BCE Reinforced Concrete Design

Question 1

In the ACI 318 strength design method, which load combination is used for dead load (D) and live load (L)?

Accepted Answer

U = 1.2D + 1.6L

Answer

ACI 318-19 specifies U = 1.2D + 1.6L as the governing load combination for dead and live loads in the strength design (LRFD) method.

Question 2

The strength reduction factor φ for tension-controlled beams in ACI 318 is:

Accepted Answer

0.90

Answer

ACI 318 assigns φ = 0.90 for tension-controlled sections (net tensile strain ≥ 0.005), reflecting high confidence in flexural strength calculations when ductile failure governs.

Question 3

What does the balanced reinforcement ratio (ρb) represent in beam design?

Accepted Answer

The steel ratio at which concrete and steel simultaneously reach their limiting strains

Answer

The balanced reinforcement ratio ρb is the theoretical steel ratio at which concrete reaches εcu = 0.003 and tensile steel reaches yield strain simultaneously at the same load.

Question 4

For a simply supported rectangular beam, the location of maximum bending moment is at:

Accepted Answer

Midspan (for uniform load)

Answer

For a simply supported beam with a uniformly distributed load, the maximum bending moment occurs at midspan and equals wL²/8.

Question 5

Which mode of shear failure in a reinforced concrete beam is prevented by stirrups?

Accepted Answer

Diagonal tension cracking leading to shear failure

Answer

Stirrups (transverse reinforcement) cross diagonal tension cracks, preventing sudden shear failure by transferring tensile forces across cracks and confining the concrete.

BCE - Bachelor of Civil Engineering Practice Test

BCE - Bachelor of Civil Engineering Practice Test

BCE Reinforced Concrete Design