Civil Engineering PE Basic Civil Engineering PE 3

Question 1

A retaining wall must resist an active earth pressure. Using Rankine's theory with φ = 30° and γ = 120 pcf, the active pressure coefficient K_a is:

Accepted Answer

0.333

Answer

K_a = (1−sin φ)/(1+sin φ) = (1−0.5)/(1+0.5) = 0.5/1.5 = 0.333 for φ = 30°.

Question 2

Which type of flow is characterized by a Reynolds number less than 2,000 in pipe flow?

Accepted Answer

Laminar flow

Answer

Laminar flow occurs when Re < 2,000, where fluid moves in smooth parallel layers with no lateral mixing.

Question 3

In a triangular traffic flow diagram, what is represented by the slope of the line from the origin to any point on the flow-density curve?

Accepted Answer

Space mean speed

Answer

The slope of the line from the origin to any point on the q-k curve equals q/k, which by the fundamental equation equals space mean speed (u_s).

Question 4

The modulus of elasticity (E) for structural steel per AISC is:

Accepted Answer

29,000 ksi

Answer

AISC specifies E = 29,000 ksi (200 GPa) as the modulus of elasticity for all structural steel grades.

Question 5

A concrete mix design has a water-cement ratio (w/c) of 0.45. Increasing the w/c ratio to 0.60 will primarily:

Accepted Answer

Decrease compressive strength

Answer

Higher w/c ratios produce more porous cement paste with lower compressive strength per Abrams' water-cement ratio law.

Civil Engineering PE Practice Test