CPC CPC Construction Equipment & Temporary Structures 1 — Questions and Answers
Question 1: What is the primary factor that determines a crane's rated lifting capacity at a given radius?
- Engine horsepower
- Boom angle and load radius (Correct answer)
- Track or tire pressure
- Hydraulic fluid temperature
Correct answer: Boom angle and load radius
A crane's rated capacity decreases as the load radius (horizontal distance from center of rotation to load) increases due to increasing overturning moment.
Question 2: Which excavation support system uses horizontal steel members braced against the trench walls with no external tiebacks?
- Tie-back wall system
- Braced cut (internally braced excavation) (Correct answer)
- Slurry wall
- Soldier pile and lagging
Correct answer: Braced cut (internally braced excavation)
A braced cut uses internal struts or cross-lot bracing between opposite trench walls to resist lateral earth pressure without external anchors.
Question 3: What is the maximum safe working angle for a suspended scaffolding rope on a swing stage scaffold?
- No more than 15 degrees from vertical (Correct answer)
- Up to 45 degrees from horizontal
- Exactly 90 degrees to the face
- No more than 30 degrees from vertical
Correct answer: No more than 15 degrees from vertical
OSHA requires suspension ropes on two-point (swing stage) scaffolding to be plumb (vertical) or no more than 15 degrees from vertical to prevent swinging.
Question 4: A tower crane's 'out-of-service' wind speed rating is important because:
- It sets the maximum concrete pour volume
- It defines the wind speed at which the crane must be weathervaned and unloaded (Correct answer)
- It determines the crane's maximum lifting height
- It establishes daily lubrication intervals
Correct answer: It defines the wind speed at which the crane must be weathervaned and unloaded
Out-of-service wind speed ratings define when a tower crane must be placed in free-slew (weathervane) mode with no load to reduce wind-induced forces.
Question 5: What is the purpose of a 'shoring' system in below-grade construction?
- Provide temporary electrical power
- Temporarily support loads above while permanent structure is built below (Correct answer)
- Direct groundwater flow
- Compact backfill
Correct answer: Temporarily support loads above while permanent structure is built below
Shoring provides temporary vertical support for structural loads above an excavation while the permanent foundation or structure is constructed below.
Question 6: Which type of dewatering system lowers the groundwater table by pumping from a series of closely spaced small-diameter wells connected to a header pipe?
- Sump pumping
- Wellpoint system (Correct answer)
- Electro-osmosis
- Deep well drainage
Correct answer: Wellpoint system
A wellpoint system uses closely spaced shallow wells connected to a vacuum header, effectively lowering the groundwater table across the entire excavation area.
CPC CPC Construction Equipment & Temporary Structures 1
What is the primary factor that determines a crane's rated lifting capacity at a given radius?