Reinforced Concrete Design Flashcards
7 cards from real Civil Engineering PE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Reinforced Concrete Design flashcards as text
A two-way flat plate has columns on a 20-ft × 20-ft grid. For punching shear, the critical perimeter bo around an interior column (18×18 in, d = 7 in) is:
Answer: 116 in
Critical section is at d/2 from column face: each side = 18+7 = 25 in, bo = 4×25 = 100 in.
The ACI 318 standard hook development length ldh for a #6 bar (fy = 60 ksi, f'c = 4000 psi, normal weight concrete, no confinement) is approximately:
Answer: 14 in
ldh = (0.02ψe fy/(λ√f'c)) × db = (0.02×1.0×60,000/(1.0×√4000)) × 0.75 ≈ 14.2 in.
For a spirally reinforced column, the minimum spiral reinforcement ratio ρs per ACI 318 is:
Answer: 0.45(Ag/Ac - 1)(f'c/fyt)
ACI 318 Section 25.7.3.3 requires ρs ≥ 0.45(Ag/Ac − 1)(f'c/fyt), ensuring the spiral replaces the lost capacity of the shell.
A simply supported beam (span = 24 ft) carries a uniform service dead load of 1.5 k/ft and live load of 2.0 k/ft. The maximum factored moment Mu using ACI load combinations is:
Answer: 468 ft-kips
wu = 1.2(1.5)+1.6(2.0) = 5.0 k/ft; Mu = 5.0×576/8 = 360 ft-kips — select 360.
The slenderness ratio klu/r below which slenderness effects may be neglected for a braced (non-sway) reinforced concrete column is:
Answer: 34 − 12(M1/M2)
ACI 318 Section 6.2.5 allows slenderness to be neglected for braced columns when klu/r < 34 − 12(M1/M2), where M1/M2 is the end moment ratio.
In a beam-column joint, horizontal joint shear Vjh is resisted primarily by:
Answer: A diagonal concrete compression strut
The primary mechanism for joint shear transfer is a diagonal concrete compression strut forming across the joint panel.
For a reinforced concrete wall with hw/lw > 2.0, the critical section for flexural design is located at:
Answer: The base of the wall
For slender walls (hw/lw > 2.0), the critical section for flexure and axial load is at the base where moments are maximum.