D45 CHECK YOUR LEVEL

Assertion (A): Still basin is provided after spillway. Reason (R): It prevents scouring downstream.

• Both A and R are true and R is correct explanation
• Both A and R are true but R is not the correct explanation
• A is true but R is false
• A is false but R is true

Answer explanation

Stilling basin reduces energy and prevents erosion—hence, R explains A.

Statement 1: Quick lime is obtained by burning pure limestone. Statement 2: Slaked lime is calcium carbonate.

• Only Statement 1 is correct
• Only Statement 2 is correct
• Both are correct
• Both are incorrect

Answer explanation

Quick lime is CaO; slaked lime is Ca(OH)₂, not CaCO₃. Only S1 is correct.

Statement 1: Eutectoid steel contains 0.8% carbon. Statement 2: Cast iron has lower carbon than steel.

• Only S1 is true
• Only S2 is true
• Both are true
• Both are false

Answer explanation

S1 is true; cast iron has higher carbon (2–6%) than steel.

Which of the following contributes to the reduction of creep in concrete?

• Increase in W/C ratio
• Use of plasticizers
• Higher cement content
• Use of larger aggregate

Answer explanation

Larger aggregates reduce creep by restraining deformation.

The influence line for shear just right of a support in simply supported beam drops suddenly because:

• Point load acts instantly
• Support takes reaction
• Moment becomes zero
• No strain develops

Answer explanation

Reaction jump causes shear value to change abruptly.

A parabolic arch carries a uniformly distributed load. The bending moment at any point in the arch is:

• Zero
• Maximum at crown
• Maximum at springing
• Uniform

Answer explanation

Parabolic arch under UDL has no BM, only axial thrust.

The reinforcement for torsion in beams is provided by:

• Vertical stirrups
• U-bars
• Closed stirrups with longitudinal bars
• Only main bars

Answer explanation

Torsional reinforcement = closed stirrups + longitudinal bars.

The reduced level of a station is calculated as:

• RL of BM – back sight
• RL of BM + back sight
• RL of previous station – foresight
• RL of previous station + foresight

Answer explanation

RL = BM + BS (in HI method).

In AutoCAD, the 'DIMLINEAR' command is used to:

• Draw arc dimensions
• Place aligned dimensions
• Create linear dimensions
• Draw ordinate dimensions

Answer explanation

DIMLINEAR adds linear horizontal/vertical dimensions.

Which IS code is used for general construction steel design?

• IS 456
• IS 800
• IS 875
• IS 1893

Answer explanation

IS 800 governs general steel design.