Civil Engineering PE Prep 3 — Questions and Answers
Question 1: A 10-ft diameter circular pipe flows half-full. The hydraulic radius is:
- 2.5 ft (Correct answer)
- 5.0 ft
- 1.25 ft
- 3.54 ft
Correct answer: 2.5 ft
For a circular pipe at half-full, R = D/4 = 10/4 = 2.5 ft.
Question 2: Which AASHTO soil classification group generally represents the best subgrade material?
- A-1-a (Correct answer)
- A-7-6
- A-4
- A-6
Correct answer: A-1-a
A-1-a represents well-graded gravel and sand with excellent subgrade performance (GI = 0).
Question 3: The critical path in a CPM schedule is defined as the sequence of activities that:
- Has zero total float and determines project duration (Correct answer)
- Has the most activities
- Has the highest cost
- Contains all milestones
Correct answer: Has zero total float and determines project duration
The critical path consists of activities with zero total float; any delay extends the project end date.
Question 4: A steel column with an effective length KL = 15 ft and radius of gyration r = 2 in has a slenderness ratio of:
- 90 (Correct answer)
- 180
- 7.5
- 45
Correct answer: 90
KL/r = (15×12)/2 = 180/2 = 90.
Question 5: In stormwater design, the Rational Method formula Q = CiA requires the rainfall intensity (i) to be evaluated at:
- The time of concentration of the watershed (Correct answer)
- The 100-year storm duration
- 24-hour rainfall total
- The 2-year storm frequency
Correct answer: The time of concentration of the watershed
i is selected from IDF curves at the storm frequency and duration equal to the time of concentration.
Question 6: For a prestressed concrete beam, the term 'prestress losses' refers to:
- Reduction in initial prestress force over time due to creep, shrinkage, and relaxation (Correct answer)
- Cracking of concrete at transfer
- Loss of aggregate bond
- Reduction in beam depth due to loading
Correct answer: Reduction in initial prestress force over time due to creep, shrinkage, and relaxation
Prestress losses include elastic shortening, creep, shrinkage of concrete, and relaxation of tendons.
Question 7: A horizontal curve on a highway has a radius of 1,500 ft and a design speed of 60 mph. The required superelevation is most closely governed by:
- AASHTO Green Book design tables balancing e and f (Correct answer)
- Only the maximum friction factor
- Only the posted speed limit
- State drainage standards alone
Correct answer: AASHTO Green Book design tables balancing e and f
AASHTO distributes superelevation (e) and side friction (f) per design speed and radius tables.
Civil Engineering PE Prep 3
A 10-ft diameter circular pipe flows half-full.
The hydraulic radius is: