AR 4B AR 493 BT - 5 NEUST
LIFT SLAB
CONSTRUCTION
SYSTEM
AR 4B AR 493 BT - 5 NEUST
AR 4B AR 493 BT - 5 NEUST
TABLE
of contents
01. Introduction 04. Construction Sequence
02.Historical Background 05. Advantages and
03. Equipments used for Lift Slab Disadvantaes
INTRODUCTION
Lift-slab construction is a method of construction
where the concrete floors and roof slabs are cast on
top of one another at ground level and then are lifted
into their final position by means of hydraulic jacks.
This construction technique is used in hotels, parking
garages, office buildings and apartments. This method of
construction allows for a large portion of the work to be
completed at ground level, negating the need to form floor
work in place. The ability to create monolithic concrete
slabs makes the lift slab construction technique useful in
quickly creating structures with repetitive form work, like
parking ramps.
INTRODUCTION
Lift slab can be used for heights up to about 16
stories. Economical column spacing ranges from 22 to
32 feet. Columns may be pipe, tubes, or wide flange
sections; concrete columns may be used in 3- to 4-
story buildings.
HISTORICAL
BACKGROUND
The method was invented and developed in the
early 1950s by a collaboration of Philip N. Youtz
and Thomas B. Slick. resulting Youtz-Slick Lift-
Slab Method of Construction. Johnstone Hall, a
Clemson University dormitory in Clemson, South
Carolina, was erected using this method in 1954.
Lift slab construction was also involved in the
L'Ambiance Plaza collapse in Bridgeport,
Connecticut, in 1987, and resulted in a
nationwide federal investigation into this
construction technique in the United States, and
Connecticut imposed a temporary delay on lift
slab construction. Johnstone Hall, Clemson University
YOUTZ-SLICK LIFT-SLAB METHOD
WHAT ARE THE
EQUIPMENT USED
FOR LIFT SLAB?
01 02
This jack is a hydraulic piece of equipment which has positive safety devices
on it. The jack can lift slabs on columns loaded up to 100,000 pounds at
speeds of up to 14 feet an hour.
01 HYDRAULICC JACKS
01 02
Lifting collars are cast into each slab around each column providing a means to
lift the slab and also providing shear reinforcement, they are fixed to columns
by welding shear blocks to plates welded column flanges and to the collar
after the slab has been raised in position.
02 OLLARS
LIFTING COLLARS
01 02
It is steel component used to hold the lifted slab in its final elevation.
03 SHEAR BLOCK
01
The main function of bond breakers is to minimize dynamic loads during lifting
or stripping of precast members and permit their complete, clean separation
from casting slabs or molds. In lift-slab construction bond-breaking
compounds permit the slabs to be separated cleanly and easily from one
another. Bond breakers include wax dissolved in a volatile spirit, polythene
sheet or building paper may also be used as an alternative.
04 BOND BREAKER
REAKER
CONSTRUCTION SEQUENCE
The sequence of lifting slabs is influenced by the following factors:
Weight of the slab
Height of the building.
Lifting capacity of jacks.
Cross sectional area of columns during initial lifting.
CONSTRUCTION SEQUENCE The first-floor slab is cast
When it has matured it inside edge form work on top
The steel or concrete is sprayed with two or of the ground floor slab and
columns are first put position three coats of a when it is mature it is in turn
and rigidly connected to the separating medium Lifting collars are cast coated or covered with the
foundation then the ground consisting or what is into each slab around separating medium and next
floor slab is cast. called bond breaker. each column. floor slab in cast on top of it.
01 02 03 04
05 06 07
The casting of the other slabs The slabs are lifted by jacks, operating A central control
continues until all the floors on the top of each column, which lift a synchronizes the process for
and roof have been cast one pair of steel rods attached to each lifting a uniform lift from all
on the other on the ground. collar in the slab being raised. directions.
YOUTZ-SLICK LIFT-SLAB METHOD
WHAT ARE THE
ADVANTAGES AND
DISADVANTAGES
OF LIFT SLAB?
YOUTZ-SLICK LIFT-SLAB METHOD
ADVANTAGES
·THE ONLY FORMWORK REQUIRED IS TO THE EDGES OF THE SLABS AND
NO CENTERING IS REQUIRED TO THE SOFFIT OF THE SLABS.
·THE SLABS ARE CAST MONOLITHICALLY AND CAN BE DESIGNED TO
SPAN CONTINUOUSLY BETWEEN THE POINTS OF SUPPORT AND SO
EMPLOY THE LEAST THICKNESS OF SLAB.
LIFT-SLAB CONSTRUCTION METHOD BECOMES MORE ADVANTAGEOUS
IN BUILDINGS WITH SIMILAR FLOOR PLANS THROUGHOUT THE
HEIGHT OF THE BUILDING AND WHERE FLUSH SLAB MAY BE DESIRED.
·LIFT-SLAB METHOD MAY BE EMPLOYED WITH RIBBED SLABS NOT
ONLY FLAT SLABS WITH SOME COMPROMISE OF THE EASE OF
CASTING.
YOUTZ-SLICK LIFT-SLAB METHOD
DISADVANTAGES
·IF NOT PROPERLY HANDLED, THE PRECAST UNITS MAY BE DAMAGED
DURING TRANSPORT.
·IT BECOMES DIFFICULT TO PRODUCE SATISFACTORY CONNECTIONS
BETWEEN THE PRECAST MEMBERS.
·IT IS NECESSARY TO ARRANGE FOR SPECIAL EQUIPMENT FOR
LIFTING AND MOVING OF THE PRECAST UNITS.
YOUTZ-SLICK LIFT-SLAB METHOD
THAT’S ALL,
THANK YOU.
