CTQP Structures Inspection 4 — Questions and Answers
Question 1: During a CTQP structures inspection, which condition in a concrete bridge deck most directly indicates alkali-silica reaction (ASR)?
- Longitudinal cracking along rebar lines
- Map or pattern cracking with a gel-like exudate (Correct answer)
- Spalling at expansion joints
- Delamination detected by chain drag
Correct answer: Map or pattern cracking with a gel-like exudate
ASR produces characteristic map (crazing) cracking accompanied by a white or clear gel exudate at crack faces.
Question 2: When inspecting a prestressed concrete beam, a rust stain running perpendicular to the beam axis most likely indicates:
- Shrinkage cracking
- Corrosion of prestressing strand (Correct answer)
- Alkali-silica reaction
- Freeze-thaw scaling
Correct answer: Corrosion of prestressing strand
Rust stains perpendicular to the beam axis align with the location of prestressing strands, suggesting strand corrosion.
Question 3: Under FDOT CTQP guidelines, what is the minimum required frequency for routine in-depth inspections of highway bridges?
- Every year
- Every two years (Correct answer)
- Every four years
- Every six years
Correct answer: Every two years
Federal regulations and FDOT guidelines require routine in-depth bridge inspections at a maximum interval of 24 months (every two years).
Question 4: An inspector notices that a steel girder's bottom flange has a crack initiating from a weld toe and propagating into the flange. This is best classified as:
- Fatigue cracking (Correct answer)
- Lamellar tearing
- Stress corrosion cracking
- Hydrogen embrittlement
Correct answer: Fatigue cracking
Cracks originating at weld toes and growing under cyclic traffic loading are the classic signature of fatigue cracking in steel bridge members.
Question 5: Which instrument is most appropriate for measuring the depth of a surface crack in a concrete bridge component during a field inspection?
- Schmidt rebound hammer
- Ultrasonic pulse velocity (UPV) device (Correct answer)
- Pachometer (cover meter)
- Crack comparator card
Correct answer: Ultrasonic pulse velocity (UPV) device
A UPV device can estimate crack depth by comparing pulse travel time through cracked versus uncracked paths.
Question 6: During scour inspection of a bridge pier after a flood event, the inspector should FIRST:
- Probe the streambed adjacent to the footing with a rod (Correct answer)
- Review hydraulic calculations from the bridge design file
- Measure the water surface elevation
- Inspect the superstructure for lateral displacement
Correct answer: Probe the streambed adjacent to the footing with a rod
Probing with a rod directly determines whether the footing or pile cap is exposed or undermined, providing the most immediate safety-critical data.
Question 7: A bridge bearing that exhibits 'frozen' condition (no movement despite temperature changes) is most likely to cause which secondary defect?
- Fatigue cracks in the bearing sole plate
- Unintended longitudinal forces transferred to the substructure (Correct answer)
- Delamination of the bridge deck
- Corrosion of anchor bolts only
Correct answer: Unintended longitudinal forces transferred to the substructure
A frozen bearing prevents thermal expansion, transferring large unintended horizontal forces to piers or abutments, potentially causing cracking or tilting.
CTQP Structures Inspection 4
During a CTQP structures inspection, which condition in a concrete bridge deck most directly indicates alkali-silica reaction (ASR)?