27.E Lift-Slab Operations.
27.E.01 Lift-slab operations must be planned and designed by an RPE. Lift-Slab Plans and designs must include detailed instructions and sketches indicating the prescribed method of erection and must be submitted to the GDA for review.
Lift-slab operations are being performed on this multi-story structure.
27.E.02 Jacking equipment.
- The manufacturer's rated capacity must be legibly marked on all jacks and must not be exceeded.
- All jacking equipment such as threaded rods, lifting attachments, lifting nuts, columns and other members that transmit loads to the jacks must be capable of supporting at least two and one-half times the load being lifted.
- Jacks must be designed and installed so that they will not continue to lift when overloaded.
- All jacks must have a positive stop to prevent over-travel.
- Hydraulic jacks used in lift-slab construction must have a safety device that will cause the jacks to support the load in any position if the jack malfunctions.
27.E.03 Jacking operations.
- When it is necessary to provide a firm foundation, the base of the jack must be blocked or cribbed. Where there is a possibility of slippage of the metal cap of the jack, a wood block must be placed between the cap and the load.
- The maximum number of manually-controlled jacks on one slab must be limited to 14, and in no event must the number be too great to permit the operator to maintain the slab level within specific tolerances.
- Jacking operations must be synchronized to ensure even and uniform lifting of the slab.
- During lifting, all points of the slab support must be kept within 1/2 in (1.2 cm) of that needed to maintain the slab in a level position.
- (1) If leveling is automatically controlled, a device must be installed which will stop the operation when the 1/2 in (1.2 cm) leveling tolerance is exceeded.
- (2) If leveling is manually controlled, such controls must be located in a central location and attended by a trained operator while lifting is in progress.
- No one must be permitted under the slab during jacking operations.
Knowledge Check Choose the best answer for the question.
27-6. How much weight must jacking equipment that transmit loads to the jacks be capable of supporting?
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