ERT 348/3 Controlled Environment Design 1

1. ERT 348/3Controlled Environment Design 1 Siti Kamariah Binti Md Sa’at sitikamariah@unimap.edu.my 012-7549710

2. Course • This course covers engineering designand analysis of agricultural related structures and environmental systems and requirements for crops and animals, specifically structural design and analysis of timber, concrete, and steel elements of agricultural buildings, greenhouses, and structures for livestocks husbandry.

3. Text @ Reference book • Hibbeler, R.C. (2006). Structural Analysis, 6th Ed. Prentice Hall. • McKenzie, W.M.C (2004) Design of structural elements. Palgrave McMillan, UK • Al Nageim, H., Durka, F., Morgan and Williams,D (2003) Structural Mechanics Loads, Analysis, Design and Materials, 6th Edition, Prentice Hall

4. Course Outcomes: • CO1:Ability to design structural members in tension, compression, and bending. • CO2: Ability to plan and design farm infrastructures, agricultural buildings, crops and animal protection structures. • CO3:Ability to plan and design a farmstead and estimate cost of construction and maintenance.

5. Behavior of structure • Structural Mechanics • Structural Design

6. Structural Mechanics • The science that describes and predicts the conditions under which structures remain or should remain at rest under the action of various loads or forces. • That means the structure must not collapse.

7. Structural design • The process of choosing a suitable system or framing arrangement to support shape or a form and prevent it from collapsing. • The support system is called structure. • Structures refer to a system of connected parts used to support a load • A structure is made from one part only or from individual parts called structural elements. • Structural elements are the parts of the frame that help to support the structure.

8. Structural Element • Tie rods • Beams • Columns

9. Types of structure • The combination of structural elements and the materials from which they are composed is referred to as a structural sysyem. • Each system is constructed of one or more of four basic types of structures. • Types of structures

10. Types of structure

11. Structural design • Factors to consider:

12. Structural Classification • Structures are classified according to their use and need:

13. The purpose of a structure • To transmite loads from the point of application to the point of support and ultimately through the foundation to the ground. • That purpose must be fulfilled within the constrain imposed by client’s requirement (low initial costs and low maintenance costs and may vaguely stipulate the fuctional needs of project)

14. Project design team • The design project team normally consists of the following: • Architectural engineers- preparing structural plans/model/computer simulation; employ consultant engineers

15. Project design team 2. Consultant- carry out the detailed design; prepare tender documents (material); make decision about materials, structural types and form, and design method; supervise, inspect and approve materials, fabrication and construction activities; inspect construction activities. They include structural, electrical, mechanical, as well as quantity surveyors and building surveyors. Contractors may also be consulted at this stage

16. Project design team 3. Builders or contractors- carry out all the construction activities such as earthworks, foundations, fabrication of structural elements and building frameworks, walls, bracing, finishes, installation of equipment and services.

17. The design process- 2 stages • The conceptual design and planning stages • based on experience, intuition and knowledge to make imaginative choice of preliminary scheme in layout,material and erection method and which materials could be used. • They will examine the structural site and ensure site suitable for construction. • The behavior of supporting ground under load applied by the structure should be fully investigate (soil investigation- soil structure and profile) to select the types of foundation.

18. The design process- 2 stages 2. The detailed design stage • Idealization of the structure and any complex part of the structure by mathematical models for the analysis and design processes. • Estimation of all relevant loads and any realistic combination of loads • Design all the structural elements such as foundations, walls, structural frames and connection. • Preparation of final detailed drawings, material lists, specifications of fabrication and construction activities, bill of quantity and tender documents.

19. Design method and design philosophies • Elastic or permissible stress method • Load factor method or plastic theory • Limit state design method • Design codes • Structural Loading

20. Elastic or permissible stress method • The design stresses of materials are calculated by dividing their ultimate strength by a factor of safety. • Permissible stress = • The size of structural elements is selected on the basis that the actual stress of the material will experience under applied loads, during its design life must be kept within the elastic region.

21. Stress-strain curves for steel

22. Elastic or permissible stress method • Because of elastic theory is based on the elastic stress distribution, the method is nota pplicable to a semi-plastic material such as concrete. It also not suitable when the deformation of structural element in not proportional to the load.

23. Example 1.1 • Calculate the cross-sectional area and the diameter of a circular mild steel bar that is required to safely required to support a dead load of 5 kN and imposed load of 2 kN. The yield stress (ultimate strength) of mild steel is 250 N/mm2. Use a factor of safety of 1.8 for the material strength.

24. Solution

25. Load factor method or plastic theory • Load factor = • The working loads are multiplied by a factor of safety, with the ultimate strength of the materials being used, and the design load is defined as: design load= working loads x factor of safety • The load factor method or plastic theory is based on funding the load that cause the structure to fail. • Then, the working load is the collapse load that cause plastic to deformed.

26. Stress-strain curves for plastic method Stress Plastic range or plastic deformation Strain hardening Failure Yield stress Strain

27. Limit state design method • Two types of limit state in order to ensure an adequate degree of safety and serviceability. • _________________ - In which condition, e.g deflection, vibration or cracking occurs to an extent, which is unacceptable. • _________________ - In which the structure, or some part of it, is unsafe for its intented purpose, e.g. Compressive, tensile,shear or flextural failure or instability leading to partial or total collapse.

28. Limit state design method • In limit state design menthod, partial safety factor are used, separating the probability of failure due to overloading due to variability of strength of the materials.

29. Characteristic strength & design strength of material • The use of characteristic values enables the ___________________of various parameters such as material strength, different load types, etc. to be incorporated in an assessment of the acceptable probability that the valur of parameter will be exceeded during the life of a structure. • Normally refers to a value of such magnitude that statically only _____ probability exists of its being exceeded.

30. Characteristic strength & design strength of material • Characteristic strength of material, fk is defined as the value of material strength below which result unlikely to fall. • Design strength of material = fk/γm, where γm is the partial factor of safety. • The partial factor of safety takes into account possible variation such as construction tolerance and quality control both in manufacturing and construction. For example steel quality control required both in selection raw material snd during rolling and construction process.

31. Characteristic strength for materials

32. Design codes • The design codes are specific to individual materials: • BS 8110 – • BS 5950 – • BS 5268 – • BS 5628 –

33. Design codes • For the codes, there are based on material characteristics such as stress-strain relationship, the modulus of elasticity, Poissson’s ratio and inherent variability both within manufacture and processes during construction. • Currently for timber design codes is ‘permissible stress’ design codes and for concrete, steelwork and masonry are based on ‘limit state’ design philisophy.

34. Structural Loading • In design, the loads of buildings and structures are classified into different types based on their frequency of occurence an method of assessment. These are: • ____________ • ____________ • ____________ • Earth and liquid pressures • Other load such as thermal effects, ground movement, shinkage and vibration.

35. Dead Loads • BS 6399-1:1996 Loading for buildings, Part 1: Code of Practice for dead and imposed load • Dead load is the weight of structural components such as self-weight of beams, column, floors, walls, roof and finishes and includes other permanent attachments to structures likes pipe,electrical conduits, heating ducting and all items intended to remain in place throughout the life of structure. • It is calculated from BS 648:1964

36. Imposed loads (Live loads) • BS 6399-1:1996 Loading for buildings, Part 1: Code of Practice for dead and imposed load • Imposed load are sometimes called live load. They are gravity loads varying in magnitude and location. The value adopted are based on intented occupancy or use of structure (furniture and storage of material). They includes distributed, concentrated, impact and snow load but exclude wind load. • Loading are considered in the following categories:

37. Imposed loads • Domestic and residential activities • Offices • Institutional & exhibition • Industrial • Bridges • Shopping Areas • Warehouse and storage areas

38. Wind Loads • BS 6399-2:1997 Loading for buildings, Part 2: Code of Practice for wind load • Wind load depend on wind in the environment and on the arerodynamic and aerolastic behavior of the building. • Wind load on structures are dynamic loads due to changes in wind speed. • For convenience in design, it is usual practice to consider the wind load as static loads.

39. Characteristic load • There are symbol used: • Gk = _____________________ • Qk = _____________________ • Wk= ______________________ • Uppercase letter eg. Gk use for concentrated loads and lower case letters eg. Gk for distributed load.

40. Design load • The design load is calculated by multiplying the characteristic load by the appropriate partial safety.

41. Load combination • The following values for the partial safety factors applied to loads are given in most limit state design codes. • Dead load,Gk and imposed load,Qk Design dead load = or 1.4 Gk or 1.0 Gk Design imposed load = 1.6 Qk Design load = 1.4 Gk + 1.6 Qk (vertical load) • Dead load,Gk and wind load,Wk Design dead load = 1.4 Gk or 1.0 Gk Design wind load = 1.4 Wk • Dead load,Gk imposed load,Qk and wind load,Wk Design dead load = 1.2 Gk Design imposed load = 1.2 Qk Design wind load = 1.2 Wk or 0.015Gk where 1.2 Gk + 1.2 Qk (vertical load) + 1.2 Wk

42. Continous beam design • In the design of continous beam, the worst load combination should be associated with the design dead load of 1.0Gk acting on some part of the structure to give the most severe condition. • Case III shows more load combinations are possible in this case. • Case I, dead load = 1.0Gk and for case II, dead load = 1.0Gk and 1.4Gk for load resisting uplift or overtuning.

43. Load combination • Case I

44. Load combination • Case II

45. Load combination • Case III

46. Example 2.1 • Figure 2.3 shows a 3m long reinforced concrete beam and a 914mm deep x 419mm wide universal steel beam 6m long. Calculate the following: • The weight of each beam per unit length (the uniformly distributed loads per unit length) • The total weight of each beam • The design dead load for each beam 0.4m 0.2m 3m