Civil Engineering PE Reinforced Concrete Design 2

Question 1

A rectangular beam has b = 14 in, d = 22 in, f'c = 4000 psi, fy = 60,000 psi, and As = 3.0 in². What is the approximate nominal moment capacity Mn?

Accepted Answer

248 ft-kips

Answer

210 ft-kips

Answer

185 ft-kips

Answer

270 ft-kips

Question 2

According to ACI 318, the minimum clear cover for reinforcement in a concrete beam exposed to weather (deicing salts) is:

Accepted Answer

2.5 in

Answer

1.5 in

Answer

2.0 in

Answer

3.0 in

Question 3

For a doubly reinforced concrete beam, the compression steel stress f's is typically determined by:

Accepted Answer

Using strain compatibility with εs' = (c - d')/c × 0.003

Answer

Assuming f's = fy always

Answer

Setting f's = 0.85f'c

Answer

Using f's = 0.5fy as an ACI simplification

Question 4

A T-beam floor system has a 5-in slab, beam web width bw = 12 in, center-to-center spacing of beams = 72 in, and span = 20 ft. The effective flange width per ACI 318 is:

Accepted Answer

60 in

Answer

48 in

Answer

66 in

Answer

72 in

Question 5

The ACI 318 minimum shear reinforcement for a beam is not required when:

Accepted Answer

Vu ≤ φVc/2

Answer

Vu > φVc/2

Answer

Vu > φVc

Answer

The beam depth exceeds 24 in

Question 6

The development length for a #8 top bar (f'c = 4000 psi, fy = 60,000 psi, normal weight concrete, cover = 1.5 in, no transverse reinforcement) is approximately:

Accepted Answer

60 in

Answer

36 in

Answer

48 in

Answer

72 in

Question 7

Which failure mode must be prevented to ensure ductile behavior in a flexural member per ACI 318?

Accepted Answer

Concrete crushing before tension steel yields

Answer

Tension steel yielding before concrete crushes

Answer

Diagonal tension failure

Answer

Bond failure at midspan