Tower Crane Virtual Conference: Infrastructure7 April 2021
Mohamed Abouelezz, general manager sales MENA - South East Asia at Wolffkran, delivered a presentation of the evolution of tower cranes for infrastructure projects.
Abouelezz highlighted the advantages of using tower cranes instead of crawler cranes for these jobs. “Infrastructure projects usually have strict deadlines. That is why operation speed plays an important role, and that is one of the advantages of tower cranes in comparison to crawler cranes.”
He then talked about the tower cranes’ comparative advantage in terms of mobilisation, saying they can be transported more easily to sites in rural areas, where many infrastructure projects are situated.
“Footprint is another important issue that must be considered,” Abouelezz added. “On big infrastructure projects sites there is always limited working area available, so having a large crawler crane there requires a lot of space. For tower cranes all you need is approximately a 6x6m footprint.”
Another advantage of tower cranes cited, was their ability to operate at higher wind speeds than crawler cranes.
At Wolffkran they have seen requirements for high capacity cranes with high freestanding heights for infrastructure projects such as power plants, dams and wind turbines. “We have worked and developed our solutions combining all the demands of infrastructure projects with the experience we have in tower crane design and technology. We developed the TV 60 tower section, Wolffkran’s biggest section, which has a 6x6m base and 5m height,” said Abouelezz.
“This specific tower section the TV60 can freestrand a Wolff 1250B, which has 60t maximum load capacity, up to 130m without any additional tie-in. This tower section weighs around 28t and can be assembled on site. It facilitates transportation, as only around 1.5 trucks are required for transporting one tower section.” The new section can connects to Wolffkran’s smaller TV 33 (3.3x3.3m) section by way of a connection frame.
The first project where the TV 60 sections are being used is the construction of the Spitallamm Replacement Dam at Lake Grimsel in Switzerland, which is approximately 2000m above see levels. The sections will be used for the erection of the 1250B.
Abouelezz also talked about the use of seven Wolffkran tower cranes for the construction of the 4,800MW Kusile coal-fired power station in South Africa.
“The project involved a lot of heavy lifts; many steel structures and a lot of concrete. Loads weighed up to 60t and the space on site was limited, so four Wolff 1250B were deployed.” These units had a 60m jib configuration and 120m tower height and were erected on a 12x12m static cross base. “One of the main challenges of this project was the number of tie-ins required and their design. So for the 120m tower height only one tie-in was fixed at 67m. The frames were developed to fix the tie-ins to the stair tower of the boiler house and the loads taken into consideration in this design were up to 2000kN out of service and that is a very high force. This was developed specifically for this project to keep the ties to minimum.”
Three 28t Wolff 355B were also used for this project; they were erected on top of the boiler structure on a travelling undercarriage with a 6x6m base on rails. All three cranes had 50m jib and only a 9m tower height, but the overall hook height was 187m. “These were traveling on top of the boiler to cover the biggest available radius for both sides of the boiler. The advantages of having the cranes on top were to save space on the ground and to save costs, having 9m tower height instead of 120m saved a lot of time and money.”