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

With a = Asfy/(0.85f'cb) = 3.0×60/(0.85×4×14) ≈ 3.78 in, Mn = Asfy(d - a/2) = 3.0×60×(22 - 1.89)/12 ≈ 248 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

ACI 318 Table 20.6.1.3 requires 2.5 in clear cover for #6 through #11 bars exposed to weather (deicing salts).

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

Strain compatibility requires εs' = 0.003(c − d')/c, then f's = Es×εs' ≤ fy to verify whether compression steel yields.

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

Effective flange width = min(span/4, bw + 8hf each side, center-to-center) = min(60 in, 12+80=92 in, 72 in) = 60 in.

Question 5

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

Accepted Answer

Vu ≤ φVc/2

Answer

ACI 318 Section 9.6.3.1 allows omission of minimum shear reinforcement when Vu ≤ φVc/2 for most beams.

Civil Engineering PE Practice Test

Civil Engineering PE Practice Test

Civil Engineering PE Reinforced Concrete Design 2