Projected Area Method in Structural Design
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Questions and Answers

What is a limitation of the projected area method in structural design?

  • It is suitable for all types of structures
  • It requires advanced computational techniques
  • It cannot be used for structures taller than 200 ft (correct)
  • It solely relies on wind direction

    • Which of these loads on suspended floors is the highest for horses?

  • 4.9 kN/m² (correct)
  • 1.5 kN/m²
  • 2.5 kN/m²
  • 3.4 kN/m²

    • What is the mass of maize, shelled, per cubic meter?

  • 770 kg/m³
  • 720 kg/m³ (correct)
  • 450 kg/m³
  • 577 kg/m³

    • Which method is described as simple and satisfactory for most structures?

    <p>Projected area method</p> Signup and view all the answers

    Which load is applied per square meter for pigs on a slatted floor weighing 180 kg?

    <p>3.2 kN/m²</p> Signup and view all the answers

    Which of the following is the mass of silage per cubic meter?

    <p>480-640 kg/m³</p> Signup and view all the answers

    Which classification pertains to nails in relation to service?

    <p>Nailed connections</p> Signup and view all the answers

    What is the load applied per square meter for loose housing for cattle?

    <p>3.9 kN/m²</p> Signup and view all the answers

    What is the recommended window area for sitting rooms and workrooms relative to the floor area?

    <p>5 to 10%</p> Signup and view all the answers

    Which method is NOT suggested for shading windows in livestock housing?

    <p>Applying window tinting</p> Signup and view all the answers

    What happens to the allowable withdrawal load for nails driven into end grain compared to those driven into side grain?

    <p>It is reduced to half for end grain.</p> Signup and view all the answers

    What is a primary objective of poultry housing?

    <p>Promoting health and maximizing production</p> Signup and view all the answers

    What essential element must be managed to prevent disease in poultry houses?

    <p>Excess moisture in the air</p> Signup and view all the answers

    What is the minimum temperature recommended for farrowing sows?

    <p>50° F</p> Signup and view all the answers

    Which formula is used to calculate the allowable withdrawal load for nails driven into seasoned wood?

    <p>$P = 1380 G2.5D$</p> Signup and view all the answers

    Which site condition is crucial for maintaining the effectiveness of poultry housing?

    <p>Protection from prevailing winds</p> Signup and view all the answers

    Which animal type has the highest daily water requirement?

    <p>Boars</p> Signup and view all the answers

    What does the variable 'D' represent in the withdrawal load formula?

    <p>Nail diameter in inches.</p> Signup and view all the answers

    For pigs in a cold climate, what is the recommended apparatus to use?

    <p>Heated hovers</p> Signup and view all the answers

    Which of the following statements about the connection created by nails driven parallel to the grain is true?

    <p>It is inherently weak and not permitted.</p> Signup and view all the answers

    Why is drainage an important consideration when selecting a site for poultry housing?

    <p>To prevent undesirable dampness</p> Signup and view all the answers

    What does the variable 'M' represent in the bending stress formula?

    <p>Maximum bending moment of the beam.</p> Signup and view all the answers

    What space requirement is suitable for fattening hogs that weigh on average 750 lb?

    <p>6 to 10 sq.ft</p> Signup and view all the answers

    What is the main benefit of having plenty of sunlight in a poultry house?

    <p>It enhances the birds' cheerfulness</p> Signup and view all the answers

    What is the standard floor area required for a breeding cow with or without a calf?

    <p>50 sq.ft</p> Signup and view all the answers

    What factor must be considered to achieve sanitary conditions in livestock housing?

    <p>Effective waste management</p> Signup and view all the answers

    What is the main purpose of the compression force C in the moment resistance of a concrete section?

    <p>To resist bending moments</p> Signup and view all the answers

    Which of the following breeds has the lowest weight requirement in terms of square footage?

    <p>Calf</p> Signup and view all the answers

    What is the maximum horizontal shearing stress expressed as in the design formula?

    <p>$ rac{3}{2}(V/A) &lt; \sigma ’V$</p> Signup and view all the answers

    Which parameter is used to determine the allowable bending stress in a beam?

    <p>Maximum bending moment.</p> Signup and view all the answers

    What is a negative condition for hogs in housing?

    <p>Dampness</p> Signup and view all the answers

    For the water consumption of pigs, what is the maximum gallons they can consume per day?

    <p>1.5 gallons</p> Signup and view all the answers

    What is the formula for the adjusted allowable compressive stress for long columns?

    <p>$\s’C \ = 0.30 E / (SR)^{2}$</p> Signup and view all the answers

    In the design of axial tension members, which variable represents the allowable tensile stress?

    <p>$ ’$</p> Signup and view all the answers

    What does the variable J represent in the combined bending and axial compression equation?

    <p>Modifier for the P-Δ effect</p> Signup and view all the answers

    For a balanced design of a reinforced concrete beam, what is ideally triggered at the same time?

    <p>Concrete and steel bars reach limiting stresses simultaneously</p> Signup and view all the answers

    Which formula represents the interaction of actual tensile stress and allowable tensile stress?

    <p>$(\sigma_t / \sigma_t') + (\sigma_b / \sigma_b') &lt; 1.0$</p> Signup and view all the answers

    In the context of reinforced concrete, what does the term 'd' refer to?

    <p>Effective depth of the section for stress analysis</p> Signup and view all the answers

    For short columns, what is the value of the modifier J in the combined bending and axial compression formula?

    <p>0</p> Signup and view all the answers

    In the horizontal shear stress design formula, what does 'A' stand for?

    <p>Cross-sectional area of the beam.</p> Signup and view all the answers

    What does the symbol $ ext{As}$ represent in the context of reinforced concrete design?

    <p>Cross-sectional area of the reinforcing steel bars</p> Signup and view all the answers

    In a combined bending and axial tension condition, what must the sum of the ratios equal?

    <p>&lt; 1.0</p> Signup and view all the answers

    What is the relationship between the moment resistance and the area of steel in a reinforced concrete section?

    <p>Moment resistance increases with area of steel</p> Signup and view all the answers

    Which of the following represents the formula for calculating the moment resistance using the compression force?

    <p>$M = Cjd$</p> Signup and view all the answers

    What does the ratio p represent in the design of a reinforced concrete beam?

    <p>Percentage of reinforcing</p> Signup and view all the answers

    What is the significance of the variable $ ext{fc}$ in reinforced concrete design?

    <p>Maximum compressive stress in concrete</p> Signup and view all the answers

    Study Notes

    Projected Area Method

    • Simple design method suitable for most structures.
    • Not applicable to gable rigid frames or structures exceeding 200 ft in height.

    Loads on Suspended Floors

    • Cattle:
      • Tie stalls: 3.4 kN/m²
      • Loose housing: 3.9 kN/m²
      • Young stock (180 kg): 2.5 kN/m²
    • Sheep: 1.5 kN/m²
    • Horses: 4.9 kN/m²
    • Pigs:
      • Slatted floor (90 kg): 2.5 kN/m²
      • Slatted floor (180 kg): 3.2 kN/m²
    • Poultry:
      • Deep litter: 1.9 kN/m²
      • Cages: Variable
    • Repair shop allowance: 3.5 kN/m²
    • Machinery storage allowance: 8 kN/m²

    Mass of Farm Products

    • Maize (shelled): 720 kg/m³
    • Maize (ear): 450 kg/m³
    • Wheat: 770 kg/m³
    • Rice (paddy): 577 kg/m³
    • Soybeans: 770 kg/m³
    • Dry beans: 770 kg/m³
    • Potatoes: 770 kg/m³
    • Silage: 480-640 kg/m³
    • Groundnuts (unshelled): 218 kg/m³
    • Hay:
      • Loose: 65-80 kg/m³
      • Balled: 190-240 kg/m³

    Nailed Connections

    • Withdrawal from end grain is weak and not allowed in design.
    • Allowable withdrawal load is calculated using:
      • P = 1380 G².5D
      • P: Allowable load (lb/in penetration)
      • G: Specific gravity of wood
      • D: Nail diameter (inches).
    • Allowable load for common wire nails in end grain is half of that for side grain.

    Design of Rectangular Wood Beams

    • Bending Stress Formula:
      • σb = M/S < σ'b
      • σb: Actual bending stress, M: Maximum bending moment, S: Section modulus.
    • Horizontal Shear Stress Formula:
      • σV = (3/2)(V/A) < σ'V
      • σV: Maximum shearing stress, V: Design shear, A: Cross-sectional area.

    Columns

    • Long column classification: k < SR < 50.
    • Adjusted allowable compressive stress based on column type:
      • Short: σ'C|| = σ''C||
      • Intermediate: σ'C|| = σ''C|| [1 - (1/3)(SR/k)⁴]
      • Long: σ'C|| = 0.30E/(SR)² where E is modulus of elasticity.

    Design of Axial Tension and Combined Stress Members

    • Tension Member Formula:
      • σt = P/An < σ't
      • An: Net cross-sectional area accounting for bolt holes.
    • Combined Axial and Bending Stress Formula:
      • (σt/σ't) + (σb/σ'b) < 1.0 for tension.
      • [σC||/σ'C||] + [(σb/σ'b) - JσC||] < 1.0 for compression.

    Design of Reinforced Concrete Beams

    • Working Stress Design involves determining moment resistance and stress distribution.
    • Key notations:
      • b: Width of concrete compression zone,
      • d: Effective depth,
      • As: Area of reinforcing bars,
      • p: Percentage of reinforcing,
      • n: Elastic ratio.

    Poultry Housing Considerations

    • Purpose: Ensure comfort, health, production efficiency, and moisture removal.
    • Site must protect against strong winds, provide good drainage, and allow for adequate sunlight.
    • Recommended window area: 5-10% of floor area.

    Livestock Housing

    • General planning considerations include site location, space requirements, environment for productivity, and sanitation.

    Swine Housing Spacing and Water Requirements

    • Sow: 5-8 gallons/day; 48-80 sq.ft.
    • Pigs: 0.5-1.5 gallons/day; 3-6 sq.ft.
    • Fattening hogs: 1.5-3 gallons/day; 6-10 sq.ft.

    Beef Cattle Housing

    • Breeding cows with calves: 50 sq.ft.
    • Calves: 30 sq.ft.
    • Yearlings: 40 sq.ft.
    • Fattening stock (average 750 lbs): Specific area needed per animal.

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    Description

    This quiz tests knowledge on the Projected Area Method, a straightforward approach for designing various structures. While effective for most, it has limitations, particularly with gable rigid frames and tall structures exceeding 200 feet. Test your understanding of its application and constraints.

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