Handling, Storage, Shipping, and Safety
What this domain tests
This domain tests lifting, rigging, storage, stacking, transport, and worker safety for precast/prestressed units. Questions often involve load calculations, lifting-point use, and safe behavior around tensioned strand.
Core rules
- Lift only at designated points using approved inserts, slings, spreader beams, and hardware. Verify rigging capacity and inspection status.
- Account for dynamic load and sling angle. Sling tension increases as the angle from horizontal decreases.
- Store units on firm, drained ground with dunnage at approved bearing points. Prevent twisting, point loading, and unstable stacking.
- Protect units during transport with proper bracing, tie-downs, and clearance checks. Do not use strand as a tiedown point.
- Safety around prestressing is strict: use shields, exclude personnel from behind jacks, and follow the approved strand-cutting sequence. Use PPE and controlled access zones.
Worked example
A 12,000 lb member is lifted by two symmetric slings at 60 degrees from horizontal. Each sling carries half the vertical load, 6,000 lb. Tension = 6,000 / sin 60 = 6,928 lb. With a 1.25 dynamic factor, the required rigging rating is 6,928 x 1.25 = 8,660 lb per sling. The rigger selects hardware above that rating and verifies the sling angle in the lift plan.
Traps
Using the angle from vertical instead of horizontal; ignoring dynamic load; lifting at non-designated points; storing on soft ground; and cutting tensioned strand without shielding.