Tallest towers in South America on the Torre Gran Costanera

A pair of luffing jib tower cranes is vital to the construction of South America's tallest tower. IC reports

What will be Latin America's tallest tower, the Torre Gran Costanera, is under construction using a pair of luffing jib cranes

The Liebherr luffers are two of 14 from the German manufacturer helping to construct the US$500 million, 694,000 square metre Costanera Center in Santiago, Chile. Centrepiece of the project is the 70 floor, 300 m tall Torre Gran Costanera.

Project owner Cencosud purchased 12 of the14 cranes from Maquinarias Cruz del Sur SA (MCS), Liebherr distributor in Chile since 2003. MCS has a rental division that supplied the other two units.

The project includes: two hotels, two department stores, office accommodation and a shopping mall with more than 300 shops and a food court.

Initially, Cencosud considered using three tower cranes for the Torre Gran Costanera, explains project director Bernado Hopp but, Liebherr demonstrated that with the correct deployment, two cranes could be just as effective.

According to Hopp the joint decision to use Liebherr HC-L luffing jib cranes for the tallest tower was made to save space. Hopp adds, that their small slewing radii and raised jib angles of 15 to 70 degrees, even when out of service, make the cranes particularly advantageous on sites where space is restricted and there are several cranes with overlapping slewing areas.

Lifting at speed

Both luffing jibs are Liebherr HC-L models. One, a 335HC-L, was anchored to the outside of the tower and will climb to its full height. It has a 55 m jib with 5,500 kg tip load, and a maximum hoisting speed of 170 m/min.

The second, a 224HC-L, is in the elevator shaft and will eventually be dismantled and removed using the 335HC-L. Jib length is 55 m, tip load is 3,200 kg and the maximum hoisting speed is 240 m/min.

Hopp says that the lifting speed was a vital factor on such a large project "because a crane with even a slightly slower lift speed or lower lift capacity would eventually lead to a much longer construction period on such a tall tower."

Lifting speeds and jib lengths were also important factors in selecting the cranes for the other elements of the project. Seven are top slewing models, designed for high load capacity at full reach. Three are 200 EC-H10 Litronic models, with jib lengths of 60 m, tip load capacities of 2,650 kg and a maximum hoist speed of 100 m/min. Two are 200 EC-H10s, with a 55 m jib length, a 2,850 kg tip load, and a 100 m/min hoist speed.

The remaining two cranes are154 EC-H10s, one with a 55 m jib, the other a 60 m jib, and 1,850 and 1,400 kg tip loads, respectively. Both units have a maximum hoist speed of 100 m/min.

Buy-back option

The three other cranes belonging to Cencosud are 90 EC-B6 flat tops with 50 m jibs and 1,500kg tip load. Maximum hoisting speed is 70 m/min.

One of the two Liebherr cranes supplied from the MCS rental fleet is a flat top 99 EC with 50 m jib, 1,600 kg tip load and 103 m/min hoisting speed. The second rental unit is a top slewing 98.3 HC with 50 m jib, 1,500 kg load at jib end and 114 m/min hoist speed.

Chief executive officer of MCS, Raul Montt, says that the two rented units are on the shopping mall construction, which will be the first element of the project to be completed. As soon as the construction work is done, they will be removed.

Montt says that a buy-back option included in the contract for the 12 cranes could see the two luffing jib cranes being re-exported, as their size would give them a limited market in Chile. The other 10 units will join the MCS fleet.

Montt adds that the longest unscheduled shutdown of a crane would be no more than 45 minutes. Routine maintenance on the cables, pulleys, gears and other moving parts is every 200 hours, to help ensure continual functioning at 100 % efficiency.

MCS also uses the Austrian Save A Life (SAL), safety system in which a safety harness is used to bring an operator to ground if they get into difficulty.