE REQUIREMENTS
FOR THE DEGREE OF
MASTER OF SCIENCE
IN ARCHITECTURE
STUDIES
at the
MASSACHUSETTS
INSTITUTE OF TECHNOLOGY
June,
©
1984
Laszlo Simovic,
1984
The author hereby grants to M.I.T. permission to reproduce and
to distribute publicly copies of this thesis document in whole
or in pert.
//
-
n
(i
Signature of Author
aszlo Simovic
epartment of Architecture
May 11, 1984
-.
Certified
by...........
.......
. L
- ; . * 3- Waclaw Zalewski
Professor of Structures
Thesis Supervisor
--
Accepted by
N. John Habraken, Chairman
Commitee for Graduate Students
Departmental
MA 5SSACHiUS3ETTT'S
INS~ITUTE
OF TECHNOLOGY
JUN 19 1984
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THE DEVELOPMENT OF AN ALTERNATIVE BUILDING SYSTEM
BASED ON THE USE OF AN EXISTING STANDARDIZED COMPONENT:
PRECAST, PRESTRESSED, HOLLOW-CORE CONCRETE SLAB
by
LASZLO
SIMOVIC
Submitted to the Department of Architecture,
Massachusetts Institute of Technolog y, on May 11, 1984,
in partial fulfillment of the requ irements for the
Master of Science in Architecture Studies degree.
ABSTRACT
The
primary
of
scope
implementation for a new
this thesis is
a
conceptual
building systems approach.
This
system is based on a standardized, economically
and widely used prefabricated structural component.
The
type
concrete
in
floor
design
feasible
in question is a precast, prestressed,
hol low-core
slab, extending it s use from its current application
and roof decks to load-bearing wall panels.
The
system incorporates three additional stuctural members in
order
to
perform
autonomously:
continuous
prefabricated
and
bolts
steel
high-strength
beams,
concrete
reinforced
prefabricated reinforced concrete support panels.
Its application, though primarily directed towards
industry,
can
be utilized in the commercial
and
areas as well.
the housing
industrial
Thesis Supervisor: Waclaw Zalewski
Title: Professor of Structures
ii
In Commemoration To
My Late Grandmother,
Marija Simovic
lii
ACKNOWLEDGEMENTS
thanks
and foremost, I would like to attribute special
First
love,
their
for
and Michael Simovic,
Eva
parents,
my
to
financial
their
and
my wel'l-being,
for
concerns
constant
support throughout my educational endeavors, and to my younger
my
Michael Jr., for his love and for taking care of
brother,
father in my absence.
an
Sass,
Marton
extend my sincere graditude to
to
I wish
and
guided
influenced,
has
close friend, who
and
architect
taught me everything I know in the architectural profession to
and
interests
perspective
my
broadening
ultimately
date;
goals.
to thank Magda Sass,
also
ike
I
would
her
for
and
support,
mora
interests,
perpetual l y shared with me.
for
h er
k indne ss
enduring
has
she
a c lose friend, who gave
I
wish to acknowledge Vaso Bera,
have
becomming an architect and to whom I
of
idea
the
great merr iments in sharing wonderful memories.
I
would I ike to thank all my colleagues at M.I. T.
of
source
constant
and
for
their
friendship
architecture.
in
studies
graduate
through my
me
had
and Harvard
inspiration
devoted professor at l.l.T., Erdman
I must ack nowledge a truly
my min d, induced me to "think" and
"penetrated"
who
Schmocker,
to critica Ily analyze my work with a relentless eye.
wit
I wish to thank Reinhard Goethert alias "Shrimp" for his
and humor in making the learning process "a piece of cake" and
thoughts
his assistance in organizing the contents of my
for
in a cohesive hierarchy.
Wac Iaw
Professor
advisor,
least, to my
the
not
but
Last
il
liant
br
his
with
me
inspired
and
has shared
who
Zalewski,
left
a
undoubtedly
has
mind
remarkable
whose
and
ideas,
me.
on
lasting impression
iv
TABLE OF CONTENTS
ABSTRACT.
..............................................
ii
ACKNOWLEDGEMENTS.........................................iv
1.0
1.1
1.2
1.3
INTRODUCTION................................ Standardized Prestressed Concrete Components .
Manufacturers of Prestressed Concrete Slabs..
Definition of Prestressed Concrete...
2.0
2.1
2.2
2.3
2.4
2.5
REQUIRED STRUCTURAL COMPONENTS.
Prestressed ConcreteSlab.......
Prestressed Concrete Wall Panel
Reinforced Concrete Beam.......
Reinforced Concrete Support Pan
High-Strength Steel Bolts......
3.0
3.1
3.2
3.3
3.4
3.5
DETAILED CONSIDERAT IONS.. .
.
Foundation Details.
.0
Wall Details.......
.
Roof Details.......
.
Typical Sections...
Optional Structural Detai l s
4 .0
4 .1
4 .2
SEQUENCE OF ERECTION..Assembly Method #1....
Assembly Method #2....
5 .0
5 .1
5 .2
FINISHES..................
Interior..................
Exterior..................
6 .0
6 .1
6 .2
6 .3
6 .4
6 .5
DESIGN CONSIDERATIONS.....
Modules...................
Spans/Heights.............
Design Restrictions.......
Exterior Fennestrations...
Applications..............
7 0
7 1
7 2
ECONOMICS OF SYSTEM.......
The Attributes of Precast, Prestressed
Economics of This System.. ............
8.0
EVALUATION
.6
-..
..
. .
.
.
.
.
.
.
.
.
.
1
2
6
7
.10
.11
.11
.15
.18
.20
.23
.24
.29
.37
.41
.49
.
.
.
.
.
.
.54
.55
.61
.73
.74
.78
.
.
.
.
.
Concrete.
& CONCLUSION......................... .....
.....
a
APPEND IX..................
.....
0
Milestones of Prestressed Concrete
Properties Peculiar to Pre stressed Co n cre t e.
..... 0
Materials of Concrete.....
... ..... 0
Tendons...................
..
...
..... 0
Acoustical Properties.....
...
..... 0
Thermal Properties........
.84
.85
.86
.87
.87
.88
. 98
. 98
1 00
102
04
05
09
11
15
18
27
v
Fire Resistance.........................................136
Coordination with Mechanical, Electrical and Other
Substems.............................................140
Structural Fasteners..................................
Bibliography.........................................151
vi
1.0
INTRODUCTION
I
the 1950's, when prestressed concrete was introduced in
Since
the United States, its milieu had developed into what is now a
architectonical
of
and accepted method
acknowledged
widely
is
in the building industry. Its greatest asset
construction
applications.
feasible
economically
the
to
contributed
virtually
been
have
attributions
concrete's
Prestressed
residential,
in:
projects
encompassing
limitless,
Its
applications.
and industrial
commercial
institutional,
and
versatile
be
to
proven
equally
been
has
relevance to scale
flexible.
1.1
STANDARD PRESTRESSED CONCRETE COMPONENTS
concrete
prestressed
standardized
of
varieties
are
There
Each
market.
today's
in
produced
mass
are
that
components
applications
design
specific
pertains
member
corresponding
section
following
The
limitations.
apparent
with
along
an inventory of prestressed concrete components with
presents
brief overviews of prescribed applications and limitations.
1.1.1
Double Tees
a
with
are a basic floor and roof panel member
tees
Double
long
for
excellent
are
They
feet.
80
of
range
span
cantilevers. Designed to simplify and speed erection of single
and multi-story structures. Double tees create a unique effect
when used vertically as exterior wall panels.
b-rn13L
1.1.2 Single Tees
in
are used for floor and roof structural decks
tees
Single
Ily
heavy
ranging up to 120 feet, or for especia
span
longer
each
Normally 8, 10 and 12 feet w ide,
requirements.
load ing
Single
ge.
covera
quick,
unit
pr ovides large, and consequently
mechanical
where
ceilings,
exposed
for
tees
ar e
popular
cess. When
ac
easy
for
stems
between
channeled
be
can
services
for
s haped
custom
be
can
ends
tee
single
canti lev ered,
architec tural treatment.
2
1.1.3 Hollow-Core Slabs
Hollow-core
slabs
find
major
application
in
residential,
commercial, institutional and industrial structures where flat
ceilings
are desired. The bottom sides acts as the
ceilings;
the top side as the floor of the room above. Hollow-core slabs
provide
an
effective barrier to airborne and impact
sounds,
and their voids can be used to carry mechanical services. They
are generally designed for use in shorter spans up to 40 feet.
1.1.4 Channel
Slabs
Channel
slabs
provide
a very rigid structural
member
with
minimum deflecti on characteristics. T hey are ideal where heavy
and roof loads are encountered in short and medium span
floor
ranges.
rC
1.1.5
7HANNEL
S LA E
JS3S
I-Beams
I-beams
find
application
general ly as a long-span
support
extremely
heavy loads. Available in spans
feet,
I-beams
serve
as
the
main
girder
beam-and-deck-systems.
beam
to
to
100
in
many
3
1.1.6 Box Beams
Box
beams are used primarily
as girders In heavy-load type
large
design,
the
proper
mechanical services.
1.1.7
in bridge construction, and also
structural framing systems. With
various
accommodate
can
voids
Inverted T Beams
tota I structural
and ledger beams reduce
T
beams
Inverted
on
in a building because deck members can be su pported
depth
hollow
They
are generally used with double tees and
ledges.
core slabs for structural framing.
U.';
INVERTED T BEAMS AND
LEDGER BEAMS
1.1.8 Piles and Columns
Piles
are used as foundation supports where poor load-bearing
octagonal
They are available in square or
conditions
exist.
cylindrical
sections,
in
size s from 10 to 24 inc hes; hollow
Precast
diameter.
in
up to 54 inches
piles
are
availab le
columns are integra I component of the precast column-beam-deck
system which makes rapid installation possible.
4
1.1.9 Wall
Panels
multi-story
panels are used for partial, f ull-story, or
Wall
use.
load-bearing
or
wal I
curtain
either
for
heights
sculptured,
plain,
in
le
availab
are
panels
wall
Customized
or exposed aggregate units of almost any size, shape
textured
for
materials
insulation
They
also may include
color.
or
improved thermal characteristics.
1.2 MANUFACTURERS OF PRESTRESSED CONCRETE SLABS
prestressed
of
manufacturers
number of major
are
a
There
hollow-core concrete slabs throughout the
United States, each
serving
the
same function. They are:
Flexicore,
Spancrete,
Spiroll,
Dynaspan, Dy-Core and Span Deck. Each manufacturer's
product is distinguishable by the different shape of the voids
at
the center of the slabs, the standard widths in which they
are manufactured and the configuration of the profiles.
?iGO.01
Flexicore (1'-4 & 2 -0)
Spancrete (3'-4 & 5 -0)
1.0 .0.0.O.O.O0\
Spirolt
(4'-0)
0.(0.0.0.0.O.0.
Dynaspan (41-0 & 8'-0)
Dy-Core (4'-0)
Span Deck (4'-0 & 8'-0)
6
1.3 DEFINITION OF PRESTRESSED CONCRETE
and
structural
architectural
concrete
is
an
Prestressed
material
of
great
strength. Prestressed
architectural
and
concrete units are given predetermined, engineered
structural
stresses which counteract the stresses that
occur when a unit
is
subjected to loads. This is accomplished by combining
two
strands
and
high
materials:
high
tensile
steel
quality
concrete. There are two methods of prestressing high
strength
tensile steel strands: post-tensioning and pretensioning.
prestressed concrete means that the steel
Post-tensioning
has
gained
concrete
Is placed and
after
the
tensioned
specific strength.
is
a
stretched
high tensile steel strands
are
In
pretensioning,
Concrete
abutements at each end of the casting beds.
between
the
strands.
As
the
is
then
machine
extruded
to encase
the
bonds to the tensioned steel. When
it
sets,
concrete
strands
reaches a specified strength, the tensioned
concrete
released from the abutements. This stresses the concrete,
are
built-in
tensile
putting
it
under compression and creating
strength.
Most commonly used prestressed concrete utilizes pretensioning
to
its adaptibility to mass-production in a plant. This
due
manufacturing operation takes place in an all-weather enclosed
resulting in completely finished prefabricated members
plants
for ready delivery to the job site.
1.3.1
Ordinary Concrete Beam
Even without a load, the ordinary concrete beam must carry
own
considerable weight - which leaves only a portion of
strength available for added loads.
its
its
7
Under
load,
cracks.
the
bottom of the beam
will
develop
hairline
1.3.2 Prestressed Concrete Beam
In
a prestressed concrete beam, before it leaves the plant, a
slight arch is noticeable. Energy is stored in the unit by the
a
high
action
of
the
highly tensioned steel which
places
An
upward
the
lower porti on of the member.
compression
in
force
of
is hereby created which in effect relieves the beam
having to carry its own weight.
The
upward force along the
load applied to the unit.
length of
the beam counteracts the
8
fundamental idea of this thesis was initiated by friction
The
connections -commonly associated with steel connections. It is
used to service load transmission by friction through physical
are
of adjoining surfaces of members after the bolts
contact
connections
Friction-type
below).
fig.
(See
pretensioned.
a higher factor of safety against slip and thus is most
offer
suitable when stress reversal or cyclical loading may occur.
acknowledged
as
slabs,
concrete
hollow-core
Prestressed,
for
primarily
position,
in a horizontal
applied
is
today,
the
extracting
with
eals
d
thesis
roof decks. This
and
floor
existing
and
slabs from its notorious
concrete
prestressed
wall
load-bearing
a new and unconventional one:
to
context
components, and non load-bearing wall pane Is.
Chapter 2.0 deals with the descri ption of prestressed concrete
additional
the
with
along
modif ications,
its
and
slabs
autonomus
an
a.chieve
to
required
components
structural
building-system.
3.0 concentrates on major deta ils/solutions regarding
Chapter
by means of accomplishing structural integrity of
connections
the elements in question.
Chapter 4.0 explains the chronological sequence of assembly of
the structural elements with two examples.
5.0 addresses the selection
Chapter
interior/exterior applications.
of possible
the design periphery
of
explores
6.0
Chapter
accompanied with a typ i cal housing application.
deals wi t h the economical issues of
7.0
Chapter
conventional
in relation to
comparisions
with
systems.
finishes
this
for
system
system
this
construction
Chapter
8.0, a conclusion and future research is drawn, based
anay
Isis of prestressed hol low-core concrete slabs.
on the
9
2.0 REQUIRED STRUCTURAL COMPONENTS
10
The
essential
components
of this system
consists
of
five
slabs,
elements: prestressed hollow core concrete
structural
reinforced
concrete
wall panels,
prefabricated
prestressed
support
reinforced
concrete
concrete
beams,
prefabricated
panels and high-strength steel bolts.
2.1
Prestressed Hollow-Core Concrete
Slab
A typical cross-section of a prestressed concrete slab that is
into either floor or roof decks is shown in Fig.
incorporated
1. The
holes
or
voids
in the slabs
are
there
to
reduce
weight of the concrete at the neutral axis. There
unnecessary
are
number
of thicknesses available pending on the span
and
tendons
the
anticipated service loads. (Note the prestressed
at the bottom of the slab).
2.2 Prestressed Concrete Wall
Panel
Prior
to
alterating
the existing
function
of
prestressed
required
hollow
core concrete slabs, three modifications are
1)
the
standardized elements. See Fig. 1. They are:
to
the
of prestressed tendons at the "top" of the slabs
augmentation
the
the slabs are casted to secure symetrical forces in
when
camber
any
unwarranted
(to
eliminate
tendons
prestressed
effects),
2)
the elimination of two voids near both ends
of
the
slab
to
permi t maxi mum
a
-solid
section
to
create
compressi on
forces
(section
where
prefabricated
beams
is
attached
to member) and 3) holes that are drilled t hrough the
members
(at
the
solid sections) to allow
install ation
and
permanent
positioning of high-strength steel bolts. Holes may
either be drilled at the job site or preferably pre- dri I led at
the
manu facturing plant. The diameter of the holes depends on
on
the
types
incorporated
bolts
that will be
of
p ending
service loads.
2.2.1
Alterred Profile
There
may
be
an optional alteration on the profile
of
the
is
to
shown in Fig. 2. This
elements
concrete
prestressed
insure
a
weather-tight
joint especially
at
the
perimeter
with
form
(varies
standard
doing
so, the
And
in
walls.
manufacturers)
of the concrete dispatch machine would have to
profile.
be
replaced to the new specification of the desired
The
new
form
will
cost
a
considerable
amount,
however,
very
could
on
the amount of members extruded, it
depending
likely
off-set the initial investment. Also, the new
profile
would only be manufactured once.
2.2.2 Solid Prestressed Concrete Wall
Panel
wa II
concrete
prestressed
trade-off if
solid
is
a
There
less
are used versus the hollow core concrete panels:
panels
concrete is required to carry virtual ly the same load (thi nner
11
required
and fewer prestressed tendons are
wall
th ickness),
of
center
the
in
juxtapositioned
they can be idealily
because
the wal I panels. ( see Fig. 2).
Typical Voids
Prestressed Tendons
at Bottom
Onlyr
PRESTRESSED CONCRETE FLOOR SLAB
Eliminate Voids
When Casting.
I
Hole Pre-Drilled for
Structural Steel Bolt
Optional
Hole
for Added Support
Prestressed Tendons
at Top & Bottom
I
.00.
*
.I
S
H_
(N
Io
0
%
PRESTRESSED CONCRETE WALL PANEL
TYPICAL PRESTRESSED CONCRETE COMPONENTS
Fig. 1
12
Hole Pre-drilled for
Structural Steel Bolt
.Prestressed Tendons
at Top & Bottom
Cont. Neoprene Strip
PRESTRESSED CONCRETE WALL PANEL
Modified Profile
Prestressed Tendons Located
Center of Panel
Hole Pre-drilled for
Structural Steel Bolt
Cont. Neoprene S' p
C;J
0
*
Ti
II
II
I I
SOLID PRESTRESSED CONCRETE WALL PANEL
PRESTRESSED CONCRETE WALL PANELS
Fig. 2
13
2.2.3
Exsiting Prestressed Concrete Wall
Panels
concrete
manufacturers have produced a prestressed
Spancrete
load-bearing
wall
panel
system
deriving
from
prestressed
concrete slab production as shown below.
system of panels ascertain exactly the same principal or
This
restriction:
of
this thesis but it has one inherent
concept
they are limited to one-story height intervals.
The decking system bears directly on top of the wall panels at
panels
Interval,
with
the
proceeding wall
each
floor
positioned on top of the decking system aligning directly over
the preceding lower wall panels.
joints
is by exposed reinforcing bars in the
connection
The
creates
is
grouted afterwards. This type of connection
that
the problem of lateral rigidity after a certain height.
It is interesting to note the various profiles designed in the
panels
to
meet certain conditions including an
interlocking
system, butt joints and a mitered corner condition.
MITERED CORNER
A-Max. 45P
14
2.3 Reinforced Concrete Beam
A vital component of this system is the prefabricated concrete
following
performs
the
which
3)
Fig.
in
(shown
beams
functions:
prestressed concrete
1) Provides a temporary bracing for
wall panels at the initial stages of erection.
panels when
2) Aligns prestressed concrete wall
positioned in place.
3) Creates a ledge or bearing support for prestressed
concrete floor slabs.
4) Increases overall lateral rigidity.
The design parameters for
the beams are:
function of anticipated or
1) The sizes of beams vary as a
surface area for the
required
the
and
loads
service
prescribed
appropriate friction connection.
with
2) Holes are to be drilled through the beams to align
with
and
panels
wall
concrete
prestressed
the
in
holes
in
for recessing boltheads and nuts
provided
countersinking
concrete beams. (Grouted afterwards for waterproofing and
the
to prevent loosening of the connection).
with
3) Concrete beams are to be continuous to correspond
may
(Beams
of the total load-bearing wall length.
width
the
in
restrictions
length
to
due
segmented
be
to
have
transportation).
structural
4) The concrete beams may be designed in three
rebars,
ordinary
using
concrete
reinforced
mediums:
steel
tensile
high
prestressed
using
concrete
high-strength
steel
tensile
high
using
concrete
post-tensioned
and
strands,
cables applied and tensioned after beam is postioned in place.
and
segmented,
be
are required to
beams
concrete
the
If
decided
is
the type of structural medium that
on
depending
to
are four connections that are valid in order
there
upon,
are:
They
4.
Fig.
of the beams, shown in
continuity
achieve
steel
implanted
with
connection
welded
connection,
bolt
and
dowels
steel
with
(not shown in dia.), connection
anchors
above.
post-tensioning method as described
2.3.1
Steel
Angle,
may also be used to serve the same
angles
Steel
(see Fig. 3). Listed below are
beam
concrete
the
advantages and disadvantages.
function
as
the
some of
Advantages
Takes up less space.
Readilt available.
Easily concealed for interior finishes.
Compatable with corrigated sheet metal and/or steel
bar
15
joists for decking.
Elimination of follow-up grouting as
beams to conceal boltheads and nuts.
in
the case
of concrete
D isadvantages
Needs Fireproofing.
-Hole Pre-drilled for
Structural Steel Bol-t
STEEL ANGLE
Varies
Hole Pre-drilled for
Structural Steel- Bol-
Countersinking
for Grouting
U)
ci)
PREFABRICATED CONCRETE
L
Cu
Varies
TYPICAL CONTINUOUS STRUCTURAL BEAMS
Fig. 3
16
Grouted Plugs
for Bol ts
Corr idor
/-Steel
0
0
0
DoweI---
U
Reinforced Concrete Beam
Cori-idor
Bolted
(--Support Panel
Beyond4
Prestressed Concrete Beam
Corr idor
4-Conc. Wa I
Beyond -*I
Post-Tensioned Beam
CONNECTION OF PREFABRICATED REINFORCED CONCRETE BEAMS
Fig. 4
17
2.4
Reinforced Concrete
Support Panel
be
to
support panels are required
concrete
The
re inforced
with
requirements
to specification
according
prefabr icated
the
of
application. The height
construction
each
s pecific
vary
may
panel
may vary according to floor heights, thickness
wall
the thickness of the prestressed concrete
on
dependi ng
vary
may
panel
the
of
top
the
at
ledge
panel s,
the
and
See
beam.
concrete
the
of
depth
the height and
to
accordi ng
Fig.
5.
concrete
reinforced
function of the prefabricated
sole
The
continuous
the
for
panel
support
a
literally
is
panel
support
and
tentative
It serves consecutively as a
beams.
concrete
at
member
termination
the
also
is
It
support.
permanent
wall
load-bearing
concrete
the prestressed
of
end
either
system.
system
is very crutial in the economy of the
component
This
for
waiting
no
is
erection in t hat there
during
especially
are
they
until
beams
concrete
to position and hold the
cranes
valuable
and
place which may take up substancial
in
bolted
erection
of
sequence
the
ates
initi
component
this
Also,
time.
is the only member that requ ires temporary bracing at the
and
prestressed
construction until the first series of
of
onset
place
wall panels and floor s labs are positioned in
concrete
and grouted.
positioned
is
panel
suppor t
concrete
reinforced
The
to the bearing wal Is and the concrete beams. It
perpendicular
is also stacked on top of each of her with steel dowels or pins
and grouted for alignment.
there are two, three or four support panels
Normal ly
depending on the length of the load-bearing walls.
required
18
r
Steel Dowel for Alignment &
Placement of Upper Panel0)
00
7
-Width of Conc. Beam
Hole for Temporary
Bolting of
Concrete Beam
-Width of Adjacent
Prestressed Concrete
Wall Panels
-Width of Conc. Beam
4-,
0
C
a)
0.
Width of Adjacent
Prestressed
Concrete Wa
Panels
I
Female Connection for
Support Panel Below
-
TYPICAL'SUPPORT PANEL FOR CONCRETE BEAMS
Fig. 5
19
2.5 High-Strength Steel
Bolts
The
final
structural component; the key element
that
makes
steel
system autonomous, is the high-strength
this
building
bolts.
Its
only function is to fasten the concrete beams
to
the prestressed concrete wall panels to create a friction-type
connection.
Three
types
of
bolts
are
applicable
to
this
system:
steel
hexagon head bolts, hi gh-strength
steel
high-strength
interference-body
bolts,
and the Huckbolt, (manufactured
by
the Huck Bolt Company).
2.5.1
Hexagon Head Bolts
designed
by
basic types of high-strength bolts are
The
two
hexagon-head
heavy
A325
and A490. These bolts are
ASTM
as
(See
Fig.
6
hexagon nuts.
semifinished
used
with
bolts,
carbon
steel
A325
bolts are of heat-treated medium
below).
having an approximate yield strength of 81 to 92 ksi depending
on diameter. A490 bolts are also heat-treated bu t are of alloy
steel
having an approximate yield strength of 1 15 to 130
ksi
nuts
can
be
the
Bolting of
on
diameter.
also
depending
or
with
tightened
either
by
turn-of-the-nut technique
an
impact wrench.
High-Strength
Interference-Body Bolt
High-Strength
Hexagon Head Bolt
Fig.
2.5.2
6
Interference-Body Bolts
bolts
have
a rounded head and raised
that
has
ribs
These
serrati ons around the shank as well as parral lel to the shank.
The act ual diameter of a given size of ribbed bolt i s slightly
larger than the hole into which it is driven. (See F ig. 6). In
driving
a ribbed bolt, the bolt actually cuts into the
edges
and
then
around
producing a relatively tight fit
the
hole
bo Ited
as
mentioned
above. The
is
interference-body
bolt
avai lab le in A325 and A490 characteristics.
20
2.5.3 Huckbolt
A325
and
also meeting ASTM Specifications of
The
Huckbolt,
specific
are cut to exact final length required by its
A490,
position in the design. One end of the bolt has a formed head;
coarse
end is equiped with two concentric annular
other
the
inserted
fine grooves, as shown in Fig. 7. The bolts are
and
of
the
designed holes which have been cased in both
through
the
concrete beams and through the prestressed concrete
wall
bolt
A metal lock colar is Inserted by hand over the
panels.
end
and around the finer annular grooves. A specific hydralic
machine tool then tightly clamps around the courser grooves at
the
end and stresses the bolt to approximately 70 per cent of
is
stress
strength. Just before this point of
its
ultimate
reached,
the tool clamps around the collar, swaging this into
position on the finer grooves, to hold the stress in the bolt.
stress
is
increased
As
soon
as
the
swaging is done, the
to break off the bolt end at a deep grooved section
slightly,
formed in the bolt just in front of the swaged lock collar.
Installation techniques are shown in Fig. 8.
oCob0y1
Fig.
7
21
Fig.
8
2.5.4 Washers
Washers
are
required for any of the bolts
mentioned
above.
They should be oversized to assist transmission of compressive
forces
from the bolts to the concrete beams or steel
angles.
strength
and
structural
also
have sufficient
They
should
applied on both the nut-side and bolt-side.
22
3.0 DETAILED CONSIDERATIONS
23
3.1
Foundation Details
Fig.
9
&
10 are detail connections of wall
panels
to
the
direct
bearing
of
wall.
They
both
deal
with
foundation
of
poured-in-place
wall panels on top
prestressed
concrete
concrete foundation walls with variations of exterior surfaces
or
finishes. The first detail is exposed concrete wall panels
and the second is with an added exterior cladding.
The latter two details (Fig. 11 & 12) involves bearing of wall
thereby
footing,
concrete
on
top of the
dirrectly
panels
eliminating
costly formwork, labor and pouring of transported
concrete - a substantial savings both in time and labor.
Note:
extra precautions should be taken when grouting
joints
particularly
of
all wall members and thourough waterproofing
for basement applications.
24
V
Poured-in-Place Conc. Slab
-
Weld Angle 2"x0'-4
Cast into Panel
Prestressed Concrete
Wall Panels (Exposed)
I
Cont. Weld Plates
Anchored to Fndn Wall
11
r
3" Min
1" Grout, Shim & Caulk
\I-
0
2" Rigid Insulation
Cont. #5 Rebars
at Top & Bottom
(-
Poured-in-Place Conc.
Foundation Wall
TYPICAL CONNECTION OF WALL PANELS TO FOUNDATION WALL
(Exposed Wall Panels)
Fig. 9
25
Poured-in-Place Conc.
Slab
I
Prestressed Concrete
Wall Panels
Weld Angle 2"xO'-4
Cast into Panel
I'-
Cont. Weld Plates
Anchored to Fndn Wall
Exterior Cladding
1" Grout, Shim-& Caulk
1" Max.
a;
Grade
0
2" Rigid Insulation
Cont. #5 Rebars
at Top & Bottom
0
I
(-
Poured-in-Place Conc.
Foundation Wall
TYPICAL CONNECTION OF WALL PANELS TO FOUNDATION WALL
(With Exterior Cladding)
Fig. 10
26
Poured-in-Place Conc. Slab
Prestressed Concrete
Wall Panel (Exposed)
Grade
Provide Waterproofing
2" Rigid Insulation-,
-
Panels Shimmed & Grouted
Cont. Groove in Footing
Furnished to Line & Grade
3" Min.
Concrete Footing
TYPICAL CONNECTION OF WALL PANELS TO FOOTING
(Slab-on-Grade)
Fig. 11
27
Grouted Joint
Concrete Topp
(Optional)
14-Exterior Cladding
1~
/
-
-
mi
m
-
/
/
/
d
.
--- #3 Rebar Grouted
into Keyways
I
-High-Strength
Steel Bolts
-Prestressed Concrete
Floor Slab
Grouted Fill
Cont. Concrete Beam
BASEMENT
Provide Waterproofing
_---#3 Rebar Grouted into
Keyways and/or Voids
in Panels
Cont. Groove in
Footing Furnished
to Line & Grade
Panels Shimmed & Grouted
Concrete Footing
--
TYPICAL CONNECTION OF WALL PANELS TO FOOTING
(With Basement)
Fig. 12
28
3.2 Wall
Details
of
of the fol lowing details are load-bearing connections
All
concrete
prestressed
wall panels with
concrete
prestressed
floor slabs.
pane Is
The
first detail (Fig. 13) dea Is with continuous wall
of
connecti on
the
showing
lengths)
floor
five
to
(two
conti nuous concrete beams with the floor slabs.
panel
wall
non-continuous
detail showing a
a
Fig.
14
is
vertical continuity is achieved.
connections. This is where
a typical plumbing chase detail
is
15
Fig.
water lines and other me chanical par
stacks,
and econom ically withi
feasibly
intergrated
can be achieved without unnecessa ry drilling
slabs
by
simply
eliminating
portions of
between the concrete beams.
soil
how
shows
be
aphenalia can
It
n the system.
through the floor
panels
wall
the
The following four details (Fig. 16, 17, 18 & 19) concentrates
s labs,
addressing
connections w ith floor
wall
exterior
on
alternative exterior and interior finishes. ( Descr ibed in more
detail in Chapter 6.)
29
Prestressed Conc.
Wall Panels
Grouted Joint
Prestressed Conc.
Floor Slabs
#3 Rebar Grouted
into Keyways
Concrete Topping
(Optional)
1" Min.
---
-
minim
m
/
7
/
I-
1/8"x3" Hardboard
Brg. Strip
High-Strength
Steel Bolts
Grout Fill
Cont. Conc. Beam
SECTION
A-A on
Page 91
TYPICAL CONCRETE CONNECTION OF FLOOR SLABS TO LOAD-BEARING
WALL PANELS (CONTINOUS)
Fig. 13
30
Prestressed Conc.
Wall Panels
Grouted Joint
Prestressed Conc.
Floor Slabs
#3 Rebar Grouted
into Keyways
Concrete Topping
(Optional)
m
r.
-own-
m
m
/.
1/8"x3" Hardboard
Brg. Strip
H igh-Strength
Steel Bolts
Grout Fill
Cont. Conc. Beam
SECTION A-A on Page9l
TYPICAL CONCRETE CONNECTION OF FLOOR SLABS TO LOAD-BEARING
WALL PANELS (NON-CONTINUOUS)
Fig. 14
31
Grouted Joint After
Plumbing Installation
-Concrete Topping
(Optional)
-Prestressed Conc.
Floor Slabs
Space for Plumbing
Chase
-Cont. Conc. Beam
(Prestressed Conc.
Wall Panel Beyond
SECTION B-B on Page9l
TYPICAL PLUMBING CHASE
Fig. 15
32
1" Min.
Exposed Prestressed
Conc. Wall Panels
SECT ION C-C on Page 91
TYPICAL CONCRETE CONNECTION OF FLOOR SLABS TO EXPOSED
LOAD-BEARING WALL PANELS (CONTINUOUS)
Fig. 16
33
Metal Studs with
Batt Insul.
Textured Plywood
(Board on Batten,
Beveled Siding,
Tongue & Groove
Planking, etc.)
m
-
-
m
/
-
111'
-Cont. Conc. Beam
Grout Filled
Metal Studs with
Batt Insul.
-Stucco Finish
SECTION C-C on Page 91
OPTIONAL EXTERIOR FINISH
(Wood, Stucco)
Fig. 17
34
Rigid Insul.
Face Brick
------
7--m
-
/ -
-Cont. Conc. Beam
Grout Filled
Concrete Block
-Rigid Insul.
SECTION C-C on Page 91
OPTIONAL EXTERIOR FINISH
(Brick, Concrete Block)
Fig. 18
35
Exposed Prestressed
Conc. Wall Panels
Grout Filled
.Metal Studs With
Batt Insul.
-Gypsum Board Finish
SECTION C-C on Page 91
OPTIONAL EXTERIOR FINISH
(Exposed Concrete)
Fig. 19
36
3.3 Roof
Details
The
first detail (Fig. 20) shows a typical parapet
with an alternative stone or sheet metal coping.
Fig.
21
is a typical
The
following
roof.
condition
roof detail.
detail
(Fig. 22)
shows a typical
cantilevered
37
Alt. Stone Coping
Sheet Metal Coping.
Wood Blocking
3/8"x8" Anchor Bolt
Grouted into Keyway
3" Min.
Wood Cant
Built-up Roofing
over Rigid Insul.- 1
Exterior Cladding
Prestressed Conc.
Wall Panels
Rigid Insul.
#3 Rebar Grouted
into Keyways
Prestressed Conc.
Roof Slabs
1/8"x3" Hardboard
Brg. Strip
High-Strength
Steel Bolts
Grout Filled
Cont. Conc. Beam
TYPICAL PARAPET WALL DETAIL
Fig. 20
38
Built-up Roofing
over Rigid Insul.
Sheet Metal
Gravel Stop
Wood Blocking
3/81"x8"1 Anchor Bolt
Grouted into Keyway
Rigid Insul.
#3 Rebar Grouted
into Keyways
High-Strength
Steel Bolts
Grout Filled
Cont. Conc. Beam
Exterior Cladding
Prestressed Conc.
Wall Panels
TYPICAL ROOF DETAIL
Fig. 21
39
Sheet Metal Fascia-d
High-Strength
Steel Bolts
Grout Filled
Cont. Conc. Beam
-
Exterior Cladding
Prestressed Conc.
Wall Panels
#3 Rebar Grouted
into Keyways
TYPICAL CANTILEVERED ROOF DETAIL
Fig. 22
40
3.4
Typical
Sections
is
a
section
through
the
The
first
detail
(Fig.
23)
prestressed concrete floor slabs with the prestressed concrete
wall panels, continuous concrete beams and bolt connections in
e levation.
The next detail (Fig. 24) is a section through the prestressed
concrete
panels
looking down towards
the
prestressed
wall
concrete
floor slabs and the continuous concrete beams
below
the floor slabs (dotted line).
section
through
the
The
(Fig.
25) is a
following
detail
at
the
concrete
support
panels
and
wall
concrete
ressed
prest
pane I that supports the continuous con crete beam.
f Ioor
is a section through the prestressed concrete
26
Fig.
corr idor
at
the
concrete beams
the
continuous
and
slabs
the
at
and
panel
support
concrete
the
towards
looking
prestressed concrete wall panels.
showing
Fig.
27 is a transverse section through the corr idor
the
prestressed
concrete
floor
slabs,
non
load-bearing
and
the
panels
prefabricated
wall
concrete
prestressed
segmented concrete beam used for lateral support.
corridor
the
also a transverse section through
Fig.
28
is
show i ng the prestressed concrete floor slabs, non load-bearing
wa I I panels using typical concrete beam for lateral support.
Fig.
concrete
wa I I
is a section through the prestressed
29
the
the concrete support panel at the exterior of
panel
and
bu i Id ing.
41
41
Prestressed Concrete Wall Panels Beyond
11
Concrete Topping (Optional)
#3 Rebar Grouted into KEYWAY
prestressed Concrete Floor Slab
Prestressed Tendons
QQ~rJOOQI
lu..
Cont. Concrete Beam
High-Strength Steel Bolts
SECTION
D-D
on
Page 91
SECTION THROUGH FLOOR SLABS
Fig. 23
42
1'
-
m
-
-
Grouted Vert. Keyw ay
Prestressed Conc.
Wall Panel
Prestressed Tendon
Grouted Joint
High-Strength
Steel Bolt
F
-
1
#3 Rebar Grouted
nto Keyway
K
ED
1" Min.
Width of Conc.
Beam (Below Slab)
(-Prestressed Conc.
*
Floor Slab -
DETAIL E on Page 91
SECTION THROUGH LOAD-BEARING WALL PANELS
Fig. 24
43
CORRIDOR
I
LI
I
V
_
Grouted Joint
(-Prestressed Conc.
Floor Slab-)
Cont. Conc.
(Below Slab)
Prestressed Conc.
Wall Panel
(Non Load-Bearing)
)7
o00oDoY.
I
i
I
I
7I
I~
I
I
I
I
I
I
I
I
I
Conc. Support Panel
Grouted Vert. Keyway
Prestressed Conc.
Wall Panel
(Load-Bearing)
Prestressed Tendon
-Grouted Joint
---High-Strength
Steel Bolt
1" Min.
Width of Conc.
Beam (Below Slab)
(-Prestressed Conc.
Floor Slab--k
'
D -TAIL F on Page 91
SECTION THROUGH WALL PANELS AT CORRIDOR
Fig. 25
44
--
1" Min.
i-
'~
Prestressed Conc.
Floor Slab
Grouted Joint
#3 Rebar Grouted
into Keyway
-Conc. Topping
(*Optional)
S- ~
04101
7-
---
/
m
m
\
-
--
m
I,
/
1/8"x3" Hardboard
Brg. Strip
Cont. Conc. Beam
Prestressed Conc.
Wall Panels Beyond
Conc. Support
Panel Beyond
SECTION G-G on Page 91
SECTION THROUGH FLOOR SLABS AT CORRIDOR
26
F ig.
45
CORRIDOR
-
-
]
I
t-
I
_
Prestressed Conc. Wall Panel
Conc. Topping (Optional)
Prefab. Conc. Beam Bracing
(Resting on Top of Cont. Beam Beyond)
Prestressed Conc. Floor Slab
.o.Q.&0000000
_
.
I
I
-I- --1I
1
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
____
'
Butt Joint
Prestressed Conc. Wall Panel Beyond
Post-Tensioned Tendons
Cont. Conc. Beam Beyond
I
A
I
I
I
I
I
SECTION H-H on Page 91
SECTION THROUGH FLOOR SLABS AT CORRIDOR
(Optional Concrete Beam Bracing)
Fig. 27
46
CORRIDOR
-
Prestressed Conc. WalI Panel
Grouted Joint
Conc. Topping (Optional)
Prestressed Conc. Floor Slab
Post-Tensioned Tendons
I
I
I
I
I
I
0o0*000 SooiO.Q00(o
0
1
I
I
I
I
I
Butt JointCont. Conc. Beam Beyond
Intermediary Conc. Beam Bracing
High-Strength Steel Bolt
Prestressed Conc. Wall Panel Beyond
0
SECTION H-H on Page 91
SECTION THROUGH FLOOR SLABS AT CORRIDOR
(Optional Concrete Beam Bracing)
Fig. 28
47
EXTERIOR
Optional Prestressed
Conc. Wall Panel
(Non Load-Bearing)-7
Conc. Support Panel
Grouted Vert. Keyway
- --.
----
Prestres sed Tendon
Grouted Joint
High-Strength
Steel Bo it
1" Min.
Width of Conc.
Beam (Below Slab)
T
Prestres sed Conc.
Floor Sl Bb
Cont. Co nc.
(Below S lab)
Prestres sed Conc.
Wall Pan
(Load-Be aring)
DETA IL J on Page 91
SECTION THROUGH LOAD-BEARING WALL AT EXTERIOR WALL
Fig. 29
43
3.5
Optional
Structural
Members
substituding
Fig.
30
shows an alternative structural medium
reinforced
prestressed
continuous
the
for
a ngles
steel
concrete wall panels.
prestressed
non -conti nuous
shows the connection of
31
Fig.
and
guide
a
as
beams
flange
wide
using
paneIs
concrete
either
the panels with we Ided stee I angles on
of
connection
side.
Fig.
wall
of prestressed
32 shows an exterior condition
panels using structural T's and a steel plate.
final detail
The
concrete beam.
(Fig. 33)
shows an alternative
concrete
prefabricated
Prestressed Conc.
Wall Panel
Grouted Joint
.1
#3 Rebar Grou ted
into Keyway
Prestressed Conc.
Floor Slab
2 1/2" Min.
Concrete Topp ing
(Optional)
7-li
at... -
-
High-Strength
Steel Bolts
1/8"x3" Hardboard
Brg. Strip
Cont.
SECTION
Steel Angle
A-A on Page9l
TYPICAL STEEL CONNECTION OF FLOOR SLABS TO LOAD-BEARING
WALL PANELS (CONT.)
Fig. 30
50
Prestressed Conc.
Wall Panel
Grouted Joint
#3 Rebar Grouted
into Keyway
Prestressed Conc.
Floor Slab
2 1/2" Min.
-
-
-
-
-Concrete Topping
(Optional)
-
/
/
I
-{-
1/8"tx3" Hardboard
Brg. Strip
- Cont. Steel Angle
Welded to Wide Flange
-
Cont. Steel Wide
Flange
NOTE: Provide
Holes for Rebars
SECTION A-A on Page 91
TYPICAL STEEL CONNECTION OF FLOOR SLABS TO LOAD-BEARING
WALL PANELS (NON-CONT.)
Fig. 31
51
Prestressed Conc.
Wall Panel
4F
Exterior Cladding
Prestressed Conc
Floor Slab
#3 Rebar Grouted
into Keyway
2 1/2" Min.
Conc. Topping
(Optional)
'-I
U
-0
Elm
Sq.
Steel Plate
High-Strength
Steel Bolts
Grouted Joint
1/8"1x3" Hardboard
Brg. Strip
Cont. Steel T
with Welded Webs
SECTION C-C on Page9l
TYPICAL STEEL CONNECTION OF FLOOR SLABS TO LOAD-BEARING
WALL PANELS (CONT.) WITH EXTERIOR CLADDING
Fig. 32
52
Exterior Cladding
Prestressed Conc.
Wall Panel
Prestressed Conc
Floor Slab
" min.
Conc. Topping
(Optional)-
----
7-
m
umin~
-p
1~
/
-'I_
Grouted Joint
1/8"x3" Ha
Brg. Strip
High7Strength
Steel Bolts
Cont. Conc. Beam
#3 Rebar Grouted
into Keyway
SECT ION C-C on Page 91
TYPICAL CONCRETE CONNECTION OF FLOOR SLABS TO LOAD-BEARING
WALL PANELS (CONT.) WITH EXTERIOR CLADDING
Fig. 33
53
4.0 SEQUENCE OF ERECTION
54
There
are two methods of assembling the prestressed
concrete
Both
of
which one is more econom i cally feasib le.
components
descriptions of assembly procedures will be described starting
with the initial development.
For
both cases, The assumptions is that the foundation walls,
the footings of the foundation (two options of support for
or
the
prestressed
concrete wall panels) have been
casted
and
sequential
the
have
reached
sufficient strength to proceed
erection process of construction.
4.1
Assembly Method #1
is
appling
the
initial development the
method
This
concept at a rudimentary basis. The method a pparently had some
erection
resulted in revamping the order of
which
drawbacks
member ,
structural
additonal
an
with
and
prefabricted
a
concrete support wall. This is described in more detail in the
second method of assemby.
There
are four procedures or steps
one floor height.
Step
that completes a cycle
or
1
The
setting of prestressed concrete wall panels preferab
hand Iing
high (for
quick,
easy
length
of
one
story
grouted
bracing)
on
top
of the foundation walIs and
for
bracing is
requi red
staggered
format. Temporary
member.
l y at
and
in a
each
55
Step
2
Lifting
of prefabricated concrete beams on either side of the
prestressed
concrete
wall
panels and held
in
place
until
high-strength steel bolts are positioned and bolted. Procedure
are
the same for each load bearing wall. Note: two cranes
is
required simultaneously.
STEP 3
Reinforcing
Placing
of the prestressed concrete floor slabs.
grouted.
are positioned between every keyway a nd
steel
bars
its
bracing may be removed after grout has reached
Temporary
subsequent yield strength.
56
Step 4
Positioning of corresponding prestressed concrete wall panels,
also
in a staggered format to infill initial voids
developed
Height may
at
ground
level and to give additional support.
only
to
desired
lengths
(limitations
vary
according
to
additional
though
restrictions
conventional
transportation
temporary bracing may be required if members are too high).
concrete
wal I
Note:
the
bolts
of the adjacent prestressed
slide
may have to be loosened to allow wall panels to
panels
level
concrete beams. Grouting may proceed at ground
between
between vertical keyways.
Step
5
Same
as step 2
57
Step 6
Same
as step 3
Step 7
Same as step
4
58
Step
8
wall
panels
(non
concrete
prestressed
of
Placement
slots
or
slipped through continous
are
that
load-bearing)
between prestressed concrete fl oor slabs to create a
spacings
sheer wall for lateral rigidity. Grout al I vertical keyways.
of
wall is conviently located on adjacent sides
Note:
sheer
central corridor.
Step ~9
Same as step 2
59
Step
10
Same as
step 3
60
4.2 Assembly Method #2
This is the subsequent method
method.
assembly
preceeding
are: an additional structural
support panels) and
concrete
of erection.
Step
due to some imperfections of the
two
the
The difference between
member (prefabricated continuous
a switch in the sequencial steps
1
The prefabricated concrete support panels are placed on top of
The
braced.
grouted and temporarily
walls,
foundation
the
forthcomming
the
to
perpendicular
placed
are
panels
anticipated
the
of
ends
both
at
panels,
load-bearing
load-bearing walIs and at the shear walIs as shown.
this
in
is a substancial reduction of bracings
there
Note:
procedure.
Step
2
desi gned
the
concrete beam i s hoisted on
prefabricated
The
the
w
panels
( ith
only of the s upport
side
one
on
ledges
into
and
exception of end walls), and bolted through the beams
the panels.
in
cranes are not required and there is a savings
two
Note:
rete
conc
the
s
supporting
panel
the support
having
by
time
the
eliminating valuable ti me consumed by holding
and
beams
method.
assembly
first
the
in
as
beams by the crane
Step
3
a
in
panels
wall
concrete
prestressed
of
placement
The
order on top of the foundation walls (or footings)
sequencial
and grouted. The concrete beam acts as a temporary support for
panels and eventually a permanent connection. The lengths
the
the panels may be of longer lengths and should vary in one
of
the
of
that are staggered at the top ends
increments
story
continues
construction
when
panels to add support and rigidity
in height at the following stages of erection.
wall
concrete
of staggaring the prestressed
need
No
Note:
lengths.
longer
of
panels, and panels are
Step
4
The corresponding concrete beam is placed on the opposite side
of the prestressed concrete wall panels and onto the ledges of
the support panels.
order
sequential
a
may proceed in
procedures
bolting
The
throughout the length of the load-bearing walIs.
Step5
Placing of
prestressed concrete
floor
slabs.
Reinforcing steel
bl
bars
beam
are inserted between every keyway and grouted.
is introduced to give lateral support.
Concrete
are the five procedures or steps that completes a cycle
These
or one floor height.
Step
6
Same as step
2 and 4
Step 7
the
step
of
placing
Same
as
step
5 with the additional
concrete wall panels (non load-bearing) on either
prestressed
side of the central corridor
which acts as a shear wall as in
the previous assembly procedure.
Step
8
Same
as
Step
9
step
2 and
4
Placing of the next series of prestressed concrete wall panels
between the staggered ends of the panels below, and step 4.
Step
10
Same as step
5.
62
~
'N
I
-
'N
K
PROCEDURES OF ASSEMBLY
Step One
Support Panels on Foundation Wall
63
A
A
A
Step Two
Cont. Conc. Beams Bolted to Support Panels
64
0
.C-
'U
0)
C
-~
0
C
L\
Step Four
Cont. Concrete Beams & Bolted
66
0
L
L
E
Go
U)
(D L
C/)
o0
L
00
.0
C,
'.0
A
Step Six
Conc. Support Panels, Conc. Beams & Bolt
68
Step Seven
Conc. Floor Slabs &
Non Load-Bearing Conc.
Wall Panels
69
Step Eight
Conc. Support Panels & Cont. Conc. Beams
70
06
E
co
0
CL
a'-
(U
0
0
Step Ten
Concrete Floor Slabs
72
5.0
FINISHES
73
5.1
INTERIOR FINISHES
5.1.1
Floors
Floor
systems
of
prestressed concrete
slabs
readily
lend
Some
finishes.
themselves
to
virtually any available floor
underlayment
types
of
finishes
of
mastic,
may requ ire an
gypsum concrete or concrete, while others are applied directly
to
the prestressed concrete slabs with only a minimum
amount
concrete
Under layment or
topping
of
surface
leveling.
is
floor
when
a
resilient
covering
is
used.
required
The
should
be
thouroughly
cleaned
slabs
concrete
prestressed
before application of any und erlayment or concrete topping.
of the top surface of the installed deck will
Condition
depending on span, load, openings and other details.
vary
a concrete topping is desired, it can be designed to act
When
structurally with the prestressed concrete slab as a composite
material.
or it can be assumed to act only as a fill
system,
the
topping
of
affect the specification
choice
will
This
material and placement.
5.1.2 Concrete Finishes
When
concrete
is
to be used structurally or
as
a
wearing
psi.
Color
3000
specify a minimum of
surface,
one
should
pigments,
hardeners
or
wearing aids may be
added.
Similar
Where
terrazzo.
prevail
for
cast-in-place
details
should
concrete
slab
align
joints with the prestressed
practical,
joints.
1 1/2" Min. Conc.
Topp ing
Prestressed C
Floor Slab
74
5.1.3 Floor
Coverings on Underlayment
one
should be speci fied similar to the
mate rial
Underlayment
latex
concrete,
haltic
general types: asp
following
of
the
underlayment
of
Thi ckness
underlayment.
mastic
concrete,
construction
off
level
to
enough
only
be
should
irregularities.
used
be
procedures should
and
specifications
S imi tar
bed
which normally require a mortar
f oor ing materials
p lacing, such as cut stone or precast terrazzo.
for
for
Asphalt or Vinyl Tile
or Sheet Floor Covering
Underlayment
Fin.
-
Level
Prestressed Conc.
Floor Slab
5.1.4 Carpeting
sk im
carpeting directly on prestressed concrete slabs, a
For
r
ities
irregula
where
applied
be
should
leveling
coat of mastic
exceed 3/16 in. A minimum of 55 oz. pad should be specif ied.
Carpeting over Pad
Prestressed Conc.
Floor Slab
75
5.1.5
Exposed Ceiling
Slab - Painted
smooth
concrete slabs have an exceptional ly
prestressed
The
vibration
thourough
the
of
because
obtained
surface,
underside
beds.
casting
concrete in steel forms in the
dense
the
of
Nicely rounded corners are built into the individual units.
a paneled ceiling is desired in residential, commerc ia I,
When
hospital or similar applications, simply caulking the
school,
econom ica I
between the slabs and painting is the most
joints
solution.
waterproof
coat should be rubber latex paint or a
prime
The
finish
The
slab.
concrete
other
any
for
desirable
sealer as is
an
or
finish
wal
I
flat
paint,
oil
rubber,
be
may
coat
by
obtained
is
appearance
distintive
A
finish.
emulsified
stippling the final coat.
5.1.6 Other Ceiling Treatment
simply
the most economical ceilings are obtained by
Although
treatments
caulking and painting as outl ined above, additional
can be applied which produces a variety of results.
tiles that are applied directly onto the
Cei Iing
concrete slabs.
prestressed
is
app lied acoustical material when acoustical control
Spray
be
fiber or other acoustical material may
mineral
required,
textured
a
on the slab's surface creating
d irectly
sprayed
finished.
5.1.7 Suspended Ceiling
conventional hung ceilings may be in conjunction with
All
in
slabs by inserting the hangers
concrete
prestressed
joints between slabs before grouting.
also be hung
ceilings
may
Alternative Iy,
grouted, by drilling underside of the cores
the hangers in the cores.
Hangers
dril ling
the
the
are
slabs
after
and then inserting
be installed from the top of the
also
may
through the cores, provided topping will be
the suspended ceiling
of
purpose
Principal
ducts, pipes or other mechanical parapenalias.
is
to
slab
used.
by
conceal
76
Galv. Strap Hanger
Installed Before
Slabs are Grouted
essed Conc.
Slab
Suspended Ceiling
77
5.2 EXTERIOR CLADDING
applied
are a number of possible materials that can be
There
concrete
the facade of the exterior prestressed
to
directly
concrete
continuous
the
directly on
bearing
panels,
wall
wall
the
leave
one may simply choose to
course
Of
beams.
exposed which also presents a wide variety of finishes
panels
and textures.
5.2.1
Brick/Block
system.
concrete block is compatable with this
and/or
Brick
veneer
brick
to
similar
is
methodology
construction
Its
that
is
difference
only
The
34.
Fig.
See
construction.
building
the
of
perifery
the
around
required
is
scaffolding
when laying the brick/block on the facade.
5.2.2 Wood/Stucco
compatible alternative,
and/or stucco finish is another
Wood
construction.
also applied similarly to brick veneer
is
and
See Fig. 35.
5.2.3
Exposed Concrete
as
far
as
the most flexibil ity
provides
concrete
Exposed
be
can
finishes
The
variations.
color
and
finishes
textures,
I
wal
concrete
prestressed
the
when
cases
most
in
applied
reduction.
cost
a
manufactured
are
panels
The interior side of the prestressed concrete wall panel s wil I
Fig.
some sort of insulation: rigid or batt insulation.
need
board
shows metal studs with batt insu lation and a gypsum
36
finish.
patented
a
with
finish can be achieved
exterior
unique
A
the
compacts
and
screeds
process. A revolving roller
Corewall
the
create
to
panels
the
of
surface
top
the
on
concrete
the
varying
By
Fig.37).
(see
effect
architectural
desired
the
to
attached
discs
of
number
a
of
spacing
and
profile
available.
is
finishes
sculptured
of
variety
wide
a
roller,
Fig.
38 gives us a sampling of exterior finishes
achieved by various means.
that can
be
78
Rigid Insul.
Face Brick
-Cont. Conc. Beam
*Grout Filled
Concrete Block
-Rigid Insul.
SECTION C-C on Page 91
OPTIONAL EXTERIOR FINISH
(Brick, Concrete Block)
Fig. 34
79
Metal Studs with
Batt Insul.
Textured Plywood
(Board on Batten,
Beveled Siding,
Tongue & Groove
Planking, etc.)
m
/
*Cont. Conc. Beam
Grout Filled
Metal Studs with
Batt Insul.
Stucco Finish
SECTION C-C on Page 91
OPTIONAL EXTERIOR FINISH
(Wood, Stucco)
Fig. 35
80
-Exposed Prestressed
Conc. Wall Panels
Grout Filled
.Metal Studs With
Batt Insul.
-Gypsum Board Finish
SECTION C-C on Page 91
OPTIONAL EXTERIOR FINISH
(Exposed Concrete)
Fig. 36
02
m
-4
~tJ
Ca
~tA'.'
*~mrrnr:rw::
r ~sjcrkrrcmuch~iaM
"it
,
Will-.'
cv
*
rtznninnita"amn act 1et~r1 ur rw!r
it,.
F
~m ii
~0
V
Exposa AggregCOl - RIDDOO
Exposed Aggregat
Fig.
38
83
6.0 DESIGN CONSIDERATIONS
84
6.1
Modules
mention
manufacturers
concrete
prestressed
the
Among
width
alternate
are
there
introduction,
the
in
previously
dimensions of hollow-core concrete slabs that varies with each
4'-O,
producer. The scope of dimensions are: 1'-4, 2'-0, 3'-4,
5'-0 and 8'-0 widths.
on these dimensions, the designer will need to know the
Based
are
members
concrete
prestressed
where
location
nearest
dimensions
width
standard
the
acknowledge
and
produced
the
as
the manufacturer. This should serve
with
associated
concrete
prestressed
of
system
module
the
for
basis
large
In
incorporated into the design.
members
hollow-core
manufacturers
three
or
two
be
may
there
areas,
metropolitian
a relative close proximity which presents the designer
within
with a more flexible module selection.
an
module sizes plays
to say, the determination of
Needless
and
economy,
regarding two major criterias:
role
important
design flexiblity. The larger the width dimension, i.e. larger
the more economical it becomes simply on the basis of
member,
fewer
with
erection
quicker
and
requirements
labor
less
on
depends
also
project
members. The design flexibility of the
integration
of
the module dimensions because of the imposition
and
economical,
in order to be efficient,
design
the
into
functional.
The ideal module dimension of prestressed concrete elements is
and/or possible comb i nations of 4'-0 widths ( if needbe).
8'-0
the
in
sizes are an architectonic dimens on
of
these
Both
construction industry.
The modules should be aligned both horizontal ly and vertical ly
slabs.
floor
wall panels should correspond to the
the
i.e.
This should prevent any unneccessary cutting of elements. More
is
that
bars
allocation of reinforcing
the
is
important,
to
slabs
concrete
placed in keyways at ends of the prestressed
adjoining floor slabs or wall panels (if exterior walls).
the
wal I
the
accomplish this, the floor slabs and
to
order
In
the
through
penetrate
to
rebars
have to align to allow
panels
wal I panels.
85
6.2 Spans/Heights
Floor
Spans
of
lengths
definite limitation of maximum span
is
a
There
40'.
to
35'
from
ranging
slabs
floor
concrete
prestressed
Considerations should be given to the allowable service loads,
concrete
not
or
ratings and whether
fire
codes,
building
determined.
be used before span dimensions are
will
topping
These considerations wi ll effect the locations of load-bearing
space
and
functions
the
effects
ultimate ly
which
walls,
allocations between the walls.
Wall
Heights
is
lengths for prestressed concrete wall panels
maximum
The
ranges
that
on the allowable transportation limitations
based
the
plus 10" for
If a typical floor height is 8
45'.
around
of
45'
of
length
a
then
(8'-10),
thickness
slab
floor
floors
5
panel will accommodate
wall
concrete
prestressed
An obvious and substantial savings increase in labor
lengths.
and
production
one-time
time with
construction
and
costs
handling of one wall member versus five wall panels associated
with Spancrete's load-bearing prestressed concrete wall system
mentioned in chapter 2.2.4.
heights
is substantially more flexibility with ceiling
There
the
on
Based
system.
wall
precast
other
any
with
than
various
with
panel
wall
concrete
prestressed
continuous
for
that are drilled through the wall panels
holes
lengths,
fluctuate
to
drilled
be
can
beams,
concrete
attachment of
the
8'
floor intervals e.g. one floor height can be
desired
any
floor
proceeding
the
and
height
12'
at
be
can
next
the
high,
implied
additional
any
without
high
10'
be
can
height
prefabricated
costs with the exception of the
constructional
the
to
correspond
to
panel
support
concrete
reinforced
prestressed
the
the waste of materials. Also,
and
heights,
concrete wall panels can come in any desired lengths up to 45'
due to the the production methodology of the members.
86
6.3 Design Restrictions
The
design
restrictions
of this system
confronted
by
the
designer is limited to straight load-bearing walls/party walls
its
on
(depending
width
or
length
the
extends
that
be
must
walls
The
building.
the
of
application)
parallel with each other (for bearing support
juxtapositioned
decking system). Also, the distance between the continuous
of
there
depends on the decking system used and
walls
straight
respective maximum spans.
6.4 Exterior
Fenestrations
As
far as deciding on what type of exterior fenestrations
may want to apply, he or she is only limited to
de signer
or her immagination.
6.4.1
the
his
Perpendicular to Load-bearing Walls
exterior walls that are perpendicular to the load-bearing
The
desired
limitless as far as the type of materials
are
walls
light
the type of wall construction. It can range from a
and
curtain wal I to a solid masonry wal I construction with punched
The curtain wall construction would be secured onto
openings.
the longitudinal edge of the prestressed concrete floor slabs.
At the same time, the masonry wall can be constructed the full
run
or
slabs,
adjacent the floor
building
the
of
height
in
result
would
This
slabs.
floor
the
between
intermittedly
a
of emphasizing contrasting materials with
possibility
the
subdivision of horizontality.
continuous
also be provided by protruding the
can
Balconies
beams and floor slabs beyond the reinforced concrete
concrete
support panels. Cantilevering has certain limitations based on
the
Also,
beams.
concrete
continuous
the
of
design
the
is restricted to extend the length of the cantilever
designer
the full length of the concrete floor slabs unless masonry
to
construction is used.
6.4.2 Parallel
to Load-Bearing Walls
exterior walls running parallel to the load-bearing walls
The
presents more restrictions than walls running perpendicular to
of
The designer must consider the structural integrity
it.
the
system in that there should be a continuity of
wall
the
wall
of
wall panels. A certain amount
concrete
prestressed
panels may be deleted for opennings of windows and/or doors.
wide
material selection on these facades also presents a
The
in
choices, though its applications are limited
of
spectrum
continuous
the
between
that it should be applied
sense
the
concrete beam.
87
Cantilevering
may
also
be
achieved
by
eliminating
the
corrsesponding
wall panels, and by extending the
prestressed
concrete
floor
stabs
(bearing over the
continous
concrete
beams) beyond the exterior wall plane.
6.5 Applications
This
building
system
may be incorporated
building type in the construction industry.
6.5.1
in
virtually
any
Residential
This system
applicable
slabs.
is geared
spans
of
to the housing industry primarily of its
the prestressed concrete floor and
roof
In
apartment building, the central or double- l oaded
corridor
l
.
This
is
to
the
most
economica
is
considered
system
public
understand
when we consider that every square foot of
corridor serves two apartments instead of one.
Each
bui Iding
type has a modifying effect on the
apartments
placed
w ithin its confines. The central corridor type, limits
the
of the apartments minimally. What determines
the
layo ut
is
kind
of apartment layout the designer is able to work out
based on the total building length and depth.
order to be economically feasible the typical floor should
In
contain a maximum number of apartments. Given the minimum room
determined by the program, just so many apartments can
widths
fit
into
the
available
building
length.
The
number
of
apartments in this length can be improved on if each apartment
shorter
is
arranged - keeping the gross area constant - with
will
and increased depth. Naturally, this
exposure
exterior
narrow
on the apartment. Bedrooms become so
put
constraints
the
exterior
and
desks must be placed along
that
dressers
wall,
thus
eliminating
the
option
of
floor-to-ceiling
In
The
inner ends of the rooms become darker.
fenestration.
spite of all this, buildings with narrow, deep apartments tend
to
be more economical: using the same gross square foot area,
they have smaller perimeters and less exterior wall.
one-bedroom,
show
efficiency,
illustrations
The
following
two-bedroom,
and three-bedroom apartments with average
depth
and
depth
as well as with increased
exposure
and
exterior
reduced
exterior exposure. They also show the consequences of
using some of the apartment space ("borrowing") to accommodate
core elements along the central corridor.
It
is important to be aware that the apartments are
reflecting more the marketing conditions than living
averages
styles.
88
6.5.2 Commercial,
Industrial,
&
Institutional
and
industrial
commercial,
in
applications
are
There
on
are certain restrictions based only
There
institutional.
and
spans of the decking systems. In commercial
maximum
the
composed
applications, the perimeter walls may be
industrial
prestressed concrete wall panels while the interior may be
of
to
system
beam
support, e.g. post and
of
means
other
of
obstructions otherwise unavoidable if wall panels are
prevent
used.
89
I
LEGEND
Load-Bearing Prestressed Concrete Wall Panels
Non Load-Bear i ng Prestressed Concrete Wa I I Pane I s
0
NMI
I
I.
IL
Balcony
8'-0 wide
Modules
C
i-
E
C
A
A,
H,
Elev.
H~
G
StaiwellCorridor
4HF
B
B
Prestressed Conc.
Floor Slabs
D
1 1
4'-0 wide
Modules
4D
I
LEGEND
----
Load-Bearing Prestressed Concrete Wall Panels
Non Load-Bearing Prestressed Concrete Wall Panels
LAYOUT OF PRESTRESSED CONCRETE ELEMENTS
'~0
Shaft
j
18'-0
j
L
21'-0
1
F
I
Efficiency Apartment
I
-I
r- _
Efficiency
7
Layout
LEGEND
Load-Bearing Prestressed Concrete Wall Panels
Non Load-Bearing Prestressed Concrete Wall Panels
92
12' -0
A
r
F
16'-0
b-
16/-0
S121-0
F
U
One Bedroom Aartment
*~ 12'-O
lb
.A
________
12/-
~
,
16'-0
Ii
II
II
II
IF
II
II
Ii
II
II
One Bedroom Layout
LEGEND
Load-Bearing Prestressed Concrete Wall Panels
Non Load-Bearing Prestressed Concrete Wall Panels
93
12' -0o
2
12'-0
121-0
-
*
--
-
iwf~
--
16/-0
1'O
-.
-
--
-
-1
--
-
w
i
12'-0
61
F
12'-Q
1 2--Q
.a
F
16/-0
16/-0
F
Two Bedroom Apartment
LEGEND
Load-Bearing Prestressed Concrete Wall Panels
Non Load-Bearing Prestressed Concrete Wall Panels
94
12'-0
12'-0
-L
J
F
II
24 - 0
_______________________________
16'-0
28' -0
-I
_____
__________________________
ii
.1
*1
__________________________
Two Bedroom Layout
LEGEND
Load-Bearing Prestressed Concrete Wall Panels
Non Load-Bearing Prestressed Concrete Wall Panels
95
Three Bedroom Apartment
LEGEND
Load-Bearing Prestressed Concrete Wall Panels
Non Load-Bearing Prestressed Concrete Wall Panels
96
24I-0
r28/-0
24' -0
ti
Three Bedroom Layout
12t-
11.
r
1
-
0
a
I.
2
-
6
-
a
Three Bedroom Apartment
LEGEND
Load-Bearing Prestressed Concrete Wall Panels
Non Load-Bearing Prestressed Concrete Wall Panels
97
7.0 ECONOMICS
OF THE SYSTEM
98
on ly
be
The
use
of precast, prestressed concrete units can
effective
more
economically
be
to
shown
be
justified
if it can
than building with traditional methods.
Section
7.1 addresses the advantages of conventional precast,
concrete that is existing in todays market, while
prestres sed
as
far
deals more directly with this system as
7.2
section
economy is concerned.
7.1
The Attributes of Precast, Prestressed
Concrete
Less Construction Time
Precast, prestressed concrete components can be uniformly mass
and
conditions
manufacturing
controlled
under
produced
of
production
year-round
for
allowing
environments,
at
proceeds
work
foundation
and
excavation
while
components,
Components
schedule.
construction
Compressed
the site. Result:
structure
usually erected directly from the truck to the
are
or
access
for projects with limited site
ideal
it
(making
those with on-site material storage space). Total construction
because
reduced
also
are
costs
labor
on-site
and
time
components fit readily into place.
Improved Construction Efficiency
smaI ler
components,
standardized
With
used, resu It ng
be
can
crews
erection
savings.
Lower
and
in
more
time
efficient
money
and
Interim Financing Costs
major
rates and cost of interim financing are
mortgage
High
conce rns of builders, owners and developers who face potential
a
ob taining
from
construction
during
f inan cial
risks
schedule
and/or
cost
to
mortgage,
or
loan
const ruction
of
precast,
time
construction
reduced
The
overr uns.
financial
these
minimizes
effectively
concrete
prest ressed
risks .
Cost Control
Cost information is monitored from preliminary studies through
and/or
designer
the
a Ilows
which
completion
contract
to
of
start
very
the
from
price
a
reliable
from
developer to work
the anticipated project.
Mortgage
Companies More Receptive
project
lower
are more receptive to the
companies
Mortgage
prestressed
of
precast,
benefits
inherent
the
and
costs
concrete. More accurate predictions of the completion date can
be made due to the reduced construction time.
98A
Early
Enclosure
for Other Construction
the structure can be erected so qui ckly, other trades
Because
the
for
provided
A working platform is
sooner.
start
can
for
need
the
rises, eliminati ng
structure
the
as
trades
scaffolding.
Earlier Occupancy
prestressed
precast,
why
reason
This
bottom-line
is
the
a
are the economical choice. The faster
strustures
concrete
building
is completed, the sooner it can be put to use by its
- and precast, prestressed structures save construction
owner
time.
Energy Efficiency
energy
excepti onal
provides
concrete
prestressed
Precast,
of
use
the life of the building. The
throughout
efficiency
and
heating
concrete provides greater
prestressed
precast,
outside-air
its
to
due
ef ficiency
equipment
cooling
temperature
control,
condensation
protecti on,
infiltration
and thermal storage capabilities.
stability
Earthquake,
Fire Resistance
rel iable
absolutely
concrete provide s
prestressed
Precast,
dependence
total
ithout
fire protection of lives and property w
insurance
reduced
systems, often resulting in
sprinkler
on
in areas
ed
us
widely
are
components
prestressed
rates. Precast,
severe
to
subject
ar
which
California,
and
Alaska
as
such
earthquakes
Lower
Insurance Costs
the properties of fire
on
Based
insurance
concrete,
prestressed
insurance rates to owners.
and
durab.ility
companies
precast,
of
lower
offer
Design Versitility
concrete
prestressed
of precast,
possibilities
design
The
to
applied
been
have
virtually limitless and
are
components
great
the
to
In
addition
of
structure.
form
every
nearly
be
can
components
other
components,
standard
of
variety
and
sizes
shapes,
of
number
infinite
almost
in
custom-made
finishes.
High Durability,
Low Maintenance
under
prestressed concrete components are produced
Precast,
consistently
in
conditions, resulting
factory
high-qua lity
durable products that require minimal. future maintenance.
99
7.2 Economics of
This System
The basic prerequisite for any successful,
systems can be simply stated as:
1)
2)
3)
4)
economical
building
Largest possible elements
Repetitive elements
Minimal or no temporary bracing
Safe, simple, proven connections
This
construction
of
reduces
costs
in
approach
of
type
detai I ing,
and erection. Thes e benefits are
production
most
fully
realized when the systems approach is introduced in the
ear Iy design stage.
Precast,
prestressed
concrete decks reduce cost by
reducing
need
and in certain cases, eliminating the
height,
building
for fireproofing altogether.
The
followi ng
a
cost
precast,
table
is
of
estimation
floors
concrete sl abs for roofs and
prestressed
hol low-core
Data,
Cost
(grouted)
from the Means Building Construction
1984.
CREW
C-J1
SLABS Prestressed roof and floor members, grouted, 4" deep
6" deep
j
8"deep
4
10" deep
12" deep
The
following
table
prestressed
concrete
from the same source.
DAILY
OUTPUT
4,875
5,850
UNIT
SF.
High rise, 4' x 8', 4" thick, smooth gray
Exposed aggregate
8' x 8', 4" thick, smooth gray
Exposed aggregate
20' x 10', 6" thick, smooth gray
Exposed aggregate
30' x 10', 6" thick, smooth gray
White face
.
BARE COSTS
INST.
TOTAL
.51
.43
2.81
2.78
TOTAL
INCL O&P
3.23
3.17
7,200
2.50
.35
2.85
3.22
.8,800
2.75
.28
3.03
3A1
9,500
3.10
.26
3.36
3.77
cost estimation
is a
wall panels for high-rise
I WALL PANELS.
MAT.
2.30
2.35
CREW
DAILY
OUTPUT
C-I1
288
UNIT
S.F.
288
512
512
1,800
1,8002,100
2;100
"
precast,
of
construction
MAT.
6.70
7.25
6.70
7.25
8
8.75
8
9.25
BARE COSTS
INST. I TOTAL
8.35
8.35
4.70
4.70
1.34
1.34
1.15
1.15
15.05
15.60
11.40
11.95
9.34
10.09
9.15
10.40
TOTAL
INCL O&P
18.75
19.35
13.75 14.35
10.60
11.45
10.35
11.75
100
bare costs of precast,
Total
added together equals $18.71,
cost of $3.74 per sq. ft.
prestressed concrete wall panels
divided by 5 gives us an average
and profits, of precast concrete wal I pane Is
overhead
Total
added together equals $21.56, divided by 5 gives us an average
cost of $4.31 per sq. ft.
panels
estimati on of precast concrete wall
cost
For
a
page
previous
the
on
table
see
low-rise construction
deduct 25% for install ation costs.
and profits of precast
overhead
total
The
$101.70, divided by 8 gives us $12.71 per sq.
concrete
ft.
prestressed
costs that of precast,
compare
we
If
and the precast concrete wall panels, we can
slabs
see a substantial difference.
The average cost of mater ial
per sq. ft.
$3.74
is
slab
an
average of
cost
panels
$11 .62
versus
construction
construction.
for
and
equals
concrete
obviously
for precast, prestressed concrete
wall
concrete
while the precast
low-rise
for
$10.68 per sq. ft.
high-rise
for
ft.
sq.
per
precast,
for,
profits
for overhead and
costs
average
The
the
while
ft.
sq.
per
$4.31
is
slab
concrete
prestressed
precast concrete wall panels cost an average of $12. 71 per sq.
for
for low-rise concstruction versus $13.80 per s q. ft.
ft.
high-rise construction.
panels
should be mentioned that the precast concrete wall
It
structural
additional
a curtain wall where an
as
used
are
framing construction (concrete or steel) is required to "hang"
are
slab
panels. Whereas the prestressed concrete
wall
the
the
incorporates
also
but
as an exterior cladding
used
also
walls
load-bearing
or
walls
as either non load-bearing
panels
for either interior of exterior applications of the building.
result of these large price variations is due to the fact
The
400
the prestressed concrete slabs are mass produced on
that
to
cut
be
Ily
economica
be
can
and
beds
casting
600*
to
are
lengths while the precast concrete wall panels
specified
to
designed to designer*s specifications with reqards
custom
size, color, shape and texture.
possible cost reduction can be attrib uted to the fact
Another
The
eliminated.
completely
be
can
walls
foundation
that
the
onto
rectly
di
wall panels can bear
concrete
prestressed
in
money
and
me
ti
saves
which obviously
footings
foundation
expensive formwork.
101
8.0 EVALUATION
& CONCLUSION
102
The research thus accomplished was done at a conceptual level,
and
idea
top surface. It is an original
the
skimming. over
into
refined
and
developed
development, which could be further
a marketable new methodology of construction.
research would need to be done in the design flexibility
More
this system. Some of the questions that could be addressed
of
are:
-How high can one build with this system?
and
single
a
the load-bearing walls from
offset
one
-Can
straight wall plane?
-How would this system comply with the building codes?
the
determine
to
necessary
be
would
calculations
-What
structural sizes of the componets?
What are the cost analysis of this system that could provide a
justification to its applicability in real practice?
regarding
at
could bve looked
investigation
thorough
What
various finishes and claddings?
manifests
conclusion, based on this research, this system
In
context
vast adaptability in today*s construction market
its
with a substantial savings.
103
APPENDIX
104
MILESTONES
OF EVENTS AND DEVELOPMENTS IN NORTH AMERICAN
PRESTRESSED CONCRETE INDUSTRY (1939-1958)
Summarized
of
events
listing
is
a
chronological
below
linear
of
use
practical
of
the
influencing
development
the
prestressed
of
concrete in the United States and other parts
the western hemisphere.
YEAR
EVENTS
1939
First experimental prestressed concrete piles
driven by the Raymond Concrete Pile Corporation
in New York Harbor.
1944
Roebling engineers begin study of
steel and research in prestressed
1946
Prestressed concrete floor slab designed by
Roebling is complete in Roebling's Chicago
warehouse. First prestressed concrete structure
in the United States and first use of Roebling
materials specifically developed for
prestressed concrete, such as factory-made
prestressed cable assemblies consisting of
cold-drawn hot-galvanized acid steel wire,
and specially designed end terminals.
1946
Tests of three sets of four prestressed concrete
beams begin at Tulane U niversity under the
direction of Professor Walter
Blessey.
1947
Lumberville suspension bridge completed. Floor was
prestressed by means of Roebling*s 1/2 in. (12.7
mm) diameter high strength rods having threads at
their ends for prestressing and anchoring.
1947
to the United
visit
Professor Magnel's first
States (sponsored by the Belgian American
Educational Foundation).
1949
Rio Paz suspension bridge, connecting Guatemala to
El Salvador, open to highway traffic. It features
precast prestressed concrete floor slabs similar
to the Lumberville bridge.
1949
Start of fire tests on prestressed concrete
elements at Korchamwood, Great Britian by the
British Joint Fire Research Organization
1949
Start of- construction of the substructure of the
Walnut Lane Bridge and of the manufacture at the
site of the full-sized 160 ft. (48.8 m) long test
girder. First use of stress-relieved wire, an
prestressing
concrete.
105
American
innovation
(Roebling).
1949
Start of test to failure of full-sized Walnut Lane
test girder (October 25,1949). Beginning of site
casting of actual girders.
1949
Concrete Products Company of America starts
production of box girders in America's first
pretensioning plant, at Pottstown, Pennsylavania.
1950
Fayetteville, Tennesse Stadium. Use of Roebling
galvanized prestressed concrete strands and anchor
fittings.
1950
Turkey Creek Bridge, Tennessee. Completion of
first American prestressed concrete bridge using
concrete blocks and Roebling developed prestressing
materials.
1951
Fritz Research Laboratory at Lehigh University,
Bethlehem, Pennsylvania, begins tests on box
girders. Sponsored jointly by the Department of
Highways of Pennsylvania and Roebling. The program
was to last more than 20 years, continuosly.
1951
Formation of Precompressed Concrete Company Ltd.
(PRECO), first Canadian firm entering the
prestressed concrete field.
1951
Illinois Cooperative Highway Research program was
conducted at the University of Illinois, under the
direction of Professor Chester Siess. Questions
and answer session at the AASHO Committee
meetings on Bridges and Structures and
Bureau of Public Roads. It marks the beginning
of University of Illinois' research in
prestressed concrete.
1951
First United States National MIT sponsored
prestressed concrete conference.
1951
First American pretensioned prestressed concrete
bridge using non-stress-relieved strands as
manufactured by American Steel and Wire
Corporation completed in Hershey, Pennsylvania.
1951
Completion of first California prestressed
concrete foot bridge using headed wire.
1952
Completion in Mid-West of first buildings using
prestressed girders and permanent slabs stressed
by headed wires.
1952
Bureau
of Public Roads
(now
Federal
Highway
106
short "criteria"
Administration) publishes its
be used in the design of post-tensioned
prestressed concrete bridges.
to
1952
The Fritz Laboratories at Legigh University
published their first Progress Report in the
program of prestressed concrete research begun
in 1951. It was to give the impetus for the
construction of the prestressed concrete box
girders.
1953
September 10, formation of Prestressed Concrete
Development Group of Canada.
1953
Prestressed concrete research programs began on a
large scale on a systematic basis at a number of
leading American Universities in addition to
Lehigh University.
1953
University of Florida, Gainsville, Florida - In
cooperation with the Florida State Roads
Department: A study concerning plastic flow and
shrinkage of prestressed concrete. Fourteen such
prestressed concrete girders cast at various Florida
bridge construction sites were held under
observation for -several years.
1953
University of Illinois, Urbana, Illinois, with the
Illinois Division of Highways and the U.S. Bureau
of Public Roads - As Research Associate Professor
of Civil Engineering, Professor Chester Siess
was extremely interested in shear strength of
prestressed concrete beams. Consequently, a most
elaborate program was established. Much of the
work was the responsibility of Eugene Zwoyer, then
Research Associate in Civil Engineering.
1953
University of California - Beginning with the on
site testing of the Arroyo Seco Pedestrian Bridge
in 1951, continnuing throughout 1952, laboratory
tests on prestressed concrete under the simulus of
Professor T.Y. Lin were in full swing by 1953. At
that time, full emphasis was on prestressed
concrete thin shells and flat plates. Findings
were to be the basis for the subsequent design
and construction of the cantilever thin shell
roof for the Caracas Stadium for which Felix
Kulka of T.Y. Lin International was responsible.
1953
Portland Cement Association Research and
Development Laboratories, Skokie, Illinois - At
PCA*s laboratories, consideration was being given
commence large research programs to include full
size girders, all under leadership of Dr. Alan
to
107
Bates, Dr. Eivind Honestad and Dr. Alan Mattack.
Reports of many tests were published by PCA.
1954
January 28, 1954 Canadian Conference on Prestressed
Concrete at University of Toronto. Professor Magnel
attended as did many Canadian and American engineers.
Particularly valuable were the tests on full-sized
beams reported by Cleveland's Austin Company.
1954
Use of the first time
ready-mix concrete.
1954
Publication by the Bureau of Public Roads of the
revised and expanded "Criteria For Prestressed
Concrete Bridges" for both pretensioned and
post-tensioned concrete.
1954
Founding of Prestressed Concrete
1954
Prestressed Concrete Institute published the
edition of the Tentative Specifications for
Pretensioned Prestressed Concrete.
1955
Bureau of Public Roads, Highway Research
Board and others complete arrangements for
construction of.$12 million (increased before
completion of Project to $27-million) road
test project of AASHO, in Ottowa, Illinois.
Project included prestressed concrete bridges.
In 1962, AASHO revealed results in an extensive
three-volume report. At least three sets of data
influenced subsequent prestressed concrete
bridge design in that tensile stresses would be
allowed in concrete prestressed with strands.
(Up to then no bottom tensile stresses were
allowed at midspan of girders.)
1957
First World Conference of Prestressed Concrete
at San Francisco sponsored by the PCI with the
cooperation of National Professional Societies.
1958
Publication by the ACI-ASCE Joint Committee 323
of the Tentative Recommendations for Prestressed
Concrete.
in Canada of 5000 psi
Institute.
first
108
PROPERTIES
PECULIAR TO PRESTRESSED CONCRETE
Shrinkage
fami lar
of concrete is a process known to everyone
Shrinkage
vol ume
total
its
cures,
concrete
As
reinforced concrete.
with
three
all
in
shrink
to
tends
it
and
slightly
decreases
dimensions.
from
When
the tension in pretensioned strands is transferred
compressive
anchorages to the concrete members, the
external
all
exist ing
the
closes
concrete
in
the
created
force
cracks and both the concrete member and the stra nds
shrinkage
of
the
widths
to the sum of the
amount equal
an
shorten
est
great
ge
is
cracks. Although the rate of shrinka
shrinkage
t
ime
some
for
is first cast, it continues
member
when
the
ing
continu
the
Since
operation.
prestressing
after
th e
in
now
is
which
concrete
the
in
cracks
cause
cannot
shrinkage
fi
na
I
the
In
shortening.
additional
causes
it
compressi on,
the pretensioned strands shorten an amount equal to
analysis,
the total shrinkage. This shortening causes a reduction of the
tensile stress in the strands.
Elastic Compression
compression of the concrete member takes place as
Elastic
force is applied. As in any elastic material
prestressing
is
a function of the modulus of elasticity of
magnitude
concrete and the intensity of the compressive stress.
the
its
the
the
when
tension
is under initial
Since
the
pretensioned
strand
the
it,
to
bonded
is
stress
member under zero
concrete
shortens an amount from the anchorages to the concrete member.
Creep
concrete,
of
Creep
shortening
inelastic
by
a
is
caused
It
func
a
is
magnitude
tendons
Pretensioned
creep.
is
flow,
plastic
often referred to as
which takes place over a period of time.
its
and
stress,
compress ive
constant
stress.
that
of
tion of the intens ity
entire
the
shorten an amount equal to
Relaxation
of
cause
tendons is the fourth
of
prestressing
Relaxation
initial
at
an
used
are
tendons
these
Since
loss.
stress
tension
of 65 to 70 percent of their ultimate strength, they,
high
constant
creep or pl astic flow to the
a
undergo
too,
those
from
different
are
somewhat
however,
Conditions,
stress.
in the concrete. If a weight were hung on a tendon to create a
the
strength,
70 per cen t of its ultimate
to
equal
stress
member
would slowly elongate or creep as the concrete
tendon
109
a
In an actual structure the tendon is not held at
shortens.
As
it is not even held at a constant length.
load;
constant
the concrete member shortens from the factors mentioned above,
the tendons shortens too. There is a certain amount of plastic
a
cause
cannot
it
since
which,
tendon
the
within
flow
reduction in stress is called "relaxation."
110
MATERIALS OF CONCRETE
Properties
In reinforced concrete structures the usable concrete strength
tensile
the
by the behavior of the member. When
limited
is
psi,
in the reinforcing steel exceed 18,000 or 20,000
stress
deflection.
and
begins to show excessive cracks
member
the
these
develop
concrete is strong enough to
3,000-psi
Since
seldom
are
strengths
reinforcing, higher
the
in
stresses
spec if ied.
of
used in prestressed concrete, although made
concrete
The
full
same basic ingredients, is much stronger, since its
the
strength can be utilized. In this case the governing factor is
of
made
majority of members are
A
fabrication.
economical
concrete, although some fabricators are appreciably
5,000-psi
of
strengths and most specifications permit a minimum
higher
psi.
4,000
High-strength concrete has several advantages:
1. A smaller cross-section area can be used to carry a given
instances
many
in
dead weight and
less
means
This
load.
shallower members, giving more clearance.
2. Its higher modulus of elasticity decreases camber, which
is frequently a problem in-prestressed concrete because of the
relatively high negative moment that exits under the dead-load
reduces
also
elasticity
of
modulus
high
The
condition.
stress
in pretensioned members cuts down the
and
deflection
loss due to elastic shortening.
5,000
E,= 33 w
4,000
.a
3,007.,00
0
Unit weight w pcf
I11
3. Members can be prestressed and equipment released for the
compressive
required
in minimum time because the
pour
next
reached
of concrete at time of initial prestress is
strength
In some cases fabricators of pretensioned members use
sooner.
a mix which gives a higher compressive strength of concrete at
pouring
maintain
to
time
in
prestress
initial
of
time
schedule.
4. In bridges and other members exposed to freezing or salt
plus
density
and
high strength
of
combination
the
spray
virtually
concrete
prestressed
makes
cracks
from
freedom
maintenance-free.
Placing
for
aids
several
employ
fabricators
concrete
Prestressed
achieve
to
concrete
low-slump
high-strength
the
handling
satisfactory placement and rapid curing.
standard equipment
are
Vibrators
are frequently
screeds
Vibrating
such as double T*s and channels.
for all
used on
type.
work of this
members
area-type
cement and admixtures such as P lastiment
are
entraining
Air
the
ma intaining
the workablity while
increase
to
employed
beca use
and ultimate strength is av oided
ratio
water-cement
of
source
a
is
the rich mix
paste *in
cement
extra
the
additional shrinkage.
Curing
is
an
equipment
permit frequent reuse of
Rapid
curing
to
prestressed
factor in the economical producti on of
important
39
and especially of the pretensioned type. Figure
concrete
a
on
curing speed obtained by s team curing
the
illustrates
and
under
pipes
through
hot
oil
located
circulating
typical
h igh-early-strength
use
Many
concrete.
curing
the
beside
cement.
Calcium
chloride
existing test data
properties of high
is
not used to accelerate
action is
indicate that its
strength tendons.
because
curing
damaging to the
112
6,000
5,000
PROCEDURE
'a
CL
1- Delay steam 4 to 6 hr
~~2- Raise steam 1* per min to 145* F
4,000
:E
3-Hold steam at 1450 for 18 hr
MIX
Cement 658 lb
Sand 1,195 lb
Stone 1,908 lb
Water 34.7 Gal
03
a)
3,000
0.
u
Plastiment 21 to 28 oz
1,000
0
0
4
8
12
16
20
24
28
Age, days
Fig.
39
113
Lightweight Concrete
members
Prestressed
concrete
fabricated satisfactorily from
that are pretensioned
light-weight concrete.
can
be
and
concrete
betwe en regular-weight
chief
differences
The
concrete of the same ultimate strength are in the
lightweight
elastic properties.
Shortening of lightweight concrete due to creep plus shrinkage
regul ar-weight
of
shortening
than the
is
greater
usuall y
concrete
under similar conditions, but with properly designed
in
the
for
not excessive and can be provided
is
mixes
it
design.
of many lightweight aggregates are such that it is
Properties
it
making
thus
their water content,
measure
to
difficult
sl ump
to
know how much water to add to the mix. A
difficult
a
obtain
to
as a check. In order
used
sometimes
is
test
as
product it is often desirable to use regular sand
uniform
the
fine aggregate even though it does increase the weight of
the finished product.
products.
of lightweight aggregates know their own
Producers
They can recommend mixes and handling methods to give concrete
with the design properties. They should also have test reports
in
be
expected
and shrinkage can
creep
what
indicate
to
concretes made from their product.
Prestressed concrete members made of lightweight concrete have
of
made
members
identical
than
endurance
fire
a
longer
One possible exception is thin slabs
regular-weight concrete.
heat
than 3 in.) in which fire rating is determined by
(less
transfer through the slab.
114
TENDONS
General
Properties
in
minimize the drop
for high-strength tendons to
need
The
force due to stress losses. Satisfactory tendons
prestressing
from
and
wires
of
combinations
or
wire
from
made
are
special
bars, all of which are fabricated with
high-strength
from
proiperties. These tendons differ
concrete
prestressed
the
meet
to
order
in
ways
several
in
steels
other
most
concrete.
prestressed
of
requirements
particular
in
essential
is
tension
initial
to
elongation
Uniform
the
is
Fig 40
force.
prestressing
accurate
an
obtaining
uncoated
0.196-in.-diameter
a
of
curve
stress-strain
shape
general
(Its
wire.
concrete
prestressed
stress-relieved
tendons.)
concrete
prestressed
of
types
all
of
is typical
For all practical purposes, this curve is a straight line to a
psi
175,000
initial tension of 165,000 to
the
above
point
used for 0.196-in. wire. Tendons do not have a yield
normally
continues
like that of ordinary steel where elongation
point
the
of stress. They do reach a point where
increase
without
large
remains
and
rapidly
of strain to stress increases
ratio
is
the tendon fails. This change in slope of the curve
until
the
a necessary property. When a beam is overloaded and
also
tendon
the
ultimate,
approaches
tendon
the
in
stress
causing a visible deflection which warns impending
elongates,
fai lure.
In addition to high strength and special elastic properties, a
high
must have a low coefficient of relaxation.at the
tendon
stresses used.
7,000
240,000
220,000
6,000-------
200,000
5,000
180,000
160,000
'k
:- 4,000
140,000
0
4;
0
120,000
100,000
Stress-strain Curve
0.196" Diameter Uncoated Stress-relieved
Prestressed -concrete
Minimum Ultimat
-Wire
1Strength = 250,000 psi
80,000
60,000
40,000
40,000
3,000
2,000
i,000
20,000
0
0---------o:ooo5o
d a0oooo
Elongation, in. per in.
0-
Elongation, in.per in.
Fig.
40
115
Wire
high-carbon
a
wire is made by drawing
concrete
Prestressed
As
steel rod through several conical dies.
round
hot-rolled
and
the rod passes through each die, its diameter is decreased
the
length is correspondingly increased. In the process,
its
crystals that made up the rod are drawn out into long parallel
strenath.
give wire its extremely high tensile
which
fibers
properties
drawn wire does not have the uniform plastic
Cold
elongate
in the prestressed concrete. As the crystals
needed
yield
they develop stresses in excess of their
fibers,
into
The resulting wire is made up of fibers which are full
point.
the
stresses. When a tensile load is applied to
internal
if
each fib er elongates the same amount. The stress due to
wire,
elongatio n is added to the internal stress, and soon the
this
fiber with the highest internal stress reaches the point where
of s train to stress increases rapidly. From here on
ratio
its
will
fiber wil I elongate with the others but its stress
this
the
increase
so rapidly. Since the internal stresses in
not
various fibers are not uniform, first one fiber, then another,
resulting
The
point.
yield
the
reach
another
will
then
load-e longation curve of the wire is not uniform.
The internal st resses in the cold drawn wire are eliminated by
is
it
to a stress-relieving pr ocess in which
it
subjecting
a
short
to a mo derate temperature (750* to 850* F) for
raised
and
of time (15 to 30 sec.). This is not heat-treated
period
any
to
wire
the
of
the ultimate strength
chan ge
not
does
desired
the
has
which
degr ee. It does create a wire
noticable
internal
of
because it is free
properties
elasti c
uniform
stresses.
the
strength,
up to 70 per cent of its ultimate
stresse
At
of elasticity of uncoated stress-relieved prestressed
modulus
this
While
is
approximately 29,000,000 psi.
wire
concrete
is
accurate for design calculations, it
is sufficiently
value
recommended thgat the stell fabricator*s load-elongation curve
elongation
particular wire be used in computing the
the
for
required in jacking wires to a specific tension.
Seven-Wire Strand
strands
concrete
stress-relieved
uncoated
Seven-wire
normally
tendons
the
are
to ASTM Designation A 416
conforming
used in pretensioned bonded members. F ig 41 is a photograph of
a seven-wire strand and Fig 42 is the load-elongation curve.
Each
strand
is made up of
seven cold drawn wires.
The
center
116
wire is straight, and the six. outside wires are laid helically
around
it.
All six outside wires are the same diameter,
and
the center wire is slightly larger. The difference in diameter
is sufficient to guarantee that each of the outside wires will
bear
on and grip the center wire. This is an important detail
in
members
where
the
tension in the
strand
is
developed
through
bond. The six outer wires are bonded to the
concrete
both
by adhesive bond and by mechanical bond of the
concrete
in
the
valleys between the wires. Under tension each of
the
outer
wires
bears
on
the center wire,
and
the
resulting
friction
makes the center wire elongate with the outer wires.
If
the center wire were too small, the outer wires would bear
the
center
each
other to form a pipe through which
against
wire would slip without carrying any load.
the seven wires are formed into a strand, the strand is
After
subjected
to
a
stress-relieving process. The
result
is
a
internal
elastic properties and free
of
strand
with
ideal
stresses.
Satress-relieving
the
individual
wires
before
the
does not produce a satisfactory strand because
stranding
outer
wires are subjected to severe twisting in the stranding
opertion,
which creates internal stresses. These are
removed
only when the stress-relieving operation follows the stranding
operation.
Fig.
41
24,000
22,000
20,000
18,000
16,000
. 14,000
6
12,000
a
3 10,000
8,000
6,000
4,000
2,000
Nominal diameter -
} in.
Guaranteed minimum ultimate- 20,000 lb
Nominal area -0.0799 sq in.
Elongation in 10 ft at recommended
prestressing load (14,000 lb)-0.750 in.
0)
o
o o0
6 6 6 6 6 6 6 6 6 6 6 6 6
Elongotion, in /in.
Fig.
42
117
ACOUSTICAL PROPERTIES
General
a
basic purpose of architectural acoustics is to provide
The
clearly
environment in which desired sou nds are
satisfactory
(noise)
by
the intended listeners and unwanted sounds
heard
are isolated or adsorbed.
determine
conditions, the architect/engineer can
most
Under
the acoustical needs of the space and then design the building
both
to
satisfy those needs. Good acoustical design utilizes
and
barriers
sound
surfaces,
reflective
and
absorptive
isolators. Some surfaces must reflect sound so that
vibration
the loudness will be adequate in all areas where listeners are
sound
surfaces absorb sound to avoid echoes,
Other
located.
isolated
is
and- long reverberation times. Sound
distortion
floor-ceiling
and
is not wanted by selecting wall
it
where
equipment
generated by mechanical
Vibrations
constructions.
must be isolated from the structural frame of the builing.
The problems of sound insulation are usually considerably more
complicated than those of sound absortion. The former involves
of
orders
level, which are of greater
sound
of
reductions
large
These
be achieved by absorption.
can
than
magnitude
of sound level from space to space can be achieved
reductions
also
by continuous, impervious barriers. If the problem
only
to
necessary
be
may
it
sound,
borne
structure
involves
into
the
discontinuities
layers
or
introduce
resilient
barriers.
absorbing materials and sound insu
Sound
There
purposes.
different
for
used
from an 8 in. concrete wall;
absorption
insulation
is not available from porous,
applied to room surfaces.
be
may
that
the basic mechanisms of
that
recognize
sound insulation are quite different.
lating materials
are
is
not
much
sound
similarly, high sound
lightweight material
It
is
important
to
and
sound absorption
Sound Transmission Loss
Sound tran smission loss measurements are made at 16 frequences
at one-thi rd intervals covering the range from 125 to 4000 Hz.
performance
desired
of
specification
To
simpli fy
Class
Transmission
single number Sound
the
characteri stics
(STC) was developed.
ceiling
produces
a wal I, floor or
reachi ng
sound
Airborne
reduced
with
radiated
is
and
el ement
in
the
vibrations
on the other side. Airborne sound transmission loss
intensity
their
walls and floor-cei ling assemblies is a function of
of
weight, stiffness and v ibration damping characteristics.
118
sound
Weight is concrete's greatest asset when it is.used as
design,
but
different
insulator.
For
sections
of similar
for
each
STC
increases approximately 6 units
the
weights,
43
doubling of weight as shown in Fig.
both
of
results
test
acoustical
The
impact
insulation of
loss
and
transmission
hollow-core slabs are shown in Fig. 44
sound
airborne
in.
6
and
8
Table
1. presents the ratings for precast concrete walls and
various
assembly
The
effects of
assemblies.
floor-cei I ing
are
improvements
The
treatments
in Table 2
shown
are
slightly
but in some cases the total effect may be
additive,
less than the sum.
Absorption of
Sound
The
sound
absorption
frequences
individual
coefficients (NRC).
coefficien t
an
or
as
be
can
average
at
specified
absorption
of
A
dense non-porous concrete surface typically absorbs 1 to
2
There
of
0.015.
an
NRC
has
and
of
sound
incident
of
percent
surfaces
are
specially fabricated units with porous concrete
provide greater absortion. In the case where additional
which
absorption of precast concrete is desired, a coating of
sound
acoustical material can be spray applied, ascoustical tile can
can
be
adhesive, or an acoustical ceiling
applied
with
be
Most of the spray applied fire retardant materials
suspended.
and
used
to increase the fire resistance of precast concrete
floor-ceiling systems can also be used to absorb sound.
other
Most
0.75.
of the sprayed fiber range from 0.25 to
The
NRC
cementitious types have an NRC from 0.25 to 0.50.
Acceptable Noise Criteria
As
a
rule,
a
certain amount of
continuous
sound
can
be
level
An
"acceptable"
it
becomes noise.
before
tolerated
with
the
room
occupants
nor
interferes
neither
disturbs
communication of wanted sound.
The
most generally accepted and commonly used noise
criteria
(PNC)
Criteria
as the Preferred Noise
are
expressed
today
of
extensive
45
These values are the
result
curves,
Fig
sound
pressure
based
on the human response to both
studies
level and frequency and take into account the requirements for
represent
...
The figures in Table
intelligibility.
speech
with
goals.
They can also
be
compared
general
acoustical
in
assist
to
specific rooms
in
levels
noise
anticipated
evaluating noise reduction problems.
as
such
be from an exterior source
may
sounds
Undesirable
in
as
speech
be
generated
may
automobiles or aircraft, or they
They
apartment.
or
music
in
an
adjacent
classroom
an
adjacent
119
(a) Sound Transmission Class (STC)
1/4"
1/80"
1/21" Air Space
.030 Vinyl
1/4 "
1/81"
1/4"
1" Air Space
1/4"
35
3/4"
36
1/4"
Laminated
1"
1/2"
1/2"
1/4"
Laminated
38
-
1/2" Air Space
-
2 3/4" Insulated glass
4 3/4" Insulated glass
6 3/4" Insulated glass
1/2"
-
1/4"
1 " Plate or Float
1/4"
-
-
1 1/2" Insulated glass
3/4 " Plate or float
1 " Insulated glass
STC
23
28
31
31
34
-
-
1141" Plate or float
1/2 " Plate or float
1 " Insulated glass
1/4 " Laminated
Outside
Light
1/8"
Construction
Space
Inside
Light
Type and Overall
Thickness
1/8 " Plate or float
-
2" Air Space
4" Air Space
6" Air Space
1/4"
1/4"
1/4"
37
39
40
42
(b) Transmission Loss (dB)
Frequency (Hz)
125
160
200
250
315
400
500
630
800
1/4 inch plate glass -
24
22
24
21
24
23
21
23
26
1000
1250
1600
2000
2500
3150
4000
33
36
37
39
40
40
29
31
33
36
40
41
44
28 STC
27
1 inch insulating glass with 1/2 inch air space - 31 STC
25
30
25
29
22
26
24
20
27
27
32
30
34
35
33
1 inch insulating glass laminated with 1/2 inch air space - 38 STC
41
40
38
38
37
37
35
34
31
28
Table 2
-
65
60
flat or ribbed panels.
tees with topping,
hollow core slabs
z
0
O
----
50
z
ST - 0.1304 W + 43.48
statistical tolerance ±2.5 STC
z
0
0/
45
40
40
90
80
70
60
50
WEIGHT PER UNIT AREA - (W) IN.
100
Fig. 43
120
Assembly
No.
STC
lIC
49
55
-
58*
-
63*
58
54
-
Wall Systems
1
2
3
4
5
6
4 in. flat panel, 54 psf
6 in. flat panel, 75 psf
Assembly 2 with wood furring, 3/4 in. insulation and 1/2 in.
gypsum board
Assembly 2 with 1/2 In. space, 1 5/8 in. metal stud row, 1 1/2 In.
Insulation and 1/2 in. gypsum board
8 in. flat panel, 95 psf
14 in. prestressed tees with 4 in. flange, 75 psf
Floor-Celling Systems
7
14 in. prestressed tees with 2 in. concrete topping, 75 psf
54
24
8
Assembly 7 with carpet and pad, 76 psf
Assembly 7 with resiliently suspended acoustical ceiling with
1 1/2 in. mineral fiber blanket above, 77 psf
54
72
59
51
10
11
12
Assembly 9 with carpet and pad, 78 psf
8 in. hollow-core prestressed units, 57 psf
Assembly 11 with carpet and pad, 58 psf
59
50
50
82
28
73
13
8 in. hollow-core prestressed units with 1/2 in. wood block
flooring adhered directly, 58 psf
51
47
Assembly 13 except 1/2 in. wood block flooring adhered to 1/2 in.
sound-deadening board underlayment adhered to concrete, 60 psf
52
55
15
Assembly 14 with acoustical ceiling, 62 psf
59
61
16
4 in. flat slabs, 54 psf
49
25
17
5 in. flat slabs, 60 psf
52*
24
18
6 in. flat slabs, 75 psf
55
34
19
8 in. flat slabs, 95 psf
58
34*
20
10 in. flat slabs, 120 psf
59*
31
21
5 in. flat slab concrete with carpet and pad, 61 psf
52*
68
22
10 in. flat slab concrete with carpet and pad, 121 psf
59*
74
9
14
*Estimated values
Table
1
121
Impact Insulation
Sound Transmission Loss
70 --
60--
-o
8in.hollow core, STC-50
C',
C',
0
-. 1
-j
50---
w
z
0
C')
40 --
-
6in.hollow core. STC-48
z
z
0
0
-
30-
--
--
-
a.,
I-
-
20--
10.
c.4 0
0
'4
)
C4
00000V0
a0
-
An 0
0
0
q1W 00
'
4'0
0
0
n
0
C
0
0
0
0
'00
FREQUENCY, Hz
Fig.
44
woso
...
60
1101
-.
'-,0
-
PNC 65 ver y
,PNC
60
noisy
PNC 55 nos
.:NC 50
401moderate
PNC
PNC 45
4o
ao
0
2
25 ver
-PNC
PNC 15
threshold
of hearing
OCTAVE BAND CENTER FREQUENCY, Hz
Fig.
45
122
may be direct impact-induced sound such as foot-falls on
also
roof
a
lightweight
on
impact
rain
above,
floor
the
construction or vibrating mechanical equipment.
the designer must always be ready to accept the task of
Thus,
as
sound
many potential sources of intruding
the
analyzing
at
to
their frequency characteristics and the rates
related
to
be
is
The
level of toleration that
occur.
they
which
be
must
space
the
occupy
will
who
those
by
expected
of
charcteristics
Fig.
46 gives the spectral
established.
exterior noise sources. Fig. 47 provides similar data
common
on common interior noise sources.
Establishment of
Noise
Insulation Objectives
minimum
to
the
is
specified as
control
acoustical
Often
values of the dividing partition system. Municipal
insulation
of
Department
lending institutions and the
codes,
building
STC
airborne
both
list
(HUD)
pment
Develo
Urban
and
Housing
living
different
for
values
IIC
impact
and
values
As an examp le, "HUD Minimum Property Standard environments.
Multiple Housing" has the following requirements:
STC
Location of Partition
Between
Between
living units
living units and p ublic
Location of
Between
Between
space
Floor-Ceiling
living units
living units and
public space
45
50
STC
I IC
45
50
45
50
the objectives are established, the designer then should
Once
and
1.,
Table
data, e.g., Fig 43 or
available
to
refer
select the system which best meets these requirements. In this
can
systems have superior properties and
concrete
respects,
with minimal effort comply with these criteria.
Composite Wall
Considerations
otherwise
an
Doors
and
windows
are often the weak link in
effective sound barrier. Minim al effects on sound transmission
of
will be achieved in most cases by a proper selection
loss
2
Mounting of the glass in its frame should be
Table
glass,
the
reduce
to eliminate noise leaks and to
with
care
done
vibrations
glass plate
Sound
transmission loss of a door depends on its material and
and the sealing between the door and the frame.
construction,
There is a mass law dependence of STC on weight (psf) for both
wood and steel doors. The approximate relationships are:
For steel doors: STC = 15 + 27 log W
the
doors: STC = 12 + 32 log W where W = weight of
wood
For
123
120
jet aircraft takeoff
5100ft
100
bus
w
80
heavy truck -20 f t
w
propeller aircraft
akoff-500 ft -
cc
60
automobiles - 20 ft
LU
40
z
0
W,
20
0
63
125
250
500
1000 2000
4000 8000
FREQUENCY, Hz
Fig.
46
120
S100
80
in
w
60
40
C
20
20
20
63
125
250
500
1000 2000 4000
8000
FREQUENCY, Hz
Fig.
47
124
door, psf
These
are
relationships
deviation can be expected for
48
Fig
isolation
elIements,
purely
empirical
any given door.
and
a
large
acoustic
the
effective
used to calculate
be
can
of
a
composite
wall system which contains
of
a
each with known individual transmission loss data.
Leaks and Flanking
with
an
otherwise
The
performance
of
a
building section
small
can be seriously reduced by a relatively
STC
adequate
hole
or
any
other
path which
allowssound
to
bypass
the
paths
barrier. All noise which reaches a space by
acoustical
called
flanking.
through
the primary barier is
other
than
windows,
flanking paths are opennings around doors or
Common
connections,
and
television
electrical outlets, telephone
at
and duct penetrations.
pipe
and
Although not easily quantified, an inverse re lationship exists
between the performance of an element as a pr imary barrier and
its propensity to transmit flanking sound. In other words, the
probability of existing flanking paths in a c oncrete structure
is much less than in the one of steel or w ood frame.
Vibration
Isolation
equipment
with
of
vibrations
produced
by
The
isolation
be
frequently
can
starting forces
of
operation
unbalnced
concrete
heavy
by
mounting the equipment on a
accomplished
is
type
resilient supports. A slab of this
on
placed
slab
called an inertia block.
gravity
blocks can provide a desirable low center of
Inertia
large
bt
generated
as
those
for theusts such
and
compensate
a
"house
weight,
less
unbalanced
with
equipment
For
fans.
slab is sometimes used below the resilient mounts to
keeping"
a rigid support for the mounts and to keep them above
provide
inspect.
to
where they remain cleaner and easier
the
floor
glass
This
slab may also be mounted on pads of precompressed
fiber or neoprene.
If
static
deflection
of
the floor is
more
than
a
small
mounts,
resilient
the static deflection of the
of
fraction
of
the
part
danger that the floor will act as
is
a
there
system. Prestressed concrete floors supporting such
vibrating
125
equipment
can
be
built
stiff
to
avoid
this
effect.
A
deflection
much less than the o the rwise satisfactory 1/360 of
the
span,
away
from
its
c ent er,
also
reduces
static
deflection.
ca
o
1--
2
of total area
of wall occupied by
window or openin
-Percent
o
S-door,
z
o
10
10
-
15 15-e
200
30
40
-j
I
50
60
-
1
2
-
3 4 5 6 78910 15 20
30 40 5060
DECIBELS TO BE SUBTRACTED FROM TL OF WALL
FOR EFFECTIVE TL OF COMPOSITE BARRIER
Fig. 48
126
THERMAL
PROPERTIES
General
heat
and standards prescribe in many ways the
codes
Thermal
is
it
buildings. Therefore,
for
requirements
transmission
heat
important to have basic knowledge about the heat loss and
design
many materials. Some of the fundamentals and
of
gain
losses
heat
the
compare
and
to
analyze
needed
are
that
aids
envolopes.
building
and heat gains through
unique
prestressed concrete construction have a
and
Precast
storage
thermal
and
thermal inertia
with
their
advantage
codes,
some
in
recognized
is
advantage
This
properties.
heavier
to account for the bennifits of
procedures
however,
materials are not usually given.
given
trend is toward more insulation with little regard
The
that
assuming
Before
to
its total impact on the energy saved.
area,
glass
less
is needed, mass effects,
insulation
thick
be
should
controlled ventilation
and
infiltration
reduced
building
include
may
considerations
Further
considered.
from
reflections
or
shading
color,
exterior
orentation,
vegitation,
or
surfaces
surrounding
structures,
adjacent
direction
aspect ratio, number of stories, and wind
building
and speed.
that
noted the information and design criteria
where
Execpt
of
"Handbook
from or derived from ASHRAE
taken
are
follow
Fundamentals", also known as the ASHRAE Handbook, and from the
Building
90-75, "energy Conservation in New
Standard
ASHRAE
Design", also known as the ASHRAE Standard.
Thermal
Properties of Materials, Surfaces
and Air Spaces
based
The
thermal properties of materials and air spaces are
of
number
the
established
tests
The
tests.
state
on
steady
to
units (Btu) that pass from the warm side
thermal
British
temperature
degree
per
hr
ft per
sq
per
side
cool
the
results
either side of the item being tested. The
difference
of the tests determine the conductivity, k, per inch thickness
compound
non-homogeneous
For
sections.
for
homogeneous
conductance,
and air spaces the tests determine the
sections
C,
for the total thickness. The values k and C do not include
conductances. The inside surface conductance, fi, and
surface
the outside surface conductance fo, are considered separately.
The resistance method is used to determine the overall thermal
of wall, floor and roof sections. Therfore, the
effectiveness
resistance, R, i.e., the reciprocal of k, C, fi, Nd fo must be
not
are
materials
construction
of
The
R-values
known.
hand
other
the
the direction of heat flow. On
by
influenced
on
depending
the surfaces and air spaces differs
R
of
the
127
orientation,
horizontal.
of
velocity
properties.
or
s 1op ing
is whether they are vertical,
that
Also the R-values of surfaces are eff ected by the
ref Iect ive
their
by
the surfaces and
at
air
surfaces
and 4. give the thermal resistances of
3 .
Tables
3 1/2 in. air spaces. Values in Table 4 . can be used for
and
all air space thickness with very little change in the overall
flow
heat
Where
exception.
one
with
section,
of
the
R
Table
down, the procedure given in footnote 1,
is
direction
4
should be used.
used
5. gives the thermal properties of most commonly
Tab le
since
given
are
u-values
only
glass,
For
materials.
bui Iding
The
resistance.
thermal
no
almost
has
alone
the
glass
of the surfaces of the glass contribute mostly to
res istances
the U-va Iue.
weight
various
of
the thermal properties
gives
Table
6
gives
also
It
concretes.
insulating
including
concrete,
concrete
prestressed
used
the
commonly
some
of
f
o
R-values
floor, roof and wall units.
determined
and resistances are usually
conductances
Thermal
dry
oven
their
in
materials
building
for
reported
and
condition. Conductances and resistances for concrete are often
reported in its normally dry condition as well as its oven dry
concrete
of
condition
the
is
dry
Normally
condition.
an equilibrium amount of free water after extended
containing
Values
warm air at 35 to 50% relative humidity.
to
exposure
considered
in the tables are based on concrete that is
given
normally dry.
combination
should be noted that normal ly dry concrete in
It
as
R-value
same
insulation generally provides about the
with
be
noted
also
It
should
concrete.
dry
oven
insulated
equally
content,
normally dry concrete, because of its moisture
that
oven
ability to store a greater amount of heat than
the
has
dry concretes, a property somewhat beneficial when considering
dynamic thermal response of concrete.
Thermal
Storage Effects
of
roofs
and
has been known that walls
it
time
some
For
temperature
to
react
material
massive
any
or
concrete
cooling
and
and therefore reduce heating
slowly
variations
has
engineering application of this concept
however,
loads,
now
to only estimating mass effects. Computers
limited
been
it possible to better account for mass effects with hour
make
by hour calculations for 24 hours, a week, a month, or a year.
the
as
that
load computer studies show
peak
24-hour
Some
loads
of walls increases the heat flow rates and peak
weight
roofs
two
Fig 49. compares the heat gain through
decrease.
exposed
different weights but with equal U-values and
having
128
Thermal resistances, Rf, of surfaces
Still air, RU
Position
of
Direction
of
Surface
Heat Flow
Vertical
Horizontal
Horizontal
Up
-Down
Nonreflective
Surface
Reflective
Surface
Nonreflective
Surface
0.68
0.61
0.92
Moving air, RI
A (_)
B_(2)
15 mph 3(
1.35
1.10
2.70
1.70
1.32
4.55
0.17
0.17
0.17
7% mph( 4
0.25
0.25
0.25
(3) Winter design
(4) Summer design
(1) Aluminum painted paper
(2) Bright aluminum foil
Table 3
Thermal resistances, R., of air spaces 1 )
Position
of
Air
Space
Direction
of
Heat
Flow
Air Space
Mean
Temp.
*F
Reflective Surfaces
Nonreflective
Surfaces
One
SideMs
One
Side 3)
Both
SidesM
10
30
1.01
0.91
2.32
1.89
3.40
2.55
3.63
2.67
10
0.85
2.15
3.40
3.69
10
30
0.93
0.84
1.95
1.58
2.66
2.01
2.80
2.09
-
1.23
3.97
8.72
10.37
-
1.00
3.41
8.19
10.07
Temp.
Diff.
*F
Winter
Horizontal
(walls)
50
50
Horizontal
(walls)
90
Up
(roofs)
50
50
Down
Horizontal (floors)
50
Summer
Vertical
Winter
Summer
Down
(rr afs)
90
(1) For 3 1/2 iri. air space thickness. The values with the exception of those for reflective
surfaces, heat flow down, will differ about 10% for air space thickness of 3/4 in. to 16
in.
(2) Aluminum painted paper
(3) Bright aluminum foil
Table 4
129
Thermal properties of various building materials1l)
Material
Insulation, rigid
Cellular glass
Fiberglass
Mineral fiber, resin
binder
Mineral fiberboard,
wet felted, roof
insulation
Wood, shredded,
cemented in
preformed slabs
Polystyrene - cut
cell surface
Polystyrene - smooth
skin surface
Polystyrene - molded
bead .
Polyurethane
Miscellaneous
Acoustical tile
Carpet, fibrous pad
Carpet, rubber pad
Floor tile, asphalt,
rubber, vinyl
Gypsum board
Particle board
Plaster
cement, sand agg.
gyp, LW. agg.
gyp, sand agg.
Roofing, 318 in.
built-up
Wood hard
Wood soft
Wood plywood
Unit
Weight,
pcf
Resistance
For thickPer Inch
ness shown,
of thickR
ness, Ilk
8.5
4 to 9
2.63
4.00
15
3.45
16-17
2.94
22
1.67
1.8
4.00
3.5
5.26
1.0
1.5
3.57
6.25
18
2.50
Transmittance,
U
2.08
1.23
0.05
50
50
0.90
1.06
116
45
105
0.20
0.63
0.17
70
45
32
34
0.91
1.25
0.83
0.33
Glass doors & windows
Single, winter
Single, summer
Double, wintera
Double, summera
1.13
1.06
0.65
0.61
Doors, metal
Insulated, winter
Insulated, summer
0.19
0.18
for all concretes, including insulating concrete for roof fill.
(1) See Table 6.
(2) 1/4" air space.
Table 5
130
Thermal properties of concrete l)
Description
Concrete
Weight,
pcf
Concretes
including normal
weight, lightweight
and lightweight
Insulating concretes
Thickness,
In.
145
140
130
120
110
100
90
80
70
60
50
40
0.075
0.083
0.11
0.14
0.19
0.24
0.30
0.37
0.45
0.52
0.67
0.83
30
1.00
20
1.43
Normal weight
2
and solid slabs
teesa(
145
Normal weight
hollow core slabs
145
Structural lightweight
teest2 ) and solid slabs
110
Structural lightweight
hollow core slabs
(1)
Resistance, R
For thickPer Inch
ness shown,
of thickI/C
ness, ilk
110
2
3
4
5
6
8
0.15
0.23
0.30
0.38
0.45
0.60
6
8-
1.07
1.34
10
12
1.73
1.91
2
0.38
3
4
0.57
0.76
5
0.95
6
8
1.14
1.52
8
2.00
12
2.59
Based on normally dry concrete
(2) Thickness for tees is thickness of slab portion including topping, if used. The effect of the
stems generally is not significant, therefore, their thickness and surface area may be disregarded.
Table 6
131
to
identical
summer simulated temperatures.
Heating Loads
The
ASHRAE
Handbook
recognizes
the effects of
mass
on
a
building's ability to retain heat, however it does not offer a
wall
to
account for the effect. Computer studies of ten
way
show
conditions
weather
exposed to ten different
each
types
outward
flow
heat
of walls increases, the
as
weight
that
be
can
U-values
result, the steady-state
a
As
decreases.
The
to account for mass effects on walls and roofs.
modified
days
degree
the number of heating
as
change
modifications
changes. The modification M-factors are given in Fig. 50.
Cooling Loads
in
the
of
mass on cooling loads are reflected
The
effects
differences,
temperature
the
use of equivalent
by
designs
and
The TDeqw (walls)
and 8 .
as
given in Tables 7.
TDeq,
sections
the
of
weight
the
as
decrease
(roofs)
TDeqr
increases.
Building Envelope Performance and Trade-Off Considerations
component
permit
codes
and
Standard
some
ASHRAE
The
one
is, the stated overall Uo-value of any
That
trade-offs.
be
may
floor,
or
wall
roof/ ceiling,
as
such
assembly,
decreased,
components
and
the Uo-val ue for other
increased
provided the overall heat transmission for the entire building
criteria.
does
not exceed the total allowed by the
envelope
For buildings where the fl oors are not exposed to the outdoors
the allowed overall envelo pe hourly loss is:
where:
=
=
=
=
=
temperature differen ce, indoor to outdoor, F
overall area of wall s, sq ft
overall are
of roo f, sq ft
overall heat transmi ssion value of walls, Btu/hr ft2 F
overall heat transmi ssion value of roof, B tu/hr ft2 F
All values in the brackets of the equation can be
those given in the code or standard providing the
the values is not increased.
altered from
summation of
for
altering
concept is usefull particularly
The
trade-off
floor or roof criter ia without exceeding the total loss
wall,
different
for the envelope. The concept also permits
allowed
exposures.
and
south
e,
north
exampl
for
on,
Uw-values
of
elements
coup led with trade-off of
trade-offs
Component
of
such as opaque vs. glass, permit a great deal
components,
with
fewer
Also,
design.
enve lope
in
building
freedom
requirements, more efficient building design are
prescriptive
possible.
132
Heat gain comparison for light and
heavy roofs
12
-
U (t
8
--
C-
0
8
4
0-
12
20
16
24
(noon)
(midnight)
Time, hr
Fig. 49
Modification factor, M, for heating
designs (for use in modifying steady
state U-values)
0
0
'U
Degree days
Fig.
Wall temperature difference, TD
Weight of Wall
lb I ft 2
TD ,
*F
0-25
44
26-40
37
41 -70
30
71 & above
23
Table
7
50
Roof temperature difference, TD__
Weight of Roof
TD@qr
lb I ft2
0-10
11-50
51 & above
Table
*F
70
50
40
8
133
Condensation Control
is
building
on the interior of a
condenses
which
Moisture
its
or
building
the
to
damage
cause
can
and
unsightly
of
condensation
the
is
undesirable
more
Even
contents.
it
where
assembly
ceiling
or
wall
building
within a
moisture
in
not readily noticed until damage has occurred. Al I air
is
more
carrying
water with warm air
some
contains
buildings
moisture than cold air. In many buildings moisture is added to
or
laundering,
cooking,
industrial processes,
by
air
the
a
wall,
the -inside surface temperature of
If
humidifiers.
or ceiling is too cold, the air contacting this surface
floor
its
be cooled below its dew point temperature and leave
will
the
on
occurs
surface. Condensation
its
on
water
excess
surface with the lowest temperature.
the
of
humidity
relative
the
occurs,
condensation
Once
any
since
increased
be
cannot
building
a
of
space
interior
cold
the
on
simply condense
will
vapor
water
additional
an
of
temperature
inside
the
then,
effect,
In
surface.
contained
limits the relative humidity which may be
assembly
any
for
U-values
gives
51
Fig
space.
interior
an
in
relative
inside
and
temperatures
outside
of
combination
humidities above which condensation will occur on the interior
surfaces.
Relative humidity at which visible condensation occurs on inside surfaces.
Inside temperature, 70F*
1.2
100
M
La
z
0.8
20% o
---
z
cc
1
Double gi
0.6 -30
-
-Storm
w
40%
I0.4
--
50%
160
7
0.2
0
-30
-20
-10
0
10
20
30
40
OUTSIDE TEMPERATURE. F
Fig.
51
135
FIRE RESISTANCE
Introduction
prestressed concrete members can be provided with any
Precast
building
by
fire resistance that may be required
of
degree
fire
companies, and other authorities. The
insurance
codes,
of building assemblies is determined from standard
resistance
and
Testing
defined by the American Society for
tests
fire
Materials.
To insure that fire resistance requirements are satisfied, the
various
by
use tabulated information provided
can
engineer
authoritative bodies, such as Underwriters Laboratories, Inc.,
codes.
American Insurance Association and model building
the
fire
standard
of
results
on
the
based
is
information
This
other
and
ceilings
include
may
that
assemblies
of
tests
"Fire
UL
the
of
edition
1978
The
components.
building
Directory" alone provides information on more than
Resistance
concrete
prestressed
incorporating precast
assemblies,
120
members.
of
resistance
fire
of tabulated data, the
absence
the
In
be
can
concrete members and assemblies
prestressed
precast
calcultaions
These
most cases by calculation.
in
determined
based on engineering principals and take into account the
are
the
as
known
standard fire test. This is
a
of
conditions
is
It
resistance.
fire
determining
of
Design Method
Rational
the
by
part
in
sponsored
research
extensive
on
based
Portland
Concrete Institute and conducted by the
Prestressed
Cement Association and other laboratories.
Standard Fire Tests of Prestressed Concrete Assemblies
America
test of a prestressed concrete assembly in
fire
The
Standards.
of
in 1953 at the National Bureau
conducted
was
Since that time, more than 150 prestressed concrete assemblies
America.
in
tests
fire
standard
to
subjected
been
have
of
many of the tests were conducted for the purpose
Although
were
tests
the
of
most
ratings,
fire
specific
serving
whose
studies
conjunction with broad research
in
performed
prestressed
of
objectives have been to understand the behavior
these
to fire. The knowledge gained from
subjected
concrete
fire
of
lists
(1)
of
development
resulted in the
has
tests
procedures
(2)
and
components,
concrete
prestressed
resistive
for determining the fire endurance by calculation.
have
elements
types of prestressed concrete
different
Many
tees,
double
joists,
elements
These
tested.
fire
been
slabs,
tees, single tees, solid slabs, hollow-core
mono-wing
In
beams.
I-shape
and
beams,
ledger
beams,
rectangular
wall
roofs with thermal insulation and loadbearing
addition,
elements
these
also been tested. Nearly all of
have
panels
136
been exposed directly to fire, but a few tests have been
have
protection
additional
specimens that received
on
conducted
etc.
ceilings,
coatings,
from the fire by spray-applied
Fire Tests of Flexural
Elements
of
en durance
a
that the structural fire
shown
have
Tests
on
depends
t
elemen
concrete
prestressed
precast
flexural
factors, the most important of which is the method of
several
fact ors
Other
unrestrained.
or
restrained
i.e.,
support,
size and shape of the element, thicknes s of cover (or
include
the
of
ce nters
between the
distance
the
precisely,
more
surfac e),
and the nearest fire-expo sed
tendons
prestressing
as
endurance
load intensity. The fire
and
type,
aggregate
of
the
rise
temperature
for
criteria
the
by
determined
unexposed surface (heat transmission) depends pr imarily on the
concrete thickness and aggregate type.
Single
Course Slabs
unexposed
the
the temperature rise of
slabs,
concrete
For
depends mainly on the thickness and agg rega te type of
surface
unit
inc lude
factors
important
less
Other
concrete.
the
weight, moisture condition, air content, and max imum aggregate
strength,
Within the usual ranges, water-cement ret io,
size.
and age have only insignificant effects.
(heat
transmission)
of
52
shows
the
fire endurance
Fig
thickness.
and
type
slabs as influenced by aggregate
concrete
by
obtained
slab, this thickness may be
hol low-core
For
a
curves
The
width.
by
its
area
sectional
dividing the net cross
air-entrained concrete made with air-dry aggregates
represent
a nominal maximum size of 3/4 in. and fire tested when
havibg
the
was at the standard moisture condition. On
concrete
the
lightweight,
as
designed
are
aggregates
concrete
graph,
sand-lightweight, carbonate, or siliceous.
in
unit
generally increases with a decrease
endurance
Fire
of
the
infl uence
concretes,
structural
for
but
weight,
aggregate type may overshadow the effect of the unit weight.
improved
concrete, fire endurance is
For
normal
weight
for this
reason
The
size.
the maximum aggregate
decreasing
a
decrease
with
increases
cement paste content
the
that
aggregate size.
Members
Restrained Against Thermal
by
is
in
Expansion
large
a
of
beneath an interior portion
occurs
fire
a
If
to
tend
the heated portion will
slab,
concrete
reinforced
In
and push against the surrounding part of the slab.
expand
the unheated part of the slab exerts compressive forces
turn,
the heated portion. The compressive force, or thrust, acts
on
the bottom of the slab when the fire test occurs but, as
near
137
the fire progresses, the line of action of the thrust rises as
mechanical properties of th e heated concrete change. This
the
thrust is generally great enough to inrease the fire endurance
significantly.
be
expansion
to
thermal
can
of
restraint
The
effects
The thermal thrust acts in
as shown in Fig. 53
characterized
which,
force,
similar to an external prestressing
a
manner
increases the positive moment capacity.
to
the
in
bending moment capacity is similar
increase
The
effect of added reinforcement located alond the line o f action
the thrust. It can be assumed that the added reinf o rcement
of
By
this
thrust.
strength (force) equal to the
yield
has
and
magnit u de
the
to determine
possible
is
it
approach,
fire
giv e n
a
thrust to provide
required
the
of
location
endurance.
Code and Economic Considerations
to
is
of dealing with fire resistance
aspect
important
An
understand what the benefits are to the owner of a buildi ng in
his
in
incorporated
materials
of
selection
proper
the
and
code
areas,
fall into two
These
bennifits
structure.
economics.
of
codes are laws that must be satisfied regard l ess
Building
the
represent i ng
d esigner,
The
considerations.
other
any
in
the
no option in the code regulations., only
has
owner,
regulations.
these
materials and assemblies that meet
designer/owner
benefits are often overlooked by the
Economic
at the time decisions are made on the structural system.
team
through
of fire resistive construction
consideration
Proper
economic
owner
the
will provide
analysis
cost
life-cycle
bennifits over other types of construction in many areas, e.g.
under
areas
larger allowable gross
costs,
insurance
lower
and
types of building construction, fewer stairwells
certain
mortgage
longer
value for loan purposes,
increased
exits,
terms, and better resale value. To ensure an owner of the best
using
analysis
his investment, a life-cycle cost
on
return
fire resistive construction must be prepared.
of
history
the
is
considerations
theoretical
the
Beyond
es.
fir
in
actual
excellent performance of prestressed concrete
Structural integrity has been provided, fires are contained in
the area of origin, and, in many instances, repairs consist of
of
re-occupany
leading to early
only
treatment
"cosmetic"
structure.
133
Fire endurance (heat transmission)
of concrete slabs
5
4
CC,
X
z
LU
1
1'/2
5
4
3
2
7
6
SLAB OR PANEL THICKNESS, IN
Fig.
52
Axially restrained beam during
fire exposure
C.G
T
4
@ 0 Hr, T-0
1
M
M
Te
@3 Hr
(curved due to deflection of beam)
Fig.
53
139
COORDINATION WITH MECHANICAL, ELECTRICAL AND OTHER
SUB-SYSTEMS
Introduction
buildings
is used in a wide variety of
concrete
Prestressed
of
is
services
other
and
plumbing
lighting, mechanical,
with
importance to the designer. Because of increased environmental
electrical
and
of costs for mechanical
ratio
the
demands,
installations to total building has increased substancially in
recent years. This section is intended to provide the designer
satisfy
economically
to
perspective
necessary
with
the
some
and electrical requirements, and to describe
mechanical
of the installation of other sub-systems.
Lighting and Power Distribution
For many applications, the designer can take advantage of fire
resistance, reflective qualities and appearance of prestressed
structure
by leaving the columns, beams and ceiling
concrete
high
using reflective paint and properly spaced
By
exposed.
flourescent lamps installed in a continuous strip, the
output
designer can achieve a high level of illumination at a minimum
concrete
precast
these
reflective paints,
using
By
cost.
convential
as
be made as efficient
can
channels
lighting
fluorescent fixtures.
Electrical
Floors
machines,
and
other
increasing
use
of
business
The
and
adequate
for
the
need
stresses
systems
communication
communication
electricity
and
of
suppling
flexible
means
on
service.
Since
a cast-in-place topping is usually placed
prestressed
floor members, conduit runs and floor outlets can
shallow
height
buried within this topping. With
be
readily
electrical
systems, a comprehensive system can be provided in
for
conduits
thin topping. The total height of
a
resonably
1-3/8
comprehensive electrical systems is as little as
these
in. Most systems can easily be included in a 2 to 4 inch thick
electrical
as
Voids
in prestressed slabs can be used
slab.
raceways as shown in Fig 54
When
the system is placed in a structural composite slab, the
and
ducts and conduits must be carefully examined
of
effect
Tests
on
coordinated with reinforced steel.
location
their
structural
that
shown
have
ductwork
burried
with
slabs
strength is not normally impared by the voids.
of
prestressed
high load-carrying capacity
the
of
Because
high-voltage
to
locate
it
is
possible
concrete
members,
of
areas
near
the
transformers,
heavy
with
substations,
consumption with little or no expense.
140
30 AMP. 125 VOLT
ELECTRICAL. OUTLET
ELECTRICAL
PANEL
SINGLE STATION
TEEPON OR0
+P4ONOUTLET
TELEPONE
SUPPLY CLOSET
L15=04MCIL25 0
ffr
S-ke
FINISH FLOOR
2" FLOOR PILL
TELEPONE CULL CAPACITYt
30 1.4.S
CULL AREAs 27.1 SQ. IN. ('
PLUS
SLAS)
1e
Fig.
54
141
Ductwork
The
designer
may
also utilize the space
within
the
holes
inside prestressed hollow-core concrete slabs for distribution
ducts for heating, air-conditioning, or exhaust systems. These
have oval, round or rectangular voids of varying size
members
systems.
can provide ducts or raceways for the various
which
in cores drilled in the field can provide access and
Openings
distribution. The voids in the slabs are aligned and connected
to provide continuity of the system.
Other
Sub-Systems
ceilings, crane rails, and other sub-systems can be
Suspended
items
accomodated with standard manufactured hardware
easily
and embedded plates as shown in F ig 55
Systems Building
As
more and more systems buildings are built with precast and
of
method
this
in
intrest
as
and
concrete,
prestressed
the
of
more
that
expect
can
we
increases,
construction
building sub-systems will be prefabricated and pre-coordinated
with the structure.
This leads to the conclusion that those parts of the structure
be
logically
should
skills
labor
most
the
require
that
The
field.
the
in
installation
to
prior
prefabricated
basic
of
preassemblies
be
can
components
prefabricated
systems or electrical/mechanical. To reduce on-site
plumbling
combination
or
units
bathroom
prefabricated
labor,
Fig
modules have been developed as shown in
bathroom/kitchen
Such units include bathroom fixtures, kitchen cabinets and
56
as well as wall, ceiling, and floor surfaces. Plumbing
sinks,
to
are often connected and assembled prior to delivery
units
molded
sites. These bathroom/kitchen modules can be
job
the
To
components.
drywall
from
fabricated
or
units
plastic
on
the
built
be
plant
can
module
the
floor,
double
a
eliminate
designed
be
or the walls of the unit can
member
structural
enough for all fixtures to be wall hung. In the latter
strong
the units are placed directly on a Drecast floor and in
case
with
are located in a stack f ashion
mult-story
construction
a
directly over the one below. A bloc k-out for
bathroom
one
are
conn ections
is
provided in the precast floor and
chase
made from each unit to the next to provide a verti cal plumbing
in
wet-wall plumbing systems, as shown
Prefabricated
stack.
Fig 57 , incorporate preassembled piping systems using snap-on
or no-hub connections made up of a variety of material s. These
flooring
prestressed
require a block-out in the
only
units
economy
and are also arranged in a stack fashion. Best
units
a
bathrooms are backed up to each other, since
when
results
bathrooms.
common vertical run can service two
Some
core
modules
not
only
feature
bath
and
kitchen
142
components, but also HVAC components all packaged in one unit.
prestressed
can also be easily accomodated in
modules
These
structural systems by placing them directly on the prestressed
members with shimming and grouting as required.
0 ;0-1..... 00
''.. 0
0 0
O.00-0-0Q .OD'
010QQQ
0
0
0
0
Fig.
55
143
Kitchen/bathroom modules can be pre-assembled on precast prestressed slabs
ready for installation in systems buildings
Fig.
56
144
Prefabricated wet-wall plumbing systems incorporate pre-assembled piping
Fig.
57
145
STRUCTURAL
FASTENER
High-Strength Bolts
by
designed
The
two
basic types of high-strength bolts are
hexagon-head
heavy
ASTM
and A490. These bolts are
as
A325
bolts,
used wi th heavy semifinished hexagon nuts, as shown in
in
bolts
58.
The threaded portion is shorter than for
Fig
A325
rolled.
and may be cut or
nonstructural
applications,
an
having
steel
medium carbon
heat-treated
bolts
are
of
on
depending
ksi
92
to
81
of
approximate
strength
yi eld
alloy
of
are
but
heat-treated
also
are
bolts
A490
diameter.
ksi
steel
having a n approximate yield strength of 115 to 130
depending also on diamater.
bo
High-strength
comm on
most
The
3/4
in. and 7/ 8
design are 3/4 i n
in.
from 1/2 to 11/2
range in diameter
Its
are
diameters used in building construction
bri dge
in., whereas the most common sizes in
. and 1 in.
High-strength bolts are tightened to develop tensile stress in
the
on
in a predictable clamping force
results
which
them
is
joint
a
through
loads
service
of
joint. The actual transfer
being
pieces
the
in
developed
due to the friction
therefore,
designed
are
containing high-strength bolts
Joints
joined.
ultimate
for
basis
the
is
slip
where
type,
friction
as
either
or as bearing type, where bearing of the bolt shank
strength;
against the hole is the basis for ultimate strength.
with
ca librated
bolts may be either
these
of
Instal lation
wrench
ordinary
wrenches, aaor more commonly with any
torque
Ives
invo
method
r
using the "turn-of-the-nut" method. The latte
the
from
starting
making an additional angular turn of the nut
snug position.
Ribbed Bolts
bolts of ordinary rivet steel which have a rounded head
These
and raised ribs paral lel to the shank were used for many years
given
alternative to rivets. The actual diameter of a
an
as
into
hole
the
than
larger
slightly
is
bolt
ribbed
of
size
bolt
the
bolt,
ribbed
In driving a
driven.
is
it
which
a
producing
hole
the edges around the
into
cuts
actually
particularly
was
bolt
This type of
fit.
tight
relatively
had
which
bearing connections and in connections
in
useful
stress reversals.
A modern variation of the ribbed bolt is the interference-body
shown in Fig 58 which is of A325 bolt steel and instead
bolt
wel I
longitudinal ribs has serrations aro und the shank as
of
around
serrations
the
of
Because
to the shank.
parral lel
as
an
called
often
the ribs, this bolt is
through
shank
the
146
bolt. Ribbed bolts are
interrupted-rib
bolt in the hole is desired and it
the
of turning the nut without the s
means
head as may be requried with
bolt
the
bolts.
A325
ordinary
Ttpes of
used when tight fit
permits tighten ing
multaneous hold ing
fitti
loose
smooth
of
by
of
ng
High-Strength Bolts
At the present time the two basic types of high strength bolts
A490,
the A325 bolt, for most common situations, and the
are
for use on higher strength steels where an excessive number of
is
bolt
A325
otherwise be required. The
might
bolts
A325
on
apart
degrees
120
by three radial lines spaced
iodentified
and
heads
Both types of bolts have heavy hexagon
head.
the
Another
nuts.
hexagon
semifinished
heavy
with
come
their
is
bolts
A325 and A490
the
both
of
characteristic
it
thread lengths, the shorter thread lengths making
shorter
to exclude the threads from the shearing plane. Figure
easier
and
A325
Table 9. show the control dimensions for
and
59.
A490 bolts and the methods of identification.
bolts
ASTM A490 bolts are substituted for A325
Occasional ly,
bolts
A490
longer thread dimension is required, the
a
when
standard
as
same hexagon head and thread length
the
having
A307 bolts but having the same strength as A325 bolts.
bearing
for
A
variation
of the standard A325 and A490 used
have a
bolts
These
olt.
b
interference-body
is
the
connections
high-strength
and may be used with the standard
head
button
type
interference-body
with self-locking nuts. The
or
nuts
bolts have particular applications wher e high bearing capacity
is desired together with stress reversa Is or vibratory loads.
Installation
Techniques
required
the
developing
general methods of
two
are
There
calibrated
One is called the
pretension indicated in Table ...
wrench method and the other the turn-of-the-nut method.
The calibrated wrench method includes the use o f manual torque
specific
power wrenches adjusted to stall at a
and
wrenches
of
amount
the
controlling
of
studies
Early
value.
torque
by
many
perf ormed
measurements were
torque
by
pretension
investigators including Stewart and Maney. Mane y reported that
variations in tensile stresses produced by a gi ven torque were
percent.
10
as +/- 30 percent with an verage of + /high
as
fie Id
by
this variation, which was also confi rmed
to
Due
Bolted
and
Rivet ed
on
Council
Research
the
experience,
calibrated
has recommended that torque or
Joints
Structural
in
be set to produce a bolt tension 5 to 10 percent
wrenches
excess of the value indicated in Table...
in the early 1950's and
Beginning
was
method
turn-of-the-nut
the
1960's
continuing into the
the
whereby
developed
147
High-strength
hexagon head bolt
High-strength interference-body bolt
Fig.
58
High-Strength Bolt Dimensions
Nut Dimensions. In.
Bolt Dimensions, In.
Nominal
bolt size.
D
Heavy Hex Structural Bolts
Height.
H
Width across
Bats F
Heavy Hex Nuts
Thread
length
%
%
%.
%"
116
0/6
1%f
%
I'/,
1/8
%/
1%.
/6
"/.
Is/
1%1l'.
2
1/,
11/
2./m
2%
1
"/.4
'w
2/3
'./Is
Fig.
1
%
1
"/
/
/,
1%.1
1%
1%/
11'%.
2
21/4
21/
31/4
11/.
1%/
2
Height.
H
Width across
flats W
"4/6.
"/.4
1%."
1%3
2
2
2%
1/32
1
' %3/
59
AISC- 1.23.5
IEqual to 70 percent of specified minimum tensile strengths of bolts, rounded off to the nearest
kip.
Table 9
148
specified
a
in the bolt is obtained by
force
pretensioning
which
position
nut from an initially snug
the
of
rotation
to
a specific amount of strain in the bolt. According
causes
Joints,
Structural
Bolted
and
Riveted
Research council on
the
nut is considered to be snug when impacting first begins as it
or
being tightened by an impact wrench. Although snugness
is
the
of
condition
the
to
due
vary
can
tightness
initial
surfaces being tightened, this variation is not significant.
inadequate
wonder whether there is danger of having
may
One
load;
proof
if the pretension exceeds the
strength
reserve
when it approaches 90 percent of the ultimate strength.
i.e.,
with
60 shows the effect of various turns of the nut
Figure
wrench
calibrated
the
safety indicated. If
of
margin
the
the
with
factor,
strength is the critical
used
is
method
of
possibility
The
shown in Fig 60
margin
safety
typical
a
considered
not
is
wrenches
overtorquing the bolts with power
bolts
the
fractures
usually
such overtorquing
since
problem
the
In
installation.
during
replaced
are
they
and
factor
critical
the
is
deformation
method,
turn-of-the-nut
either
For
typical safety margin shown in Fig 60.
the
with
turns
one can expect a minimum of 21/4
process
installation
from snug to fracture. When the turn-of-the-nut used and bolts
are tensioned using 1/8 turn increments, frequently as many as
The
fracture.
to
snug
from
obtained
be
may
turns
four
method is the cheapest, is more reliable, and
turn-of-the-nut
is generally the preferred method.
method requirements, as approved by AISC-1.23.5,are given
The
the Research Council 1966 specifications. The approved nut
by
rotations are indicated in Table 61
Friction-Type and Bearing -Type
Connections
1969 provides for two categories of high-strength bolted
AISC
in
Bolts
bearing-type.
and the
friction-type
the
joints,
either type of joint are installed by the same process so that
bolted
the
pretension is provided. Performance of
same
the
load
service
identical;
is
loads
service
under
joints
the
between
difference
The
friction.
by
is
transmission
friction-type and bearing-type connection lies entirely in the
factor of safety provided against slip under overloads.
higher
the
has
so called because it
is
friction-type
The
stress
when
suitable
thus
and
slip
safety against
of
factor
of
or cyclical loading may occur. The higher factor
reversal
safety provides good fatigue resistance.
not
is
is so named for use when it
joint
bearing-type
The
to
overload
occasional
under
occurs
slip
if
critical
deemed
hole.
the bolt shank into contact with the side of the
bring
by
transfered
is
the stress
loading,
subsequent
any
For
in combination with bearing on the plate. As long as
friction
once;
only
occur
will
slip
such
static
is
loading
the
149
thereafter the bolt is already bearing against the material
the side of the hole.
at
%Turn
60
Safety margin
for strength
(calibrated wrench
tensioning method)
50
.9.
~4a
40
30
0
20
10
0.05
0.20
0.15
0.10
Bolt elongation, inches
Fig.
0.25
60
Nut Rotation" from Snug Tight Condition (from Ref. 7)
Disposition of Outer Faces of Bolted Parts
Both faces normal to bolt axis, or one face
normal to axis and other face sloped not more than
I : 20 (bevel washer not used)
Bolt length b not exceeding
8 diameters or
8 inches
Bolt length bexceeding
8 diameters or
8 inches
Both faces sloped not more
than I : 20 from normal to bolt
axis (bevel washers not used)
For all length of bolts
3/4turn
2/3 turn
1/s turn
a Nut rotation is rotation relative to bolt regardless of the element (nut or bolt) being turned.
Tolerance on rotation: 30' over or under. For coarse thread heavy hex structural bolts of all sizes and
lengthband heavy hex semi-finished nuts.
Bolt length is measured from underside of head to extreme end of point.
Fig. 61
150
BI BL IOGRAPHY
151
Evans
Inc.,
Gerw ick,
Wiley &
Construction of Prestressed
Sons, Inc., 1971.
Concrete
of Prestressed Concrete
Structural
Analysis,
Magne I,
1954.
Prestressed
Rud.
Structu res,
in
Bechtold
Publishers,
& Sons,
Publications,
Architecture,
Ltd.,
Watson-Guphill
Parker, Simplified Design of Rei nforced Concrete, John
Sons Inc., 1976.
Institute, Architectural
Concrete
Precast
Precast Concrete Institute, 1973.
&
John W & Sons
Housing, John Wiley
Concrete, Concrete
Concrete
Precast
Morris,
Publications, 1978.
&3,
1,2
Intext Educational
Hollard, Nachman, Yackev,
Macsai,
Inc., 1976.
John
Concrete Structures,
Koncz, Manual of Precast Concrete, vol
Company, 1971.
Design
1955.
Hall,
Nostrand
Van
Engineering,
of
Handbook
Co., 1974.
Mc Cormac,
1975.
and
Bennett, Prestressed Concrete, Chapman
and
1958.
Fintel ,
Reinhold
Lin,
Inc.,
Concrete,
Prestressed
of
Theory
1963.
Chi
&
Biberstein,
Prentice-Hall, Inc.,
&
Drewett
Concrete, Knapp,
Reinforced
Prestressed
Billig,
Sons, Ltd., 1944.
Wiley &
Concrete,
Precast
Concrete Institute, Precast Concre te Institute Design
Precast
Concrete
Precast
Prestressed Concrete,
Precast
Handbook
Institute, 1978.
Sollenberger,
&
Preston
Graw-Hill Inc., 1967.
& Johnson,
Salmon
1971.
Inc.,
Large
Sebestyen,
Academy
Hungarian
Walley,
Steel
Modern
Prestressed
Concrete,
Structures, Harper & Row,
Panel
Buildings, Publishing
of Sciences, 1965
Mc
Publishers
House
Prestressed Concrete Design and Construction,
of
the
London:
152
Her Majesty's
The
Stationery Office,
following are manufacturers
1953.
published catalogs:
Flexicore
Northeast
Schokbeton
San-Ve I
Spancrete
153