21.09.2017 Custom-tailored formwork solutions from Hünnebeck for premium fair-faced concrete
With a mixture of advanced system formwork and hand-crafted custom formwork elements, Porr Deutschland GmbH has constructed the shell of the almost 44,600 m² gross storey space of the Zalando headquarters in Berlin on behalf of a project company belonging to Münchner Grund Immobilien Bauträger GmbH, a subsidiary of Austria's UBM Development AG. Hünnebeck devised the shuttering strategy for this ambitiously timed mega project which, apart from a few exceptions, requires Category 3 fair-faced concrete on the walls and ceilings.
HENN, the Munich-based firm of architects, designed the two seven-storey buildings of the new Zalando headquarters (Building A rental space around 28,000 m², Building B rental space around 13,000 m²). The centerpiece is an open atrium that extends over seven storeys and directs daylight right down to the open areas on the ground storey of the main building. The central lobby is flanked by stairs with seating and lounge areas that are also suitable for staging events.
Modern systems for modern buildings
Innovative and flexible: what's true of the future Zalando headquarters also applies to the Hünnebeck system solutions used for this in-situ concrete project. The innovative Topmax steel-frame table form ensures particularly quick shuttering and transfer times when producing the slabs on this large construction site, while the advanced Platinum 100 wall formwork system allows the wall surfaces - most of them close to 3.40 m in height - to be shuttered without extensions and concreted extremely fast. Both systems are the utmost in efficiency since the time and costs entailed in setting and transferring the wall and slab forms are reduced to a minimum.
The crane-tied Platinum 100 formwork system scores on a number of counts on this Berlin construction site: for example, with a consistently high pressure resistance of 100 kN/M². The extremely sturdy Platinum 100 system panels (14 cm steel frame) allow walls up to 3.60 m in height to be poured in a single go without speed restrictions. This is a valuable advantage for the shell builders on the Zalando site since the walls are mostly 3.36 m in height.
Another innovative feature is the tying system which, given the shuttering heights of up to 3.60 m, is a time-saving factor and requires 30 percent fewer ties than conventional systems, besides permitting one-sided operation by just a single person for incremental cost and time savings. Platinum 100 comes with a premium-quality solid plastic Ecoplus lining, which minimizes cleaning and maintenance work while delivering a concrete surface of consistently impeccable quality. So the specified Category 3 fair-faced surface is achieved with only a little reworking. Available on the site are around 2,000 m² of long-life Platinum 100 which, since construction start-up in November 2016, have been helping to keep work well on schedule.
The same applies to the altogether 6,000 m² of Topmax table forms designed for quickly shuttering soffit surfaces up to 50 cm thick (maximum ceiling height 5.5 m, with extension frame 7.5 m). This system has likewise fulfilled the expectations of the site team in every respect. Especially impressive are the quick stripping and transfer cycles made possible by simply joining in each case two tables with a centering panner as well as the straightforward combination of shuttering table with system panels that can be manually handled, or the squared timber for infilling and adjusting in no time at all.. The multifunctional connecting options on the steel frame offer even more advantages. Combined with Hünnebeck Protecto protection equipment against falling, the construction workers can quickly and safely produce slab edge tables which are raised by crane as a complete unit, including side protection to the next working level. The construction site workers are appreciative: "During our day-to-day work we've very quickly realized that these innovative systems match and coordinate in the tiniest practical detail to make our work that much easier."
Custom formwork solutions made by Hünnebeck
So much regarding the system formwork used on the site and classified as standard by the Hünnebeck engineer heading the project. The highlight of the project was the development and provision of the custom formwork for producing the curved parapets in the atrium. After a number of surfaces had been sampled, the site team opted for beam formwork elements lined with plastic to be used for the elements of the some 900 linear meters of parapets. The elements were manufactured at Hünnebeck's own formwork shop. To ensure the most efficient use of this custom formwork, the planners developed standard elements 2.5 m in length which, depending on the parapet length, were combined with longer or shorter fill-in elements. The use of the premium shuttering panel ensures visual harmony with the adjoining staircase cores made with Platinum 100. All the parapets are rounded at the corners. To this end, Hünnebeck engineers provided shuttering elements with bent ribs and curved lining.
There's another practical aspect covered by the Hünnebeck approach to the construction of the atrium. The fall-safe slab tables pointing to the atrium always protrude far enough to accommodate the custom formwork elements, allowing the exterior elements of the custom formwork to serve as slab edge formwork, which is why they are 30 cm higher than the 120 cm interior elements. This is how the construction site team describes this time-saving approach: "First of all, we set up the exterior elements, we then pour the 30 cm thick slab, leave the exterior elements standing, place the interior elements in front of these and can then immediately begin work on concreting the parapet. This is both quick and very safe."
The formwork planners' idea of leaving the Topmax tables in place to serve as a kind of falsework over several storeys in a number of ceiling corner areas is just as safe and efficient. Why? The protrusion of the ceilings and thus of the parapets into the open space of the atrium varies from storey to storey, in some cases further, in others less. Therefore, for the first and second storeys, the plan is to set up the slab formwork for the first storey in full projection on a space of around 600 m², even though the parapet retreats at this point, and then mount on this the tables for the second-storey slabs. This provides a safe working platform without a scaffold having to be mounted.
"Such carefully thought-out details make our work much easier, of course. They save time and wage costs. We feel very well taken care of," comment the site workers on the successful strategy. The Hünnebeck engineer in charge adds: "Our uppermost goal on any project is to work out the best possible solutions to all the shattering challenges together with the site workers. There's no such thing as an off-the-peg solution. The conditions must be freshly explored and assessed for each and every project. Only then can we come up with a truly customized shuttering strategy."
Hünnebeck Deutschland GmbH
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