AR 493/ BUILDING TECHNOLOGY 5
ALTERNATIVE BUILDING CONSTRUCTION
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CAST IN PLACE CONCRETE AND
PRECAST CONCRETE
INSTRUCTOR:
AR. ROBINSON V. BERGANTIÑOS, uap
Cast in SITU Concrete
• Column, slab, etc. , elements
are cast on site and hence it is
difficult to control mix,
placement and curing
• Quality control and
maintenance are difficult
• Requires time in gaining
strength
• Increase in strength at SITU by
accelerated curing is difficult
Precast Concrete
• Elements are manufactured in
a controlled casting
environment and it is easier to
control mix, placement and
curing
• Quality can be controlled and
maintained easily
• Less labors are required
• Precast concrete construction
is quick as it can be installed
immediately and there is no
waiting for it to gain strength
I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
Floor System – it is defined as a
structural system consisting of both
the structural floor slab and any
beams supporting it.
A. Flat Slab
• The flat slab is a two-way
reinforced concrete slab that
usually does not have beams
and girders, and the loads are
transferred
directly
to
the
supporting concrete columns
• The thickness of the flat slab is
minimum 8” or 0.20m.
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I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
Advantages of Flat Slab:
1. It minimizes floor-to-floor heights
when there is no requirement for a
deep false ceiling. Building height
can be reduced
2. Automatic sprinkler is easier
3. Less construction time
Disadvantages of Flat Slab:
1. In flat slab system, it is not possible
to have large span
2. Not suitable for supporting brittle
(masonry) partitions
3. Higher slab thickness
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I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
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B. Flat Plate – a flat plate is a one-way or two-way system usually supported
directly on columns or load bearing walls. It is one of the most common
forms of construction of floors in buildings. The principal feature of the flat
plate floor is a uniform or near-uniform thickness with a flat soffit which
requires only simple formwork and I easy to construct.
Application:
• Short to medium spans with
light loading
• For LL=50 psi, 15’-30’ spans
Conditions:
• Architectural layout should
be well planned to fully
enhance the main area
where high flat ceiling with
nearly
arranged
steel/concrete columns are
required in the design
• Spacing of columns
• Punching shear checks at
column areas
• Long term deflection of the
flat plate
I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
Advantages of Flat Plate
• Simple formwork and suitable for
direct fix or sprayed ceiling
• No beams – simplifying under-floor
services
• Minimum structural depth and
reduced floor-to-floor height
Disadvantages of Flat Plate
• Medium spans
• Limited lateral load capacity as
part of a moment frame
• May need shear heads or shear
reinforcement at the columns or
larger columns for shear
• May not be suitable for heavy loads
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I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
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C. Ribbed Floor - consisting of equally spaced ribs that are usually
supported directly by columns. They are either one-way spanning systems
known as ribbed slab or a two-way ribbed system known as a waffle slab.
Types of Ribbed Slab:
One-way Ribbed Slab – a one-way slab
consists of a series of small reinforced
concrete T-beams that are connected
with girders that in turn carried by the
building column
Two-way Ribbed Slab/Waffle slab – this
type of slab was designed to decrease
the weight of traditional full-concrete
slabs. It is also known as waffle slab
because they look like waffles with rows
of beams running underneath them.
I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
Advantages of Ribbed Slab:
• Savings on weight and materials
• Long spans
• Attractive soffit appearance if
exposed
• Economical
when
reusable
formwork pans will be used
• Vertical penetrations between ribs
are easy
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Disadvantages of Ribbed Slab:
• Depth of slab between the ribs
may control the fire rating
• Requires special or proprietary
formwork
• Greater floor-to-floor height
• Large vertical penetrations are
more difficult to handle
D. Waffle Slab – is a reinforced concrete roof or flooring containing square
grids with deep sides and it is also called as grid slabs
Waffle Slab Usage:
• Can be used as both ceiling and floor slab
• The concrete waffle slab is often used for industrial and commercial
buildings while wood and metal waffle slabs are used in many other
construction sites
I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
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Characteristics of Waffle Slab:
• Suitable for flat areas
• The reinforcement in the waffle slab is provided in the form of mesh or individual bars
• The thickness of waffle slab recommended is 85 to 100mm while the overall depth of slab is
limited to 300 to 600mm
• The width of beams or ribs provided in waffle slab are generally 110 to 200mm
• Waffle slab requires only 70% of concrete and 80% of steel from the concrete and steel
used for stiffened raft
I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
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Advantages of Waffle Slab
• Used for larger span slabs or floors and used when there is limited requirement for number
of columns
• Good structural stability along with aesthetic appearance
• Can be made of concrete or wood or steel
• Good vibration control capacity, useful for public buildings to control vibrations created by
movements of crowd
• Lightweight and requires less amount of concrete
• Several services like lighting, plumbing pipes, electrical wiring, air conditioning, insulation
materials etc. can be provided
Disadvantages of Waffle Slab
• Formwork tools required are very costly because of large quantity requirement of pods and
some special tools
• The floor height should be more hence number of floors is reduced
• The services provided in the waffle arrangement without proper maintenance may cause
damages to the slab
• Skilled workers are required during its construction
• They are not suitable for sloped areas. If there is slope area, the area must be levelled with
filling or by excavating.
• They are not suitable against high winds or cyclonic areas because of their light weight
I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
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E. Lift Slab – a method of constructing concrete buildings by casting the floor or
roof slab on top of the previous slab and then raising (jacking) the slab with
hydraulic jacks.
I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
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Lift Slab System Limitation:
• This method shall not be used for multi-storey building, only used for 15-16 storey
building. No large span slab is constructed in this type of construction
• Hydraulic jacks has positive safety device on it
• Can lift only on slabs loaded up to 100,000 pounds at speeds of up to 14ft. An
hour
NOTE: (See video presentation)
F. Slip Form System – it is a method for building large towers or bridges from
concrete. The name refers to the “moving form” the concrete is poured into, which
moves along the project as the previously poured concrete hardens behind it. The
technique has also been applied to road construction.
Types of Slip Form System:
1. Vertical Slip form
The concrete form maybe surrounded by a platform on which workers
stand, placing steel reinforcing rods into the concrete and ensuring a smooth pour.
Together, the concrete form and working platform are raised by means of
hydraulic jacks.
I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
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I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
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I. FLOOR SYSTEM AND ROOF SLAB SYSTEM
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2. Horizontal Slip Form - same thing with the vertical, together, the concrete
form and working platform are moved horizontally by means of hydraulic jacks.
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II. WALL PANEL SYSTEM
Wall Panel – is a single piece of material, usually flat and cut into a rectangular
shape, that serves as the visible and exposed covering for a wall. Wall panels
are functional as well as decorative, providing insulation and sound proofing,
combined with uniformity of appearance, along with some measure of
durability or ease of replacement.
A. Flat Type Wall System
Advantages:
Disadvantages:
• Cost saving
• Decorative functions
• No more mold
• Insulating functions
• Extra time
• Soundproofing functions
• An end to touch cleaning
• Uniformity of appearance
• Watertight guarantee
• Durability
• Ease Replace ability
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II. WALL PANEL SYSTEM
Features and Benefits
• Special interlocking joint design allows
panels to easily lock into for faster
installation
• Can be combined with other Butler wall
systems,
bricks,
glass
and
other
conventional materials
• 16” panel width, combined with the side
“return leg” enables application of almost
any conventional finish on the interior of the
wall system
• Factory-installed rigid insulation board for
enhanced energy efficiency
• Available
colors
in several
visually
appealing
Applications:
Low and Mid-rise offices, Convention centers,
Performing Arts centers, Arenas, Airport
terminal Buildings, Schools and Universities,
and Hospitals
II. WALL PANEL SYSTEM
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B. Ribbed Type
It is the most economical wall system. In fact, this wall system is more
economical that wood, concrete or masonry alternatives.
Different types of Ribbed type wall panel:
WALL RIB
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II. WALL PANEL SYSTEM
TECH FOUR WALL PANEL
THERMAL CLAD REVEAL PANEL
II. WALL PANEL SYSTEM
Advantages:
• Inexpensive
• Much variation in styles
• Unlimited variation in color
though 10 to 40 options are
widely available
• It is fire resistant, mold and insect
resistant
• Eco-friendly
–
material
is
recyclable, and does offer cool
roof benefit
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Disadvantages:
• Fasteners are generally exposed,
which means maintenance/repair
every decade or so
• As caulking is likely used to seal
any gaps between panels, that is
additional maintenance concern
• Metal can dent or be scratched,
which is another item of concern
or reason to inspect the roof no
more than every 5 years
C. Wall Type – a curtain wall system consisting of performed metal cut stone,
precast concrete or panelized brick wall units, which may be pre-glazed or glazed
after installation. The framing is attached to the building structure and does not
carry the floor or roof loads of the building. The wind and gravity loads of the
curtain wall are transferred to the building structure, typically at the floor line.
II. WALL PANEL SYSTEM
elevation
Wall Type Benefits
• Lightweight
• Economical
• Easy installation
• Faster
• Wide range of product design
• Comprehensive wall panel
Characteristics
• Factory assembled
• Typical units are five to six feet
wide
• Fast and
process
easy
installation
plan
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II. WALL PANEL SYSTEM
Advantages:
If installed correctly curtain wall
systems
provide
excellent
structural integrity, as there are
fewer mullions and joints required
when compared to most window
wall systems. Also, because it acts
as a single unit, a curtain wall is
highly resistant to moisture, wind,
heat and earthquakes. Curtain
walls require little maintenance,
however improper installation may
lead to costly issues
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Disadvantages:
The additional cost of a curtain wall
system (which is often double or
triple, the cost of a window wall)
doesn’t eliminate issues such as
potential
damage
during
transportation or misalignment during
installation.
Another
reported
disadvantage of curtain wall systems
is noise transmission. Because there is
no true separation of floors, sound
travels between levels more freely
than with a window wall system.
D. Window Type Wall Panel – It is achieved by placing glazing between a
building’s concrete slabs, using the slabs as structural support. Window walls
have a break between the glass, with slab covers used to conceal the
concrete.
II. WALL PANEL SYSTEM
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There are either one-storey in height and made as wise as possible, or cast
narrower to span vertically for 2-3 floors
II. WALL PANEL SYSTEM
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II. WALL PANEL SYSTEM
Advantages:
Disadvantages:
Aside from advantages such as
customizability, ease of installation
and cost savings, window walls
require less engineering and safety
considerations as the exterior wall
is broken up by each floors’
concrete slab, providing built-in
fire stopping. Also, because the
separation of each window wall
unit creates a sealed space there
is less noise transfer and energy
loss. Further, if a unit becomes
damaged and needs repair that
specific unit can be removed and
replaced without affecting the
adjoining units.
Even with their many positives,
window wall systems do have
potential drawbacks. Because of the
break between the floors, window
wall systems often have a less
continuous look than curtain wall
systems. However, advancements in
design have solved this issue with
slab
covers.
Also,
more
considerations and planning need to
occur before installation in order for
thermal, air and water performance
to meet or exceed those of curtain
wall systems.
II. WALL PANEL SYSTEM
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E. Tilt Up Wall Sytem – It is a technique of site casting concrete walls or elements,
typically done on a horizontal surface and once cured, it is tilted vertically into
place using a mobile crane. It is temporarily braced into its final standing
position and is tied to the building’s roof and flooring system.
The term ‘’tilt-up’’ was coined in the late 1940’s to describe a method for
constructing concrete walls rapidly and economically without the form work
necessary for poured-in-place walls.
II. WALL PANEL SYSTEM
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Advantages:
1.
Economy. In areas where tilt-up design and construction expertise is available –
particularly a trained crane and rigging crew.
2.
Speed of construction. From the time the floor slab is placed, the typical elapsed time
from starting to form the panels until the building shell is completed is four to five weeks.
3.
Durability. Tilt-up buildings constructed in the late 1940s show little sign of age (except
architectural styling) and some are being handsomely remodeled.
4.
Fire resistance. Concrete is an obvious first choice for fire resistance. A 6½-in.-thick wall,
for example, has a four-hour fire rating.
Disadvantages:
1.
Not ideal for complex buildings. Generally a building being used for commercial or
industrial uses isn’t going to be very complex, which is why tilt-up walls work so well. This
method is perfect for large, rectangular buildings or structures.
2.
Difficult to work with on some worksites. A big difference between tilt-up and precast
walls is that tilt-up walls are fabricated right on the worksite.
3.
Lacking in versatility. Though tilt-up walls are somewhat versatile when it comes to large
buildings, they aren’t the best idea for smaller projects. Typically using tilt-up is only good
for a minimum size of about 5,000 square feet.
II. WALL PANEL SYSTEM
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II. WALL PANEL SYSTEM
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