case study about residential, the case stud y is divided into tow there are; local case study and international case study.

1. Bule Hora University
College of Engineering and Technology
Department of Architecture
Course name: Building Materials and Construction II
Course Code: ARCH2162
Individual Assignment
Name: - Amanuel Jilo
ID No: - 3232/14

2. 1. What do you understand by structural system of a building?
The structural system of a building refers to the arrangement and
configuration of the load-bearing elements that provide support and
stability to the structure. It is the framework that transfers the loads
acting on the building to the ground safely and efficiently. The structural
system is a critical aspect of building design and plays a significant role
in ensuring the overall strength, stability, and durability of the structure.
There are various types of structural systems used in building
construction, and the choice depends on factors such as the building's
size, purpose, location, architectural design, and the materials available.
Here are some common types of structural systems:
 Framed Structural System: This is one of the most common types of
structural systems, where the load-bearing elements consist of
columns, beams, and floor systems. The frame provides vertical
support, while the floor system transfers load horizontally to the
columns and beams.
 Load-Bearing Wall System: In this system, the load-bearing walls of
the structure carry the vertical loads and also provide lateral stability.
The walls act as both structural elements and partitions, supporting
the floors and roof.
 Truss System: Trusses are structural frameworks made of
interconnected beams and are often used in roofs and bridges. They
efficiently transfer the loads by distributing them along the members,
which can be made of wood, steel, or other materials.
 Shell System: Shell structures are curved or domed surfaces that
derive their strength from their shape. Examples include vaulted
roofs, domes, and thin-shell concrete structures. The load is
distributed across the entire surface, resulting in efficient load
transfer.

3.  Suspended Structural System: This system involves suspending the
load-bearing elements from cables or other supports. It is commonly
used in bridge construction and large-span structures like stadiums
and exhibition halls.
 Combined Structural System: Many buildings use a combination of
different structural systems to optimize load-bearing efficiency and
architectural design. For example, a high-rise building may have a
reinforced concrete core for vertical support combined with a steel
frame for lateral stability.
The selection of a suitable structural system depends on various factors,
including the intended use of the building, architectural requirements,
construction materials, site conditions, and cost considerations.
Structural engineers analyze these factors and design the structural
system to ensure that the building can withstand the anticipated loads
and environmental forces while meeting the required safety standards.
2. What are the different loads and environmental forces acting on
structural systems?
In structural engineering, loads and environmental forces refer to the
various external factors that act on a structural system. These forces can
have a significant impact on the stability, strength, and durability of the
structure. Here are some common types of loads and environmental
forces:
 Dead Load: This refers to the weight of the structure itself and any
permanent fixtures or components. Examples include the weight of
walls, floors, roofs, and structural elements. Dead loads are
constant and do not change over time.
 Live Load: Also known as imposed loads, live loads are temporary
and variable forces that act on the structure. They include the
weight of people, furniture, vehicles, and other movable objects.

4. Live loads can vary in magnitude and location, depending on the
intended use of the structure.
 Snow Load: Snow load is the weight of snow accumulation on
roofs, structures, and surfaces. It is particularly important in areas
with cold climates where snowfall can be significant. The design
of structures in these regions must account for the additional load
imposed by snow.
 Wind Load: Wind load refers to the force exerted by wind on the
structure. It can cause lateral forces that induce stress and
deflection. Wind loads are influenced by factors such as wind
speed, direction, and the shape of the structure. They are crucial in
the design of tall buildings, bridges, and other structures exposed
to wind.
 Seismic Load: Seismic loads are caused by earthquakes and
represent the ground motion forces that act on the structure. These
forces can cause significant damage and require careful
consideration in the design of structures located in seismically
active regions.
 Thermal Load: Thermal loads result from temperature variations
and the resulting expansion and contraction of materials.
Temperature changes can induce stress and movement in
structures, especially in materials with different coefficients of
thermal expansion.
 Soil Load: Soil load refers to the pressure exerted by the ground on
the foundation of a structure. It depends on factors such as soil
type, moisture content, and the weight of the structure. Soil loads
are important in the design of foundations, retaining walls, and
other structures in contact with the ground.
It is essential for structural engineers to consider these loads and
environmental forces during the design process to ensure the safety and
stability of the structure throughout its intended lifespan.

5. 3. Discuss the conditions for selection of structural systems. When
selecting structural systems for buildings such as the ones listed,
several factors need to be considered:
 Building function: The structural system must be able to support
the specific functions of the building. For example, the Ethiopian
Airlines Aviation Academy may require a different structural
system than the Hilton Hotel due to the different uses of the
buildings.
 Local building codes and regulations: The structural system must
comply with local building codes and regulations to ensure the
safety and stability of the building.
 Environmental conditions: The structural system should be able to
withstand the environmental conditions of the location, such as
seismic activity, wind loads, and soil conditions.
 Architectural design: The structural system should complement the
architectural design of the building and allow for the desired
aesthetic features.
 Construction materials availability: The availability of construction
materials in the local area may influence the selection of the
structural system.
 Cost: The cost of the structural system, including construction,
maintenance, and long-term durability, should be considered in the
selection process.
 Future expansion and flexibility: The structural system should
allow for future expansion or renovation of the building if needed.
 Sustainability: Consideration should be given to the environmental
impact and sustainability of the chosen structural system.
Overall, the selection of a structural system for these buildings will
require careful consideration of various technical, economic, and
aesthetic factors to ensure a successful and functional design.

6. 4. Briefly discuss the advantage and disadvantages of concrete, steel,
timber and precast concrete structures.
Here are the advantages and disadvantages of concrete, steel, timber, and
precast concrete structures:
Concrete Structures:
Advantages:
 High Compressive Strength: Concrete has excellent compressive
strength, making it suitable for supporting heavy loads and
resisting compression forces.
 Fire Resistance: Concrete is inherently fire-resistant, providing
passive fire protection to the structure.
 Durability: Concrete structures have a long lifespan and require
minimal maintenance when properly designed and constructed.
 Versatility in Design: Concrete can be molded into various shapes
and sizes, allowing for flexibility in architectural design.
Disadvantages:
 Low Tensile Strength: Concrete has low tensile strength, making it
susceptible to cracking under tensile forces. Reinforcement is
typically used to overcome this limitation.
 Heavyweight: Concrete structures are heavy, requiring substantial
foundations and potentially limiting their use in certain soil
conditions.
 Construction Time: Concrete structures often require more time to
construct compared to other materials due to curing and drying
times.
 Environmental Impact: The production of cement, a key
component of concrete, contributes to carbon emissions and
environmental degradation.
Steel Structures:

7. Advantages:
 High Strength-to-Weight Ratio: Steel has a high strength-to-weight
ratio, allowing for lighter structures and more design flexibility.
 Ductility: Steel structures have excellent ductility, enabling them to
withstand dynamic forces such as earthquakes and wind loads.
 Speed of Construction: Steel structures can be prefabricated off-
site, reducing construction time and costs.
 Recyclability: Steel is a highly recyclable material, making it
environmentally sustainable.
Disadvantages:
 Susceptible to Corrosion: Steel is prone to corrosion when exposed
to moisture and requires protective coatings to prevent rusting.
 High Cost: Steel structures can be more expensive than other
materials due to the cost of steel fabrication and installation.
 Thermal Conductivity: Steel has high thermal conductivity, leading
to potential heat loss in cold climates and heat gain in hot climates
without proper insulation.
 Fire Resistance: While steel is inherently fire-resistant, it can lose
strength and deform under high temperatures.
Timber Structures:
Advantages:
 Sustainability: Timber is a renewable resource and has a lower
carbon footprint compared to other materials.
 Thermal Insulation: Timber has excellent thermal insulation
properties, reducing energy consumption for heating and cooling.
 Aesthetics: Timber structures offer a natural and warm aesthetic
appeal.
 Ease of Construction: Timber is lightweight and can be easily cut,
shaped, and assembled, leading to faster construction.

8. Disadvantages:
 Susceptible to Moisture and Insect Damage: Timber structures
require proper moisture protection and treatment to prevent rotting
and insect infestation.
 Limited Span Length: Timber beams and columns have limitations
in span length compared to steel and concrete.
 Fire Risk: Timber is combustible, and fire resistance measures
need to be implemented to ensure safety.
 Maintenance: Timber structures require regular maintenance,
including sealing, staining, and repairs, to ensure longevity.
Precast Concrete Structures:
Advantages:
 Quality Control: Precast concrete elements are manufactured in
controlled environments, ensuring high-quality production.
 Faster Construction: Precast elements can be produced off-site
concurrently with on-site preparation, reducing construction time.
 Cost-Efficiency: Precast concrete structures can be cost-effective
due to reduced labor and on-site construction time.
 Durability: Precast concrete elements are durable and require
minimal maintenance.
Disadvantages:
 Transportation Challenges: The size and weight of precast
elements may require specialized transportation and handling
equipment.
 Limited Flexibility: Changes in design or modifications during
construction can be challenging with precast elements.
 Connection Design: Precast elements require careful consideration
of connection details to ensure structural integrity.
 Design Constraints: The design of precast elements may be limited
by size, shape, and manufacturing capabilities.

9. It's important to note that the advantages and disadvantages mentioned
above are general and can vary depending on specific project
requirements, design considerations, and regional factors.
5. Concrete structures are widely used in our country for several
reasons:
 Durability: Concrete structures are known for their long-lasting
durability, making them a popular choice for buildings and
infrastructure projects.
 Strength: Concrete has high compressive strength, making it
suitable for supporting heavy loads and withstanding forces such
as wind and earthquakes.
 Fire resistance: Concrete is non-combustible and provides
excellent fire resistance, making it a safe choice for buildings.
 Versatility: Concrete can be molded into various shapes and
sizes, allowing for flexible design options in construction
projects.
 Cost-effectiveness: Concrete is a relatively affordable building
material, making it a cost-effective choice for construction
projects.
 Sustainability: Concrete is made from natural materials such as
limestone, water, and sand, making it an environmentally
friendly choice for construction.
 Low maintenance: Once constructed, concrete structures require
minimal maintenance, reducing long-term costs for building
owners.
Overall, the combination of durability, strength, fire resistance,
versatility, cost-effectiveness, sustainability, and low Advantages of shell
and dome structures:
6. What are the advantages and disadvantages of shell and dome
structures?

10.  Strength: Shell and dome structures are known for their
strength and ability to withstand heavy loads, making them
suitable for large spans without the need for internal supports.
 Aesthetics: Shell and dome structures have a unique and
visually appealing design, making them popular for
architectural landmarks and iconic buildings.
 Space efficiency: These structures provide a large open space
without the need for columns or walls, making them ideal for
sports arenas, exhibition halls, and other large venues.
 Resistance to natural forces: Shell and dome structures are
often more resistant to natural forces such as wind and
earthquakes due to their curved and continuous form.
 Disadvantages of shell and dome structures:
 Cost: The construction of shell and dome structures can be
expensive due to the complex formwork and specialized
construction techniques required.
 Limited flexibility: The unique shape of shell and dome
structures can limit the flexibility in interior layout and design
compared to traditional rectangular buildings.
 Maintenance: The maintenance and repair of shell and dome
structures can be challenging due to the complexity of the
curved surfaces and the need for specialized expertise.
 Construction challenges: The construction of shell and dome
structures requires skilled labor and specialized construction
methods, which can pose challenges in terms of availability and
cost.
Overall, while shell and dome structures offer strength, aesthetics, space
efficiency, and resistance to natural forces, they also come with
drawbacks such as cost, limited flexibility, maintenance challenges, and
construction difficulties. maintenance make concrete structures the most
widely used structural systems in our country.

11. 7. List the different buildings in Ethiopia which were constructed using
precast concrete structural system.
 African Union Conference Center and Office Complex, Addis
Ababa
 Addis Ababa City Hall
 Addis Ababa City Hall

12.  Addis Ababa University College of Business and Economics
 Commercial Bank of Ethiopia Headquarters, Addis Ababa

13.  Ethiopian Airlines Aviation Academy, Addis Ababa
 Hilton Hotel, Addis Ababa

14.  National Bank of Ethiopia Headquarters, Addis Ababa
 United Nations Economic Commission for Africa (UNECA)
Conference Center, Addis Ababa.

15. 8. List the different buildings in Ethiopia which comprises of shell and
dome structures.
 African Union Conference Center and Office Complex,
Addis Ababa
 Addis Ababa City Hall
 Commercial Bank of Ethiopia Headquarters, Addis Ababa
 Ethiopian Airlines Aviation Academy, Addis Ababa
 Hilton Hotel, Addis Ababa
 United Nations Economic Commission for Africa (UNECA)
Conference Center, Addis Ababa
Summary
The selection of building materials and construction methods is a crucial
aspect of the design and construction process for any building. Factors
such as building function, local building codes, environmental
conditions, architectural design, material availability, cost, future
expansion, and sustainability all play a role in determining the most
suitable materials and construction techniques.
Building materials such as steel, concrete, wood, and masonry each have
their own advantages and limitations, and the choice of material will
depend on the specific requirements of the project. Additionally,
construction methods such as traditional masonry construction, steel
frame construction, or pre-engineered building systems may be selected
based on factors such as cost, speed of construction, and architectural
design considerations.
Ultimately, the selection of building materials and construction methods
should be carefully considered to ensure the safety, functionality,
durability, and aesthetic appeal of the building while also taking into
account environmental impact and long-term sustainability.