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 1 — Introduction to Bridge Engineering (15 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
AASHTO LRFD Strength I is calibrated to what target reliability index β for a component-level failure?
β ≈ 2.5
β ≈ 3.5
β ≈ 4.5
β ≈ 5.5
Q2
In the LRFD design equation Σ η γ Q ≤ φ R_n, the load modifier η is the product of factors reflecting:
Ductility, redundancy, and operational importance
Duration, ratio, and impact
Deck condition, redundancy, and inspection interval
Deflection, rotation, and inertia
$\sum \eta_i \gamma_i Q_i \le \phi R_n$
Q3
A simple-span girder carries a factored uniform dead load w_u = 4.2 klf over L = 80 ft. Compute the design moment M_u at midspan (k-ft).
k-ft
Simple span (DL only)
Q4
Same beam: compute the factored end reaction (kip).
kip
Reactions at supports
Q5
The AASHTO HL-93 design vehicular live load consists of:
Design truck OR design tandem, plus design lane load — governing combination
Design truck AND design tandem simultaneously
Design truck only
Design lane load only
HL-93 design truck
Q6
Compute the dynamic load allowance (impact) applied to a truck axle for Strength I on the deck slab (§3.6.2.1). Report IM as a decimal (e.g., 0.33 = 33%).
-
HL-93 design truck
Q7
HL-93 lane load only (no truck): compute midspan moment on a simple span of L = 60 ft (k-ft). w = 0.64 klf.
k-ft
HL-93 design lane load
Q8
The influence line for the reaction at support A of a simple span is:
A straight line from 1.0 at A to 0 at B
A parabola with peak at midspan
A rectangle equal to 1.0 over the entire span
A cubic curve equal to 0 at both supports
Influence line — reaction at A
Q9
Which of the following is NOT a limit state defined by AASHTO LRFD §1.3?
Strength
Extreme Event
Service
Allowable Stress
Q10
A 30-kip concentrated live load acts at midspan (a = b = 20 ft) of a simple beam. Compute midspan moment (k-ft).
k-ft
Concentrated live load
Q11
Strength I load combination for gravity-dominated bridges uses which live-load factor γ_LL?
1.00
1.35
1.50
1.75
Q12
Service II bottom-flange stress limit for a composite steel section is f ≤ 0.95·R_h·F_yf. For F_yf = 50 ksi, R_h = 1.0, compute the limit (ksi).
ksi
Composite steel girder — service check
Q13
The Fatigue I load combination applies:
1.75 × fatigue truck (single, 30-ft rear-axle spacing) with IM = 0.15
1.75 × HL-93 truck + lane
1.00 × HL-93 truck only
1.35 × design tandem
Q14
For a two-span continuous girder, the maximum negative moment over the interior support due to HL-93 uses:
Two design trucks in adjacent spans, 90% of (2 trucks + lane) per §3.6.1.3.1
One truck placed at midspan of one span only
Lane load only, no truck
Tandem only in one span
Two-span continuous
Q15
Load factor design of a footing: DC = 400 kip, DW = 60 kip, LL+IM = 220 kip. Compute Strength I factored axial load (kip).
kip
Q16
The primary reason bridge design migrated from Allowable Stress (ASD) to Load-and-Resistance-Factor Design (LRFD) is:
Uniform reliability across materials and load types via probabilistic calibration
Simpler arithmetic
It always yields lighter structures
To match international building codes for houses
Q17
Meyerhof bearing check preview: q_ult = γD_fN_q + 0.5γBN_γ. For γ = 0.120 kcf, D_f = 5 ft, B = 9 ft, N_q = 22.5, N_γ = 30.2, compute q_ult (ksf).
ksf
Spread footing
Q18
Which extreme event combines vehicular collision force (CT) with a reduced live load?
Extreme Event I (EQ)
Extreme Event II (IC, CT, CV)
Strength IV
Service III
Q19
Strength IV governs where the dead-to-live ratio is high. Using γ_DC = 1.50 (Strength IV), compute M_u at midspan for w_DC = 2.6 klf, L = 100 ft (k-ft).
k-ft
Strength IV — high DL/LL ratio
Q20
Bridge lifespan design target in AASHTO LRFD is:
25 years
50 years
75 years
100 years

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Bridge Engineering and Design Using AASHTO LRFD

Graduate interactive textbook for civil engineering students. Aligned to AASHTO LRFD Bridge Design Specifications, 10th Edition (2024).

Regional focus

Maryland & Mid-Atlantic — MDOT SHA, VDOT, PennDOT, FHWA.

Educational notice

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.

Developed for engineering education. Unauthorized reproduction, distribution, or commercial use is prohibited.

v1.0 · Reference edition · Aligned to AASHTO LRFD, 10th Edition (2024)