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 4 — Bridge Analysis and Structural Modeling (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
The stiffness (K) method for grid analysis of a bridge deck assembles:
- Q2
Simple beam, EI constant. w = 3.0 klf, L = 60 ft, E = 29,000 ksi, I = 22,000 in⁴. Compute midspan deflection δ = 5wL⁴/(384 EI) in inches.
inSimple span — uniform load
- Q3
For a two-span continuous beam with equal spans and uniform w, the moment at the interior support is:
Two-span continuous
- Q4
Two-span continuous, L = 80 ft each, w = 4 klf. Compute interior support M (k-ft, magnitude).
k-ft - Q5
The AASHTO §4.6.2.2 approximate distribution-factor method requires:
- Q6
Longitudinal stiffness parameter K_g = n(I + A e_g²). For n = 8, I = 12,000 in⁴, A = 30 in², e_g = 30 in, compute K_g (in⁴).
in⁴ - Q7
Müller-Breslau's principle states the influence line for a reaction/force is proportional to the:
Influence line — reaction at A
- Q8
Simple beam, P = 20 kip at a = 15 ft from left, L = 40 ft. Compute reaction R_A (kip).
kipSimple span — point load
- Q9
Same case: compute maximum moment under the load (k-ft).
k-ftSimple span — point load
- Q10
A grillage analysis for a slab-on-girder bridge models the deck slab as:
- Q11
Refined analysis under §4.6.3 is preferred when:
- Q12
Cantilever, P = 25 kip at tip, L = 10 ft. Compute fixed-end moment (k-ft).
k-ftCantilever
- Q13
Same cantilever: compute tip deflection δ = PL³/(3EI). E = 29,000 ksi, I = 800 in⁴. Report in inches.
inCantilever
- Q14
The service-limit-state deflection limit for a vehicular bridge (optional) is:
- Q15
Live-load deflection L = 90 ft, computed δ = 1.05 in. Check against L/800 limit — report the limit in inches.
in - Q16
Torsional stiffness J for a hollow closed box section (single cell) is best given by:
- Q17
Box: A_o = 200 in², perimeter/t sum = 200. Compute J (in⁴) using Bredt-Batho: J = 4A_o²/∮(ds/t).
in⁴ - Q18
Effective flange width per §4.6.2.6 for interior girders equals:
- Q19
Cross-section a (concrete beam + slab): interior girder S = 8 ft, span L = 60 ft, K_g/(12Lt_s³) = 1.0. Compute one-lane DF for moment: DF = 0.06 + (S/14)^0.4 (S/L)^0.3 × [K_g/(12Lt_s³)]^0.1.
- - Q20
For a straight steel bridge, the AASHTO approximate live-load distribution factor method applies to how many girders minimum?
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