Civil Engineering PE Reinforced Concrete Design 3

Question 1

A short square tied column (16×16 in) has 8-#9 bars. With f'c = 5000 psi and fy = 60,000 psi, what is the nominal axial load capacity Po?

Accepted Answer

1,310 kips

Answer

Po = 0.85f'c(Ag - Ast) + fyAst = 0.85(5)(256 − 8.0) + 60(8.0) = 1,054 + 480 = 1,534 kips nominal; select the closest provided option.

Question 2

The balanced reinforcement ratio ρb for a singly reinforced beam with f'c = 4000 psi and fy = 60,000 psi is approximately:

Accepted Answer

0.0214

Answer

ρb = (0.85β1 f'c/fy) × (87,000/(87,000+fy)) = (0.85×0.85×4/60) × (87/147) ≈ 0.0285 × 0.592 ≈ 0.0214.

Question 3

For a one-way slab with a 15-ft simple span, the minimum ACI 318 thickness to avoid deflection calculations is:

Accepted Answer

8 in

Answer

ACI minimum thickness = L/20 = 15 ft × 12 in/ft / 20 = 9 in; answer reflects L/20 rule.

Question 4

The strength reduction factor φ for shear and torsion in reinforced concrete per ACI 318-19 is:

Accepted Answer

0.75

Answer

ACI 318-19 Table 21.2.1 assigns φ = 0.75 for shear, torsion, and bearing in reinforced concrete members.

Question 5

Torsional effects in a reinforced concrete beam can be neglected per ACI 318 when the factored torsional moment Tu is less than:

Accepted Answer

φ(√f'c/12)(Acp²/Pcp)

Answer

ACI 318 Section 9.5.4.1 allows torsion to be neglected when Tu < φ(√f'c/12)(Acp²/Pcp) for solid sections.

Civil Engineering PE Practice Test