AGE 409
INTRODUCTION TO AGRICULTURAL
STRUCTURES DESIGNS. (3 Units)
Three Hours per week
Course Lecturers:
Coordinator: Prof. E.B. Lucas
Engr. P.O.O. Dada
Email dadafemo@yahoo.com
Office location: COLENG BUILDING

 Introduction to agricultural structures.
 Selection of materials in relation to use – steel, wood, concrete and masonry.
 Types of structural frames.
 Estimating loads,
 stress analysis.
 Introduction to structural design.- philosophy of design
 elastic and plastic design concepts.
 Reinforced concrete design.
 Design for axial loadings.
 Design of beams, foundation, slab, columns, connections and joints.
 Computer concept for improved analysis and design.
 Design project.

 A compulsory course for all student in the
Department of Agriculture Engineering .
Students are expected to participate in all the course activities and have minimum of
75% attendance to be able to write the final examination.
 They should also participate fully in all practicals.

 Agricultural buildings and Structures by
J.H. Whitaker.
 Farm structures in tropical climates by L.P. bengtsson FAO.

Three phases are recognized in a structure on Engineering project. They include:
Planning
factors affecting the layouts and dimensions
-- answer basic questions
-- aesthetics
- sociological, legal, economic and environmental
- construction requirement affecting type of structure to be selected
Designconsideration of alternative solution involved in planning phase
- choice dependent on economic and constructional features
- aspects of competitive bidding.
Constructionprocurement of materials, equipment and personnel
fabrication of members and sub-members
- transportation to site
- field construction and erection

 Beams and Columns
 Truss
 Arches
 Rigid frames
 Cylindrical tank
 Retaining wall

 Hinge support
 Roller support
 Free end or movable roller support
 Hinged immovable or fixed end support
 Built-in end support

 Types of loads:
 Dead loads – stationary
 Live loads – moving
Stress = F/A
Strain = Extension/length
Factor of safety (N) = ultimate stress/ design stress

Livestock Structures:
A facility primarily designed and constructed or remodeled to house animals with the overall aim of increasing productivity.
Livestock:
Domesticated animals kept under human control. Examples include:
Dairy cattle, pigs, sheep, goats, horses and poultry
Objectives of keeping Livestock
Food supply source
Raw materials
Manure supply
Transportation
Religion and culture
Social aspects
Sport and recreation
Employment and income

 Benefits of Livestock Structures
 Reduction of drudgery
 Protection for animals
 Individual and national benefits
 Environmental factors affecting animal performance
 Temperature
 Relative Humidity
 Ventilation
 Light
 Heat and Moisture

 Poultry, cattle and swine:
 Poultry:
Site selection : The site must be well drained and be in a good location.
It must be near to sources of adequate water which must be in good quality and quantity.
Ventilation must be adequate and protected from strong winds
Provision of foot-dips at entrances, wire netting and trenches where applicable
Disease control must be achieved by good sanitation and medical facilities.
Construction details :
The poultry house must be aligned in the east-west direction.
Floors may be made from gravel or well drained soil or concrete
Roofing materials can include corrugated metal sheets (cheap, durable)
Construction should be in done to aid sanitation and proper disposal of waste, dead birds etc.

 Shed and yards
 Battery cage
 Barns
 Hen basket
 Deep litter house

Crop Storage Structures: Container or unit designed and fabricated to perform the function of safely keeping crops
Justification of crop storage
• Seasonal variation
• Seeds for next planting season
• Economic considerations
• To avoid social unrest
• Protection from deterioration
Classification of Crop Storage Structure
• Improvised (indirectly used) eg. Baskets, earthen pots, drums, calabashes.
• Traditional (Indigenous) eg underground pits, rhumbu, platforms, ,cribs and poles.
• Modern (results of research) eg. Silos, warehouse, evaporative coolers

Technical Aspects of silos:
Silos can be classified into deep and shallow and this is done on the basis of the following: a) Plane of rupture method b) Equivalent diameter method c) Height to lateral dimension method
Pressure in silos:
Rankine’s equation:
L

1
 sin
1
 sin


 wy tan
2
( 45


2

Ventilation : circulation of air between an enclosure and it’s surroundings. It could be free (natural) or forced (mechanical means).
Factors to consider when designing for good ventilation include:
 Amount of heat and moisture generated
 Amount of heat and moisture to be exchanged

Amount of air required to achieve the above
 Method of supply and desired quantity of air to introduce.
Natural ventilation V= AES
V is Volume of air flow (m2/s)
A is area of inlet opening
E is effectiveness of opening (0.35-1.0 for perpedicular winds and 0.4-0.6 for diagonal winds
S is wind velocity (m/s)

Temperature of an enclosure is a reflection of the amount of heat present in the enclosure.
Heat may be added or removed and air is the medium of exchange.

Qt
Mn ho
 hi
Mn = mass of dry air(Kg/hr) hi = Enthalpy of incoming air as ambient temp. (KJ/kg of dry air) ho = Enthalpy of out going air at conditions inside the enclosure(KJ/kg of dry air)
Heat exchange is a function of the insulating value of the building components while moisture exchange depends on vapour permeability.

A beam is a structural member used to resist load acting across its longitudinal axis
It is designed to resist:
1.
Bending moment
2.
Transverse/Vertical shearing forces
3.
Deflection
Could be wooden, steel or concrete beams.
Design of wooden beams should take the following into consideration:
 Bending/ shear stresses
 Deflection
 Prevention of lateral buckling d/b < 3 for lateral stability and position of centriod

Deflection
A deformation that accompanies the bending of a beam
Bending deflection
Shearing deflection
Deflection of beam is dependent on:
 Type of loading
 Supports
 Span
 Modulus of elasticity of material of construction
 Maximum deflection 5 WL
4 b

384 EI where W = load per unit length
L = Span
E = modulus of elasticity

Design of Steel beams
Involves the following steps:
 Estimation of load to be sustained
 Compute the maximum bending moment and section modulus
 Compute the shear stress
For rectangular steel beam, maximum shear stress is
 max

1 .
5
V
A

A vertical structural member subjected to axial compression loading.
Used where overhead loads are to be carried
Classified as long, intermediate or short depending on the span to depth ratio.
Short columns fail by yielding
Long columns fail by buckling
Slenderness Ratio: (Important parameter in design) is the ratio of the effective length to the least lateral dimension.
Wooden columns could be
 Single load timber
 Solid timber with lamination of planks
 Open column composed of planks but separated by spaces
Design Concepts
The FAO and Leonhard Euler method

of
Engineering properties of construction materials are broadly grouped into the following:
 Physical – bulk density, specific gravity, porosity, void ratio, permeability, colour, size, shape and smell
 Mechanical tensile and compressive strength, modulus of elasticity, rupture, shear strength, hardness, impact, endurance and creep behavior
 Thermal thermal conductivity, expansion, contraction and specific heat
 Chemical -
 Acoustical -

 Strength
 Durability
 Resistance to corrosion
 Hardness
 Toughness
 Resilience
 Workability
 Dimensional stability

Selection depends on:
 Type and functions of the building and specific characteristics
 Adequacy of relevant properties
 Ease of handling
 Appropriateness
 Ease of site adjustment
 Economic aspects of the building in terms of original investment
 Availability of the materials in the area
 Availability of skilled labour
 Quality and durability of different materials
 Cultural acceptability

 Earth: Advantages and disadvantages
 Natural fibres- bamboo, leaves, sisal
 Wood and wood products
 Concrete –cement, aggregates,water

 Facilities: De-skilling the operation
Simulation and optimization
Computer aided drafting
Advantages
 Very fast
 Accurate
 Greater scope and limited
 Can be modified

 Computer aided design (CAD)
 Computer aided manufacturing (CAM)

1.
Farm structures in tropical climates by L.P. Bengtnos and J.H. Whitaker
(FAO)
2.
Agricultural buildings and structures by J.H. Whitaker
3.
Mid west plan service- structures and environmental handbook