This educational application supplements, but does not replace, the official AASHTO LRFD Bridge Design Specifications, applicable state DOT manuals, project specifications, and professional engineering judgment.
Graded quiz
Chapter 3 — Loads and Load Combinations (20 questions)
20 questions · PE-exam format · 70% to pass · attempts save to your progress record when signed in.
Work each item to the requested precision. Use the Show clue button only after an honest attempt — hints reveal the AASHTO section and setup, not the answer.
- Q1
HL-93 design truck: front axle 8 kip, two 32-kip rear axles at 14 ft. Compute the truck total weight (kip).
kipHL-93 design truck
- Q2
Placing the truck symmetrically on an L = 40 ft simple span (14-ft rear-axle spacing, front axle off span), compute maximum midspan moment from the truck alone using absolute maximum by Barré's theorem — placing both 32-kip axles equidistant from centerline. Report M (k-ft).
k-ftHL-93 design truck
- Q3
Lane load: w = 0.64 klf, L = 40 ft simple span. Compute midspan M (k-ft).
k-ftHL-93 design lane load
- Q4
Total HL-93 midspan LL moment (truck+lane, IM = 33% on truck), L = 40 ft. Truck = 449 k-ft, lane = 128 k-ft. Compute total MLL+IM (k-ft).
k-ft - Q5
Design tandem consists of:
- Q6
For a short span L = 20 ft, tandem (2×25 kip @ 4 ft) placed for max midspan moment gives Mtandem = 220 k-ft. Add lane. Compute total LL+IM using IM = 33%.
k-ftLane on short span
- Q7
Multiple presence factor m for 3 loaded lanes is:
- Q8
An interior girder distribution factor for two or more design lanes (moment, cross-section a): DF = 0.075 + (S/9.5)⁰·⁶ × (S/L)⁰·² × (Kg/(12L·ts³))⁰·¹. For S = 8 ft, L = 60 ft, Kg/(12Lts³) = 1.0, compute DF.
- - Q9
Wind on structure (WS) at Service I is typically:
- Q10
Wind pressure PD = 0.050 ksf, exposed superstructure depth d = 10 ft. Compute uniform lateral load w (klf) on the girder line.
klfWind on structure
- Q11
Braking force BR per §3.6.4 is the larger of:
- Q12
Two 12-ft lanes loaded. Truck = 72 kip. Compute BR per lane using 25% of axle weights, with multiple-presence m = 1.0 (2 lanes).
kip - Q13
Temperature range Procedure A for steel superstructure (moderate climate) is:
- Q14
Steel bridge L = 200 ft, ΔT = 150°F, α = 6.5×10⁻⁶ /°F. Compute free thermal elongation ΔL (in).
in - Q15
Vehicular collision force (CT) per §3.6.5 on a pier not protected by a 42-in redirecting barrier is:
- Q16
Deck overhang: 10 kip wheel load 3 ft from face of barrier. Compute moment at fascia girder support (k-ft) per foot width, ignoring lane load. Assume tributary width = 4 ft.
k-ft/ftDeck overhang
- Q17
Placing a UDL to maximize a positive-quantity ordinate on an influence line requires loading:
Influence line — reaction at A
- Q18
Fatigue truck ADTTSL ≥ 20 uses which fatigue limit state?
- Q19
DL only (no LL): wDC = 4.0 klf, L = 120 ft. Compute Strength IV midspan Mu using γDC = 1.50 (k-ft).
k-ftStrength IV example
- Q20
Skew correction for shear in exterior girder, θ = 30°: multiplier ≈ 1.0 + 0.20(tan θ). Compute multiplier.
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