(1) Lift-slab operations must be designed and
planned by a registered professional engineer who has experience in lift-slab
construction. You must implement such plans and designs and they must include
detailed instructions and sketches indicating the prescribed method of
erection. These plans and designs must also include provisions for ensuring
lateral stability of the building/structure during construction.
(2) Jacks/lifting units must be marked to
indicate their rated capacity as established by the manufacturer.
(3) You must not load jacks/lifting units
beyond their rated capacity as established by the manufacturer.
(4) Jacking equipment must be capable of
supporting at least two and one-half times the load being lifted during jacking
operations and you must not overload the equipment. For the purpose of this
provision, jacking equipment includes any load bearing component which is used
to carry out the lifting operation(s). Such equipment includes, but is not
limited to, the following: Threaded rods, lifting attachments, lifting nuts,
hook-up collars, T-caps, shearheads, columns, and footings.
(5) Jacks/lifting units must be designed and
installed so that they will neither lift nor continue to lift when they are
loaded in excess of their rated capacity.
(6) Jacks/lifting units must have a safety
device installed which will cause the jacks/lifting units to support the load
in any position in the event any jack/lifting unit malfunctions or loses its
lifting ability.
(7) Jacking
operations must be synchronized in such a manner to ensure even and uniform
lifting of the slab. During lifting, you must keep all points at which the slab
is supported within 1/2 inch of that needed to maintain the slab in a level
position.
(8) If leveling is
automatically controlled, a device must be installed that will stop the
operation when the 1/2 inch tolerance set forth in subsection (7) of this
section is exceeded or where there is a malfunction in the jacking (lifting)
system.
(9) If leveling is
maintained by manual controls, such controls must be located in a central
location and attended by a competent person while lifting is in progress. In
addition to meeting the definition in WAC
296-155-012(4),
the competent person must be experienced in the lifting operation and with the
lifting equipment being used.
(10)
You must limit the maximum number of manually controlled jacks/lifting units on
one slab to a number that will permit the operator to maintain the slab level
within specified tolerances of subsection (7) of this section, but in no case
must that number exceed 14.
(11)
You must not permit any employee, except those essential to the jacking
operation, in the building/structure while any jacking operation is taking
place unless the building/structure has been reinforced sufficiently to ensure
its integrity during erection. The phrase "reinforced sufficiently to ensure
its integrity" used in this subsection means that a registered professional
engineer, independent of the engineer who designed and planned the lifting
operation, has determined from the plans that if there is a loss of support at
any jack location, that loss will be confined to that location and the
structure as a whole will remain stable.
(a)
Under no circumstances, must you permit any employee who is not essential to
the jacking operation to be immediately beneath a slab while it is being
lifted.
(b) For the purpose of
subsection (11) of this section, a jacking operation begins when a slab or
group of slabs is lifted and ends when such slabs are secured (with either
temporary connections or permanent connections).
(c) Employers who comply with Appendix A to
WAC
296-155-694 are considered to be
in compliance with the provisions of subsections (11) through (11)(c) of this
section.
(12) When
making temporary connections to support slabs, you must secure wedges by tack
welding, or an equivalent method of securing the wedges to prevent them from
falling out of position. Lifting rods may not be released until the wedges at
that column have been secured.
(13)
All welding on temporary and permanent connections must be performed by a
certified welder, familiar with the welding requirements specified in the plans
and specifications for the lift-slab operation.
(14) You must not execute load transfer from
jack/lifting units to building columns until the welds on the column shear
plates (weld blocks) are cooled to air temperature.
(15) You must positively secure jacks/lifting
units to building columns so that they do not become dislodged or
dislocated.
(16) Equipment must be
designed and installed so that the lifting rods cannot slip out of position or
you must institute other measures, such as the use of locking or blocking
devices, which will provide positive connection between the lifting rods and
attachments and will prevent components from disengaging during lifting
operations.
Appendix to WAC
296-155-694 -Lift-slab
operations
(This appendix is nonmandatory.)
In WAC
296-155-694(11),
WISHA requires employees to be removed from the building/structure during
jacking operations unless an independent registered professional engineer,
other than the engineer who designed and planned the lifting operation, has
determined that the building/structure has been sufficiently reinforced to
insure the integrity of the building/structure. One method to comply with this
provision is for the employer to ensure that continuous bottom steel is
provided in every slab and in both directions through every wall or column head
area. (Column head area means the distance between lines that are one and one
half times the thickness of the slab or drop panel. These lines are located
outside opposite faces of the outer edges of the shearhead sections-See Figure
1.) The amount of bottom steel must be established by assuming loss of support
at a given lifting jack and then determining the steel necessary to carry, by
catenary action over the span between surrounding supports, the slab service
dead load plus any service dead and live loads likely to be acting on the slab
during jacking. In addition, the surrounding supports must be capable of
resisting any additional load transferred to them as a result of the loss of
support at the lifting jack considered.
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Figure 1-Column Head Area
