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Towers, towers, towers

by Stian Overdahl on May 1, 2013

Wolffkran's tie system, seen on an Al-Futtaim Carillion project in Downtown Dubai. The tallest crane topped out at 203m.
Wolffkran's tie system, seen on an Al-Futtaim Carillion project in Downtown Dubai. The tallest crane topped out at 203m.

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Tower cranes an integral part of any major construction site, and new models and market options can bring improvements and efficiencies to any building job.

While in Dubai there remain significant numbers of tower cranes standing idle on halted projects, overall the anticipated levels of construction in the GCC, in major cities such Abu Dhabi, Riyadh, Jeddah and Doha, indicates that manufacturers and service providers should see steady demand in the medium- and long-term.

Going large
With social and demographic pressures in the Middle East in full focus, construction of infrastructure, including hospitals, school, medium density housing, airports and roads is often prioritised over the tall vanity towers.

One impact for the tower crane industry is that pre-cast concrete is a popular choice for these projects. And as pre-cast has become more common globally, tower cranes have increased in size.

Thilo Stark, marketing and market management at Liebherr-Werk Biberach, says that in general, weight classes are getting higher because more and more prefabricated elements are being used in construction.

With a strong fleet of towers in the Middle East, Stark says that well-utilised Liebherr cranes in the region include the 280 EC-H tower cranes with 12 tonne max capacity, the 160 HC-L luffing jib crane (16 tonne max capacity), as well as the large HC cranes, with a lift weight extending up to 50 tonnes.

Thibaut Le Besnerais, global product direct tower cranes at Manitowoc, sees a trend in the projects underway in less-developed markets that is driving the shift to larger cranes.

“At the moment we are seeing a shift towards bigger cranes. The slower demand in traditional markets, combined with the growing demand for infrastructure work in emerging countries and economies, are driving this.”

In the GCC, Wolffkran’s 8033cross has proven to be a popular model since its release in 2010, effective on job sites with heavy concrete pre-cast elements, with a max lift of 20t and a maximum jib radius of 80m. As many as 60 of the 8033cross machines are in use at the development of the new Jeddah airport.

Flat tops
At last year’s bauma China exhibition in Shanghai, there was no escaping the impression that flat top cranes were everywhere. Easier to transport and assemble, and with closer working distances, it is not hard to see their attractions.

If there is one company that can be counted on to put forward the advantages of flat tops it is Linden Comansa, since it is the company’s entire production range.

“Flat-top tower cranes have much more advantages than tower cranes with pendant lines, because they are safer, much easier to erect, and they save money: in jobsites with many cranes, the flat-top tower cranes don’t need to be erected as high as tower cranes with pendant lines because the interferences between jibs are less,” says their sales director Martín Echevarría.

“All these advantages are making flat-top tower cranes more popular around the world and now almost all manufacturers offer flat-top tower cranes.”

Linden Comansa’ cranes are built with a very strong modularity, says Echevarría, which allows operators to share sections between different cranes, and even different series. Likewise, Besnerais sees clear advantages of flat tops for fleet owners.

“They are easier and faster to erect and dismantle, plus there is less interference when cranes are overflying. Utilising topless cranes can offer significant cost savings on jobs where multiple cranes are needed.”

While some companies are building large capacity flat tops, for others there are recognised size limitations. Stark says that Liebherr reckons with limitations beyond 400 tonne metres.
“For bigger sizes, from our point of view, high top cranes provide significant advantages.”

Wolffkran global product manager Gerd Tiedtke says that the company’s philosophy is to build its clear lines cranes (flat tops) for small and medium load moments, and then jump to its cross line cranes for larger load moments. Clear lines are fine up to roughly 250 mt’s, says Tiedtke, but beyond this the better solution is the ordinary design with braced jib.

“Theoretically” Wolffkran could build a flat top up to 600 mt, he notes, but believes it is inefficient to do so, because of the heavy weight of steel that would be required in the jib required for strengthening.

Additionally, the size of such reinforced jib sections would not allow for easy containerisation for transporting to overseas markets such as the GCC.

Indeed, some of the largest flat-top sections on the biggest cranes need to be transported in open containers.

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