4.

Prefabrication and
Prefabricated Structures

Behailu Z. (Ph.D. Cand.)

 Prefabrication and Prefabricated Structures
Conceptual and Historical Overview
 21st century design technologies present us with endless
possibilities to ‘rethink’ how we design and manufacture
and:
 create a shift from mass-production to mass-
customization;
 embrace parametric modelling for site specific,
value driven responses;
 maximize the interface of these technologies
with manufacturing.
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
Conceptual and Historical Overview

 Social, economic and environmental factors suggest an

urgent need to consider new ways to build. These factors
include:
 shortages of skilled trade labour in many communities;
 need for increased construction quality and lower costs;
 need to improve construction productivity;
 need for more sustainable, cradle to cradle solutions;
 increased acceptance of quality prefabrication.

Behailu Z. (Ph.D. Cand.)

Prefabrication and Prefabricated Structures
Conceptual and Historical Overview

Prefabricated homes were produced during the Gold Rush in the United States, when
kits were produced to enable Californian prospectors to quickly construct accommodation

Prefabricated housing was popular during World War II due to the need for mass
accommodation for military personnel.

The world's first prefabricated, pre-cast panelled apartment blocks were pioneered in
Liverpool

Many buildings were designed with a five-ten year life span, but have far exceeded this,
with a number surviving today.
5
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
Conceptual and Historical Overview
What is prefabrication?
Prefabrication is the practice of assembling components of a structure in
a factory or other manufacturing site, and transporting complete assemblies or
sub-assemblies to the construction site where the structure is to be located.

 It is combination of good design with modern high performance components and

quality controlled manufacturing procedures.

This work is carried out in two stages, manufacturing of components in a place

other than final location and their erection in position.

6
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
Conceptual and Historical Overview
Prefabricated sections are produced in large quantities in a factory and then shipped to
various construction sites.

This procedure may allow work to continue despite poor weather conditions and should
reduce any waste in time and material at the site.

Precast concrete units are cast and hardened before being used for construction

Sometimes builders cast components at the building site and hoist them into place after
they harden.

This technique permits the speedy erection of structures.

7
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
Conceptual and Historical Overview

 The Prefabrication as defined will be done in two stages Manufacturing

at factory condition and erection of components at the required location.

 This requires certain stages of preparation. They are

a) Casting.

b) Curing.

c) Transportation and erection.

8
Behailu Z. (Ph.D. Cand.)
 Prefabrication and Prefabricated Structures
Conceptual and Historical Overview

a) Casting

Precast components are casted with

controlled cement concrete in moulds
of required shape and sizes.

The vibrator is used to vibrate

concrete and this removes any
honeycombing inside the components.

9
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
Conceptual and Historical Overview
b) Curing

After 24 hours of casting, the

casted components are released
from the mould and transported to
curing tanks. Certain special
components like railway sleepers
where high strength is required are
steam cured.

10
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
Conceptual and Historical Overview

c) Transportation and erection

After complete curing is done the

components are transported to the
site with heavy trucks and erection
will be done using cranes with
skilled labour force.

11
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
Conceptual and Historical Overview

Behailu Z. (Ph.D. Cand.)

Prefabrication and Prefabricated Structures
Precast Concrete Applications

 Precast concrete has several advantages, including:

Durability,
Ease of repair
Cost – effective,
High quality
Aesthetics

13
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
Precast Concrete Applications
Precast concrete has many applications, including:
Building components: fireplace mantels, cladding, trim, and curtain walls
Structural components: foundations, beams, floors, walls, and columns.
Building frames: structural frames, which are made up of precast concrete
columns, beams, and slabs.
Parking garages:
Water management:
Retaining walls:
Septic tanks:
14
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
Precast Concrete Applications

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Applications

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Applications

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Applications

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Applications

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Applications

Behailu Z. (Ph.D. Cand.)

Prefabrication and Prefabricated Structures
Precast Concrete Applications

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Applications

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Applications

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Applications

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

 Prefabrication and Prefabricated Structures
Precast Concrete Elements
What is Prestressed Concrete?
 Prestressed concrete is a type of concrete that is reinforced with steel to create
compressive stresses that counteract the tensile stresses that occur when the
concrete is used:
 Prestressed concrete is made by:
a) Stretching steel tendons to about 80% of their strength
b) Pouring concrete around the tendons into molds
c) Curing the concrete
d) Releasing the tendons, which causes them to try to return to their original length
Behailu Z. (Ph.D. Cand.) Modern Construction Techniques
Prefabrication and Prefabricated Structures
Precast Concrete Elements

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Elements
Prestressing Principle

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Elements
Precast Concrete

What is Precast Concrete?

 Concrete NOT cast in its final position in a structure.
 Can be cast off to the side of the structure.
 Most commonly refers to plant casting.
 Shipped by truck, barge, or rail.
 Requires crane at jobsite for erection.

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Elements
Precast Concrete

What Can Be Precast?

 Slab Elements
 Beams (& Girders)
 Columns
 Wall Panels
 Other

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Elements
Precast Concrete Frame Components

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Elements
Portal Frame Components

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
Precast Concrete Elements

Portal Frame Components

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS
Some of the prefabricated components are as explained below

a) Columns
 A column is a vertical member carrying the beam and floor loadings to the
foundation.

 It is a compression member and therefore the column connection is

required to be proper.

 The main principle involved in making column connections is to ensure

continuity and this can be achieved by a variety of methods.

33
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS
Some of the prefabricated components are as explained below

a) Columns
 A column is a vertical member carrying the beam and floor loadings to the
foundation.

 It is a compression member and therefore the column connection is

required to be proper.

 The main principle involved in making column connections is to ensure

continuity and this can be achieved by a variety of methods.

34
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Columns

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Columns

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS
Column to Column Connection

37
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

b) Beams
Beams can vary in their complexity of design and reinforcement
from the very simple beam formed over an isolated opening to the
more common encountered in frames where the beams transfer
their loadings to the column.

38
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS
b) Beams

Methods of connecting beams and columns are

A precasting concrete haunch is cast on to the column with a locating dowel or

stud bolt to fix the beam.

A projecting metal corbel is fixed to the column and the beam is bolted to the
corbel.

Column and beam reinforcement, generally in the form of hooks, are left exposed.
The two members are hooked together and covered with insitu concrete to
complete the joint.
39
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS
Beam to Beam Connection

40
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Beams and Girders

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Beams and Girders

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Beams and Girders

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Beams and Girders

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Beams and Girders

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Beams and Girders

Haunch Support for

Double Tee Member

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS
Beam to Column Connection

47
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS
Beam to Column Connection

48
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

c) Waffle unit for flooring / roofing

These are suitable for roofs / floors spanning in two directions.

They are laid in a grid pattern.

 These units are cast in moulds.

The saving achieved is not much. Also Shuttering are complicated and
costly.

Time consumption for construction is less

49
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

50
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Slab to Beam
Connection

51
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Slabs and Tees

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Wall Panels

 Wall panels available in standard 8’-0" widths.

 Can be flat, or have architectural features such as window and door
openings, ribs, reveals, textures, sandwich (insulation built-in),
sculptured, etc.

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Wall Panels

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Wall Panels

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Wall Panels

Behailu Z. (Ph.D. Cand.) Modern Construction Techniques

Prefabrication and Prefabricated Structures
PREFAB BUILDING COMPONENTS

Glance at building
process

57
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Connections and Joints
 Connections are sometimes called ‘joints’ — the terminology is loose and
often interposed.
 Connection: is the total construction between two (or more) connected
components, it includes a part of the precast component itself and may
comprise of several joints.
 Joint: is the part of a connection at individual boundaries between two
elements (the elements can be precast components, in situ concrete, mortar
bedding, mastic sealant, etc.)
Behailu Z. (Ph.D. Cand.)Modern Construction Techniques
Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS

Connections and Joints

 Engineers prove the capacity of the entire connection by

assessing the behavior of the individual joints.
 Structurally joints are required to transfer all types of forces
— the most common of these being compression and shear, but
also tension, bending and (occasionally torsion).

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Connections and Joints

Moment and Shear

transfer at a Corbel

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Connections and Joints
Weld Plates
 The most common method of connecting precast members
is use of steel weld plates.
 Typically, the precast members have embedded plates that
can be used as welding surfaces for loose connecting plates
or angles.
Behailu Z. (Ph.D. Cand.)Modern Construction Techniques
 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS

Connections
and Joints

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS

Connections and Joints

Rebar and Grout

 Used typically with slabs, reinforcing bars are
spliced into slabs and grouted in place.

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS

Connections
and Joints

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS

Connections
and Joints

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Column foundation connection

 Connections to foundations ,such as pad footing, pile caps,

retaining walls, ground beams etc are made in one of three types:
1) Base Plate
2) Grouted Pocket/sleeves

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Column foundation connection

Base Plate

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Column Base plate Connection Details
Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Column foundation connection

Base Plate

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Column foundation connection

Base Plate

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Column foundation connection

Grouted Pocket

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Column is Continuous Column is Discontinuous

Behailu Z. (Ph.D. Cand.)

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection
a) Type I (Vertical Member is Continuous), both in design and construction
terms) and horizontal elements are connected to it:
 Type I A Hidden connections, for which there is enormous range.
 Type I B Visible connections, such as deep corbels or nibs.
b) Type II (Vertical Member is discontinuous), only in construction terms) and
horizontal elements are either structurally continuous or separate across the
junction.
 Type II C the end of beams are simply supported and dowelled at the column
base.
 Type II D continuous beams are supported and dowelled at the column head.

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection
Type I (Vertical Member is Continuous),
Type I A Hidden connections, for which there is enormous range.

Billet Beam to Column

Hidden Connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection
Type I (Vertical Member is Continuous,
Type I A Hidden connections, for which there is enormous range.

Welled plate Beam to

Column Hidden Connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection
Type I (Vertical Member is Continuous,
Type I A Hidden connections, for which there is enormous range.

Cleat Beam to Column

Hidden Connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection
Type I (Vertical Member is Continuous,
Type I A Hidden connections, for which there is enormous range.

Sliding plate Beam to

Column Hidden Connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Sliding plate Beam to

Column Hidden Connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection
Type I (Vertical Member is Continuous,
Type I B Visible connections, such as deep corbels or nibs.

Shallow corbel Beam to

Column visible Connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection
Type I (Vertical Member is Continuous,
Type I B Visible connections, such as deep corbels or nibs.

Deep corbel Beam to

Column visible Connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection
Type I (Vertical Member is Continuous,
Type I B Visible connections, such as deep corbels or nibs.

Nib Beam to Column (or

Wall) visible Connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection
Type II (Vertical Member is discontinuous,
Type II C the end of beams are simply supported and dowelled at the column base.

Beam to Column
Head Connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection
Type II (Vertical Member is discontinuous,
Type II D continuous beams are supported and dowelled at the column head.

Continuous beam to
discontinuous
column connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Example –Beams,
Columns and Hollow
Core Slab

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS

Example –Wall Panels

and Double Tees

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS

Example –Wall Panels

and Double Tees

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS

Example –Mid-Rise
Bearing Panels
w/Precast Floor Planks

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS

Example –Mid-Rise Bearing

Panels w/Precast Floor Planks

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Beam – Column connection

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Misc. Concrete Anchors, Imbeds

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Misc. Concrete Anchors, Imbeds

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Ties in precast concrete structures

Locations of Ties in
precast skeletal structures

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Ties in precast concrete structures

Details and Locations

of horizontals floor
ties in precast floor

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

 Prefabrication and Prefabricated Structures
PRECAST CONCRETE CONNECTIONS
Ties in precast concrete structures

Continuity floor ties

in hollow core slabs

Behailu Z. (Ph.D. Cand.)Modern Construction Techniques

Prefabrication and Prefabricated Structures
ADVANTAGES AND DISADVANTAGES

Advantages:
Saving in cost, material, time & manpower.

Shuttering and scaffolding is not necessary.

Installation of building services and finishes can be done immediately.

Independent of weather condition.

Components produced at close supervision .so quality is good

104
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
ADVANTAGES AND DISADVANTAGES

Advantages:
Clean and dry work at site.

 Possibility of alterations and reuse

Correct shape and dimensions and sharp edges are maintained.

Very thin sections can be entirely precast with precision.

105
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
ADVANTAGES AND DISADVANTAGES
Disadvantages:
 Handling and transportation may cause breakages of members during
the transit and extra provision is to be made.

Difficulty in connecting precast units so as to produce same effect as

monolithic. This leads to non-monolithic construction.

They are to be exactly placed in position, otherwise the loads coming on

them are likely to get changed and the member may be affected.

106
Behailu Z. (Ph.D. Cand.)
Prefabrication and Prefabricated Structures
ADVANTAGES AND DISADVANTAGES

Disadvantages:
High transport cost

Need of erection equipment

Skilled labour and supervision is required.

107
Behailu Z. (Ph.D. Cand.)
End of Chapter 4

Behailu Z. (Ph.D. Cand.) 108

 Individual Assignment

1) Discuss the basic concepts and applications methods of

Construction Demolition and Dewatering

109
Behailu Z. (Ph.D. Cand.)