SUNDAY LIVE EXAM (29-06-2025)

A bar of length 2 m is fixed between two unyielding supports and heated by 40°C. The coefficient of thermal expansion is 12 x 10⁻⁶ /°C and E = 200 GPa. What is the thermal stress developed?

• 96 MPa
• 120 MPa
• 150 MPa
• 80 MPa

Answer explanation

Thermal stress = E * α * ΔT = 200 x 10³ * 12 x 10⁻⁶ * 40 = 96 MPa

A composite bar consists of steel and aluminium parts rigidly connected. The cross-sectional area and modulus of elasticity of steel are twice that of aluminium. If the assembly is subjected to axial load, what is the stress ratio between steel and aluminium?

• 1:1
• 1:2
• 2:1
• 2:3

Answer explanation

In a composite bar with rigid connection, strain in both materials is the same.

Strain compatibility:

σ_steel / E_steel = σ_aluminium / E_aluminium

Stress ratio:

σ_steel / σ_aluminium = E_steel / E_aluminium

Given:

E_steel = 2 × E_aluminium

Therefore:

σ_steel / σ_aluminium = 2 × E_aluminium / E_aluminium = 2

Final Answer:

σ_steel / σ_aluminium = 2:1

In a three-hinged parabolic arch, if the live load moves towards the right support, what happens to the horizontal thrust?

• It increases
• It decreases
• It remains constant
• It oscillates

Answer explanation

In a parabolic arch, as load moves towards support, horizontal thrust increases.

The degree of kinematic indeterminacy of a rigid jointed plane frame with 5 joints, 7 members, and 3 external reactions is:

• 6
• 12

• 8
• 5

Answer explanation

Kinematic indeterminacy = 3j - R = 3*5 - 3 = 12.

The maximum positive bending moment in a simply supported beam due to a moving point load is located at which point?

• Under the load point
• At mid-span
• At quarter-span
• At the support

Answer explanation

For point load, max bending moment occurs under the load point.

In cable analysis, if the central dip of the cable is reduced while keeping the span constant, what happens to the horizontal thrust?

• Horizontal thrust increases
• Horizontal thrust decreases
• Horizontal thrust remains unchanged
• Horizontal thrust becomes zero

Answer explanation

Reducing central dip increases horizontal thrust due to geometry of cable.

Which method among the following is best suited to analyse redundant structures using strain energy principles?

• Unit Load Method
• Castiglano’s Method
• Slope deflection method

• None

Answer explanation

Castiglano’s method is suitable for redundant structures using strain energy.

For a statically determinate structure, what happens if a zero force member is mistakenly removed?

• The structure remains stable
• The structure becomes kinematically unstable
• No effect if it is truly a zero force member
• The structure becomes statically indeterminate

Answer explanation

If a zero force member is mistakenly removed, the structure may become unstable if it was critical for stability.

Calculate the absolute pressure at a point submerged 5 m below the free surface of water. Atmospheric pressure is 101.325 kPa.

• 200.525 kPa
• 250.525 kPa
• 101.325 kPa
• 150.525 kPa

Answer explanation

Absolute pressure = Atmospheric pressure + Hydrostatic pressure = 101.325 + (9.81 * 5) = 150.525 kPa

A water treatment plant delivers 20,000 m³/day. If the maximum daily demand is 1.8 times the average daily demand, calculate the peak demand.

• 36,000 m³/day
• 30,000 m³/day
• 40,000 m³/day
• 45,000 m³/day

Answer explanation

Peak demand = 1.8 × 20,000 = 36,000 m³/day.