Delivery of tower crane components to site.

For the author, some of the most frequently asked questions about tower crane used in
construction are:
How many types of tower crane are commonly used in building and construction projects
for tall structures?
How is a tower crane erected?
How can a tower crane climb in pace with the ascending of the building structure?
How the crane is dismantled at the rooftop upon the completion of a construction
project?
As most of the major operations in construction, no matter how sophisticated they seem,
there is no sophisticated theory or mysterious magic behind. It is mainly a matter of
whether you know it or not. To understand the subject, what you need is just to see it or to
witness the process. This series of photos are thus specially selected, trying to answer the
above questions.
Delivery of tower crane components to site.
Close up of the major components - a standard section of mast, slewing ring,
control cabin and the winching machine segment (right upper corner).
Erection of the first section of mast of
the tower crane. At the early stage, the
crane is free standing on a mass
concrete pad foundation. It can
"climb" later by disconnecting the
mast from the pad when the building
structure ascends to a higher altitude.
Onward erection of the main mast.
Placing the slewing ring segment to
the top of mast.
Lifting of the cabin module
Lifting Placing of the cabin module.
the cabin module
Pre-fabricating of the jib on a cleared
location on site. This jib measured
more than 25m in length and
composed of 4 standard sections. It is
almost impossible to have them
connected up in the air. The jib will be
connected on ground level and lifted
to the mast top in one piece for easy
and safe erection.
Lifting up of the winching machine
segment.
Connecting the winching machine segment onto the central mast section. Due to
the heavy mass of the winching machine, together with the addition of precast
concrete blocks to the slot at the tip of the platform, this segment usually serves
also as a counter weight to balance the lifting action on the jib side.
The most difficult and dangerous part of the crane erection process - the
articulating of the main jib, fixing of the tie members, and finally the placing-in
of the lifting cables.
The method: for crane of larger size, a smaller tower crane will be
erected with the help of the original crane, which is rested or
anchored firmly on the newly completed rooftop, and with its weight
carefully spread even on the roof structure. The new crane will help
to dismantle the original crane and to lower the components down to
street level afterward. Upon the completion, a simple derrick-type
static crane or a hoisting rod system operated using winching
machine will be installed, which serves to dismantle the smaller crane
similarly to the original one. The derrick crane or hoisting rod is made
of small articulating sections for easy handling and dismantling
reasons. This process may be required to repeat once again by a even
smaller set of winching equipment if the original crane is a very big
one.
The "soon-be-dismantled" crane helps to erect a smaller crane, which will be used to
dismantle the original crane afterward. Note that in this photo, the crane is a what it calls
"luffing crane". One obvious feature of which is the tiltable jib, that can be slung upward
to minimize its turning radius.
The original crane (the red one) and
the smaller crane for dismantling the
original. Note the footing of the
smaller crane composing of layers of
standard I-beam sections. Usually,
simple shoring system will also be
erected underneath the roof slab so
that the weight of the crane can be
adequately spread and supported.
Sections of the winching equipment being lifted to the roof by the second crane for later
dismantling of the second crane.
A simple derrick-type winching equipment being erected. The yellow crane on the
background is "second crane" pending for dismantling.
Tower crane can be internally or externally mounted. Climbing
action can be made using hydraulic lifting of the entire mast, or by
extending the length of the mast by inserting additional mast
sections as the building structure ascends.
The mast of a 500 ton-m capacity
tower crane being mounted and
secured by heavy universal beam
sections within the shaft of core wall.
A similarly crane being mounted
inside the structural steel frame in
"The Center" project.
Detail of mounting of the crane within
the structural steel frame inside the
"Center" project.
An externally mounted crane used in
typical housing project of the Housing
Authority
To mount the tower crane securely to
the building structure, at least 2 sets of
clamping devices that arranged of
steel beam sections should be
provided to grasp and station the
mast of crane. The photo shows
clearly the arrangement of the
mounting.
The perfect location to position an
internally mounted crane is the lift
shaft or other structural openings, that
have the void already in place as well
as they are usually structurally strong
enough for the imposed load of crane.
However, sometimes it may be
required to locate the crane on usual
floor slab position as the one shown
here. It may be possible subject to
additional strengthening provisions
and approval of project structural
engineer. Note also the reinstatement
of the floor slab at the lower floors.
Fitters working inside the lift shaft
where the tower crane is mounted
preparing for the soon lifting
arrangement of the crane.
Close up detail showing the clamping
devices and the built-in hydraulic jack
system of the crane. The steel bar with
rectangular slots is used to transfer the
jacking action produce by hydraulic
rod, stroke by stroke, to push the
crane upward.
A typically external mounted crane
used for the construction of the bridge
tower for Ting Kau Bridge on the
Tsing Yi Island side.
The standard mast module is ready
for the insertion into the main mast
through the external climbing device.
Close up detail of the main mast, the external climbing device module and the hydraulic
jack arrangement.
Line drawing showing the typical construction of a static tower crane with an external
climbing device.