Mark Sovocool, engineering
manager, Mr. Crane, said: “The
track system is a typical Liebherr
bogie and track system, with
electrically driven bogies. What
is un-der the track is anything
but typical. We came up with
a block system, with blocks
designed by Coreslab Structures
(LA) Inc., to support the track and
crane that can be easily removed
once the project is complete.”
Traversing the roof
The tracks sit on two rows of 20,000-lb.
concrete blocks extending approxi-mately
100 yards across the top of the parking
garage. The temporary shoring col-umns
and wireless load indicating compression
load cells are moved across the parking
garage below as the crane transverses the
roof top overhead.
John Molidor, general manager,
Straightpoint Inc., said: “A sampling of the
shoring column loads is provided by 40
wireless 10 ton compression load cells.
The wireless load data is transmitted to a
Windows PC (or tablet) running our SWMWLC software. The software’s web server
function transmits the real time load da-ta
via a local area network to the tower crane
operators high above, allowing them to
view the live loads on mobile technology
such as an iPhone or Android device. Our
SMS alert system is employed to monitor
the loads associated with the cranes.
Maximum load thresholds are established
and if reached key engineers and project administrators will be automatically
notified via email and text of the alarming
conditions.”
Sovocool added: “It is important to
monitor loads so we can check there is a
good distribution of force onto all of the
shores in the immediate vicinity of the
crane. The load cells allow our personnel
to walk around the shoring posts and get
wirelessly live readings of the force under
a sampling of the shore posts, giving us
some idea as to what the posts are actually
seeing as the crane swings, and in some
cases travels. The goal was to ensure that
no single post was overloaded.”
The whole project is a remodel and
expansion of the mall. It involved clearing
existing structures on the top floor (shops),
reinforcing structural components and
erecting steel for the new sections of the
mall. Typical loads are below 20,000 lbs.,
with some critical lifts up to 42,000 lbs.
The mobile cranes have been removed
from the project, but all three tower cranes
remain. The load cells on the two garage
supported tower cranes are still in place.