Dusseldorf – July 2019. The city of Dusseldorf along the Rhine is rapidly growing upwards. One of the most spectacular projects in this respect is the Rhein 740 Tower, a 21-story apartment and medical services building currently under construction on the former site of the Dominikus Hospital in the district of Heerdt on the left bank of the Rhine overlooking Dusseldorf’s Old Town. GWI Bauunternehmung GmbH, commissioned with the construction, is using two WOLFF flat-top cranes to build this striking high-rise with its organic-looking façade located at the eponymous Rhine kilometer 740.
Freestanding with a height under hook of almost 100 meters
The flat-top WOLFF duo comprises a WOLFF 7534.16 and a WOLFF 6015.8 with respective jib lengths of 50 meters and 37.5 meters. “Since the cranes cannot be tied to the building due to the situation on site, they have to work freestanding despite substantial heights under hook of 93.3 meters and 82.5 meters respectively,” said Carsten Druske, Head of Rental Germany and Branch Manager of WOLFFKRAN Dortmund, highlighting one of the primary project challenges. In order to nonetheless provide the required stability for lifting formwork and concrete components as well as the extravagant facade elements, both cranes were mounted on a foundation anchor embedded in concrete. The higher assembled WOLFF 7534.16 additionally features a stable BT 29 WOLFF tower section with external dimensions measuring 3 x 3 meters at the base of the tower.
Custom-made climbing concept
To save time and money as well as negotiate the tight space on the site between Pariser Strasse and the left bank of the Rhine and close proximity to a nearby hospital, the WOLFF team opted for an assembly concept based on the teamwork principle. A first step saw a 250-ton mobile crane assemble the WOLFF 7534.16 to a height under hook of 48.30 meters. Next, the already operational tower crane assembled the smaller WOLFF 6015.8 to a basic height under hook of 37.5 meters. Both assembly maneuvers were completed within a day. When structural work on the high-rise reached a height of around 40 meters, the WOLFF 7534.16 was climbed to a final height under hook of 93.3 meters and in turn used to bring the WOLFF 6015.8 up to its final height. This was done by disassembling the entire slewing unit, adding more tower sections to the existing tower and finally reinstalling the slewing unit.
Thanks to the custom-made assembly concept of one crane erecting the other, the use of mobile cranes was kept to a minimum and roadblocks around the adjacent Schön Clinic avoided.
Getting to work in the lofty heights safely and quickly
To shorten the times for ascent and descent and spare the crane operator energy-sapping climbs, the higher standing WOLFF 7534.16 is equipped with an elevator, which would also be used to safely rescue the operator in an emergency situation.
Once the building was structurally complete, the WOLFF 6015.8 was dismantled while the WOLFF 7534.16 remains on the project to help finish the building work.
The by now well-established cooperation between GWI Bauunternehmung GmbH and WOLFFKRAN continues in the form of the Upper Nord Tower project – this time located on the right bank of the Rhine. Three flat-top WOLFF cranes (WOLFF 7534, WOLFF 6020, WOLFF 5020) will be in operation to construct a 120-meter-high apartment block, the highest in the North Rhine-Westphalian capital.