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climbed until it reached a final height of

195.6 metres.

As well as the land-based crane, this crane

needed four ties to the pylon to ensure

that it could work without a problem at

such impressive height.

The work of the cranes, both with max-

imum load capacity of 18 tonnes, consisted

in the lifting of all the pylons’ steel struc-

tures and concrete, and afterwards, the

lifting of the cables that support the deck

of the bridge.

The 110 kW hoisting engines allowed

the cranes to work at a great speed and

efficiency during these 8 years.

During the works, a change in the design of the metal

anchors that attach the cables to the pylons forced

Linden Comansa’s engineering team to quickly find a

solution to an important although unexpected

situation.

The anchors, which initially had to weigh less than

18 tonnes to be elevated and fit into place by the cranes,

became pieces of more than 23 tonnes.

Dragados used a very large mobile crane for placing

the anchors on the pylon located ashore, something that

was impossible for the pylon located in the sea.

In this instance, so that the crane could load these

anchors, Linden Comansa’s R & D department had to

review and reinforce the crane’s kinematics (pulleys,

trolley/hook set, hoisting cable, etc.) and counterweights.

This enabled the 21LC400 to lift this "extra" load in a

timely manner and under the supervision of technicians

from Eleva Grúas Torre.

Disassembly, the greatest challenge

Once the Linden Comansa tower cranes ended their

tasks in the summer of 2015, the Eleva Grúas Torre team

had to face the removal. While both cranes had been

erected with the same configuration, different setbacks

appeared in their take-downs.

The crane in the middle of the bay was the first to

be removed once the most important works on the

bridge were completed.

The crane had four ties to the pylon, with the highest

one a weight of 10 tonnes and a length of 23 metres.

Removing it with a mobile crane was impossible due the

height and the presence of the bridge cables, so the

tower crane itself had to take care of this manoeuvre.

The crane had already been jacked down some tower

sections and when it was time to slew, an interference

arose between the boom of the crane and pylon, so it

was necessary to remove several jib sections.

An articulating crane, located at the top of the pylon

for future bridge maintenance tasks, was used for such

duties.

This crane removed jib sections and counterweights

in a sequential way and placed them at the top of the

pylon so that the tower crane could lower them down

to the deck of the bridge.

Thus, it was possible to reduce the jib from 50 to 20

metres, and with this reach the tower crane was able to

rotate freely and remove the bracing by itself.

The crane installed on land was erected closer to the

pylon in comparison to the one in the middle of the

water.

When it came to remove the jib sections of the tower

crane, the articulating crane located at the top of the

pylon was not able to reach the jib-end.

It was necessary to use a jib section dismantling

device, designed by Linden Comansa’s engineering team,

to reduce the jib length of the 21LC400 from 50 to 30

metres (two sections).

With this new configuration, the articulating crane

was able to dismantle the last jib section and leave the

crane with a reach of 20 metres.

However, to achieve this jib-length reduction, it was

necessary to study a new disassembly sequence, move

the trolley winch 20 metres through the boom, and

change the jib end.

Finally, the 21LC400 was able to remove the ties 4

and 3, leaving the lowest two to a mobile crane, which

had to remove them by placing its boom between the

cables of the bridge.

According to Rodrigo García, head of Eleva Gruas

Torre’s erection team, the removal of both cranes was

complicated, but was done very efficiently:

"We jacked down and dismantled the crane

installed in the middle of the bay in just 21

working days of work, when we had raised

possibilities of more than 30 days.

" In the case of the 21LC400 located inland,

it took just 17 days, even though we had several

days in which the weather hindered our work".

• cw

Contractors World International

Contractors World International Vol 7 No 1

25