DFRTVHJ

1. COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF ARCHITECTURE
COURSE: - APROPRIATE BUILDING TECHINOLOGY
COURSE CODE: - ARCH4262
PREPARED BY: -
NAME ID NO/11
1. CHALA TAGANGE 1808
2. ISSA NUGUSSE 18115
3. LALISA WAGARI 1819
ASSIGNMENT I
ADVISOR’S: - INST. ADUGNA T. [MSc]
SUB.DATE:- DEC 23, 2014
BULE HORA, ETHIOPIA

2. 1. Prefabrication history, necessity, aim, advantages, limitations, and its relevance to
Ethiopia.
Prefabrication history
-Prefabrication has been used since ancient times.
-For example, it is claimed that the world's oldest known engineered roadway,
the Sweet Track constructed in England around 3800 BC, employed
prefabricated timber sections brought to the site rather than assembled
on-site.
-The Crystal Palace, erected in London in 1851, was a highly visible example of iron
and glass prefabricated construction; it was followed on a smaller scale by Oxford
Rewley Road railway station.
"Loren" Iron House, at Old Gippstown in Moe, Australia.

3. CONTS;
Aims of Prefabrication and necessity
 The term “precast concrete” or “prefabricated concrete” is a
construction product produced by casting concrete in a
reusable mold or "form" which is then cured in a controlled
environment, transported to the construction site and lifted
into place.
 A prefabricated building is a type of building that consists of
several factory-built components or units that are
assembled on-site to complete the unit.
 To form light weight structure like from steel, timber….
 TO Speed up the constructions.
 For high rise building.
 Formwork is not needed in assembling.

4. CONTS
Advantages
 Moving partial assemblies from a factory often costs less
than moving pre-production resources to each site.
 Deploying resources on-site can add costs; prefabricating
assemblies can save costs by reducing on-site work.
 Factory tools - jigs, cranes, conveyors, etc. - can make
production faster and more precise.
 Factory tools - shake tables, hydraulic testers, etc. - can
offer added quality assurance.
 Consistent indoor environments of factories eliminate
most impacts of weather on production.

5. CONTS
 Cranes and reusable factory supports can allow shapes
and sequences without expensive on-site.
 Higher-precision factory tools can aid more controlled
movement of building heat and air, for lower energy
consumption and healthier buildings.
 Factory production can facilitate more optimal materials
usage, recycling, noise capture, dust capture, etc.
 Machine-mediated parts movement, and freedom from
wind and rain can improve construction safety.

6. CONTS
Disadvantages or limitations
 Transportation costs may be higher for voluminous
prefabricated sections (especially sections so big that they
constitute oversize loads requiring special signage, escort
vehicles, and temporary road closures) than for their
constituent materials, which can often be packed more densely
and are more likely to fit onto standard-sized vehicles.
 Large prefabricated sections may require heavy-duty cranes
and precision measurement and handling to place in position.

7. CONTS
Prefabricated relevance to Ethiopia
 Prefabricated Structure Manufacturers, Supplier in Ethiopia,
Prefabricated Structure in Ethiopia, Prefab Structures at best
price in Ethiopia.
 We have a wide range of prefabricating in Ethiopia products,
DTH also engaged in offering a unique range of Prefab
Structure in Ethiopia. It has hassle-free functioning, excellent
& high quality of précised designing which makes these PEB
very popular and demanding product in the market.
 DTH Manufacturing PBE products using the high-quality grade
of raw material as per the industrial industry standards &
need, these Prefabricated Structure in Ethiopia are available
in diverse specifications as per the client specific
requirements.

8. 2. Modern reinforced concrete framing, their advantages and
their construction detail.
 Reinforced concrete (RC) frames consist of horizontal elements
(beams) and vertical elements (columns) connected by rigid
joints.
 For a strong, ductile and durable construction the
reinforcement needs to have the following properties at least:
 High relative strength.
 High toleration of tensile strain.
 Good bond to the concrete, irrespective of pH, moisture,
and similar factors.
 Thermal compatibility, not causing unacceptable stresses
(such as expansion or contraction) in response to changing
temperatures.
 Durability in the concrete environment, irrespective of
corrosion or sustained stress.

9. CONTS
 Many different types of structures and components of
structures can be built using reinforced concrete
including slabs, walls, beams, columns, foundations, frames
and more.
 Reinforced concrete can be classified as precast or cast-in-place
concrete.
 Designing and implementing the most efficient floor system is
key to creating optimal building structures. Small changes in
the design of a floor system can have significant impact on
material costs, construction schedule, ultimate strength,
operating costs, occupancy levels and end use of a building.

10. CONTS
 Advantages of Reinforced Concrete framing
Strength. Reinforced concrete has very good strength in
tension as well as compression.
Economical
Versatility
Durability
Fire Resistance
Ductility
Seismic Resistance
Ease of Construction

11. CONTS
3. Brief discuss different types of wood used for construction
purpose in Ethiopia with their application.
 The most popular softwood types of lumber grown across the world
are:
– Pinewood
– Firewood
– Redwood lumber
– Cedar wood
– Hemlock wood - eastern and western
 The most popular hardwood types of lumber grown across the world
are:
– Balsa wood
– Oakwood
– Maple wood - hard and soft
– Walnut wood
– Ash wood
– Poplar wood

12. CONTS
Types of woods for constructions in the Ethiopia
with their application
 There are about 1,000 tree and shrub species in Ethiopia.
 Of these, about 360 indigenous and home-grown exotic tree
species can supply lumber for construction and manufacturing
furniture.
 Currently, there is rapid development of industrial, commercial
and residential buildings and high deficit between supply and
demand of wood and wood-based products in the country that
has led to importing of lumber with hard currency.

13. CONTS
Albizia grandibracteata Taub.
Description: deciduous trees up to 28 m high
with a diameter of 80 cm
Working Properties: works well with machines
and hand tools; tom grain, splinters, chip marks
and rarely raised grain (wooly grain) are
observed during planning; timber has got
medium resistance while crosscutting, resulting
in burned saw marks and with splintering
fibers; holds nails satisfactorily with slight
tendency to split; its screw holding ability is
very good and does not split if pre-bored.

14. CONTS
Albizia gummifera (F. Gmel.) C.A. Sm.
Family: Fabaceae/Legurninosae Common
• Working Properties: works well with machine and
hand tools, saws easily, planes well with a slight
tendency to toughness on quarter Commercial Timber
Species in Ethiopia boards and nails well.

15. CONTS
Albizia schintperiana Oliv.
• Family name; aceae/Leguminosae
• Description: trees up to 35 in high with 1.2 m diameter
• Mechanical Properties at 12% MC: bending strength - 82
N/mm’; modulus of elasticity - 9308 N/mm2; work to
maximum load - 0.0994 mmN/mm"’; work to total
fracture - 0.2042 mmN/mm3; compression parallel to the
grain - 41 N/mm2; impact resistance - 9301 Nm/m2; and
side hardness - 3310 N.
• Natural Durability: moderately resistant; durable.

16. CONTS
• EXTRA EXAMPLES
• Antiaris toxicaria Lesch.
• Alstonia boonei De Wild.
• Allophylus abyssinicus (Hochst.) Radlkofer
• Albizia schintperiana Oliv.

17. 4.Brief discuss different types of brick used for construction
purpose, constituents of good brick earth, and different types
of brick bonds with their applications.
Constituents of good brick earth
• Three basic types of brick are un-fired, fired, and chemically set
bricks.
• Each type is manufactured differently.
Mud brick- Unfired bricks, also known as mudbricks, are made
from a wet, clay-containing soil mixed with straw or similar
binders. They are air-dried until ready for use.
Fired brick- Raw bricks sun-drying before being fired
• Fired bricks are burned in a kiln which makes them durable.
Modern, fired, clay bricks are formed in one of three processes
– soft mud, dry press, or extruded.
• Depending on the country, either the extruded or soft mud
method is the most common, since they are the most
economical.

18. • Brick masonry is made with bricks bonded together with the
help of mortar.
• Sometimes, mud mortar can be used to construct temporary
sheds but for permanent structures mortar made of cement or
lime are used.
 Normally, bricks contain the following ingredients:
– Silica (sand) – 50% to 60% by weight
– Alumina (clay) – 20% to 30% by weight
– Lime – 2 to 5% by weight
– Iron oxide – ≤ 7% by weight
– Magnesia – less than 1% by weight

19. CONTS
1. Stretcher Bond / Running Bond
• his bond is very easy to lay, in fact, is one of the
simplest ones used today.
• Stretcher bond is suitable when walls of half
brick thickness need to be constructed.

20. CONTS
2. Header Bond
• A header is the shorter face of the brick.
• In header bond brick masonry all bricks are constructed in the
header course.
• In this bond, the overlap is performed corresponding to a half
width of the bricks.
• The three-quarter brickbats are utilized in alternative courses
as quoins. This bond is mainly used for the construction of one
brick thick walls.

21. CONTS
3. English Bond
• One of the most commonly utilized variations of brick bonds in
masonry works.
• This bond essentially comprises of alternating courses of
headers and stretchers.
• Headers are laid centered over the stretchers in the course
below and each alternate row is vertically aligned.

22. CONTS
4. Flemish Bond
• For this type of bond, each course is made up of alternate
headers and stretchers.
• Each header is centered on a stretcher above and below and
every alternate course begins with a header in the corner.

23. CONTS
5. Stack Bond
6. Dutch Bond
7. Common Bond / American Bond
8. Facing Bond
9. Diagonal Bond
10. Rat Trap Bond

24. 5.Distinguish between timber framing and RC framing, advantages of steel
framing over timber framing, and advantages of steel framing over RC
framing.
 The construction technique is in most cases the first item to
be evaluated, because it is the one factor that properly
materializes the proposed design and determines the
efficiency of the project in terms of time, costs, labor,
finishes and final quality.

25. CONTS
RC framing
The overall goal is to be able to design reinforced concrete
structures that are:
– Safe
– Economical
– Efficient
Reinforced concrete is one of the principal building materials
used in engineered structures because:
• Low cost
• Weathering and fire resistance
• Good compressive strength
• Formability all these criteria make concrete an attractive
material for wide range of structural applications such as
buildings, dams, reservoirs, tanks, etc.

26. CONTS
Timber framing is;-
• The Timber Frame system is a very widespread system in the
American territory.
• It has low energy consumption during processing, is made from
renewable sources and has a high resistance to loads.
• Most often, structural calculations are made to find the correct
dimensions of the wood profiles and position them to form a
square.

27. CONTS
Steel framing;-
• The Steel Frame system is widely distributed in European countries.
• It has been mass produced with specific dimensions and spacing to be
coupled with industrially produced profiles and joints
• As a quick and clean work, this system presents many advantages. Its
versatility stands out as it can be used in buildings of up to four stores and
in commercial projects.
• Another important point is the possibility of recycling steel.

28. CONTS
Speed of construction
• A timber frame for a building is much quicker to assemble
than a standard brick and mortar house.
• As they are assembled in a similar way to timber frames, the
process of putting up a steel frame should be just as quick, but
the process can become more drawn out as it takes more tools
and labour to attach each element together.
• On top of that, timber frames can be constructed by
carpenters, whereas a steel frame requires steel
fabricators to weld together the structure.

29. CONTS
Steel frame over timber framing
Environmental impact & sustainability
• Timber and steel both have benefits and drawbacks when it
comes to their environmental impact, so it’s important to
thoroughly consider your options before making a decision.
• Using a steel frame results in less deforestation than timber,
which relies on both forests and the destruction of natural
environments to make room for more plantations, however the
other side of this argument is that as the need for timber
increases, the demand for more forests also increases.
• This would benefit the environment in lowering CO2 levels in
the air, and encourage ethical and sustainable use of forests.

30. CONTS
 Steel is thought to produce less waste than timber as steel
frames are manufactured very precisely, whereas as timber is
a natural product, there are some imperfections that render
some of the wood unusable.
 Steel, however, is a very energy intensive to create, with the
production process leaving huge carbon footprints that are
damaging the environment.
 The upside of this is that steel is 100% recyclable, so after the
intensive creation process, the steel can be used and reused.
 Steel is Less scrap and waste (2% for steel vs. 20% for lumber).
 Steel not deteriorated inorganic - will not rot, or warp.

31. Steel framing over RC framing
• Steel frame construction Have the following advantages over RC
framing
Advantages
• High strength results in safer structures, less maintenance and slower
aging of structure.
• Not vulnerable to any type of fungi or organism.
• Less probability of foundation problems - less weight results in less
movement.
• Not vulnerable to termites.
• Less probability of damage in an earthquake.
• Highest strength-to-weight ratio.
• Non-combustible- does not burn and will not contribute fuel to the
spread of a fire.
• Dimensionally stable - does not expand or contract with moisture
content.
• Consistent material quality - produced in strict accordance with
national standards, no regional variations.

32. CONTS
• Lighter than other framing materials
• Easy material selection - no need to cull or sort.
• Straight walls.
• Square corners.
• Small punch list.
• More steel recycled in North America each year than
aluminum, plastic and glass combined - with the industry's
overall recycling rate of 64%.
• Every ton of steel recycled saves 2,500 pounds of iron ore.
• Through the basic oxygen furnace steel making process,
steel framing uses a minimum of 25% recycled steel.16
• Easy to install services such as water pipes etc. between dry
wall panels and also easy to remove and replace without
causing considerable damage

33. THE END
• THANK YOU FOR YOUR ATTENTIONS!