Debut for weathering grade hollow sections in spectacular observation tower

Since April, the Danish Sealand region has a new highlight in several ways. At 135m above sea level, the new observation tower in the high ropes park of Camp Adventure is now the highest point in the region. At the same time, the hourglass-shaped construction made of weathered hollow sections and local oak wood, designed by Effekt Architects and engineering firm Arup, represents an impressive construction in harmony with the surrounding natural environment. The opening was also a highlight for Tata Steel: the corrosion-resistant hollow sections Celsius weathering grade was used for the first time in a steel structure.

The hollow sections form the supporting structure for the 45m high tower in the forest of Gisselfeld Kloster near Haslev. The bottom and the top are particularly wide and the central part much slimmer. For this shape called hyperboloid, the vertical tubes in the tower were rotated by 120º, thus providing the constricting effect reminiscent of an hourglass. This shape not only increases stability, but also makes the spiralling ascent over the 600m long walkway inside the lattice tower an experience that plays with the changing distance between the walkway and the surrounding area. Due to the gentle ascent the path is accessible for everyone and also suitable for wheelchairs or pushchairs. Once at the top you can enjoy a 25 km wide view over the landscape.

The weathered hollow sections make the construction particularly durable and maintenance-free and, with their reddish-brown colour, fit well into the forest. Compared to conventional structural steels, the low-alloy steel – equivalent to the well-known Corten steel – forms a dense patina on the steel surface due to chemical additives of copper and chrome. This significantly slows down corrosion and thus extends the service life enormously. The natural-looking material is used in particular for infrastructure projects, buildings in nature and frequently in outdoor art installations. It is not necessary to apply or maintain a coating or zinc layer, which has a positive effect on costs. Eliminating the need for re-coating for an extended life, this is a great advantage, especially for areas that are difficult to access.

“This is the first time that the excellent corrosion resistance of weathering steel has been combined with the technical advantages of our true hot-finished premium hollow sections, such as dimensional accuracy, low internal stresses, lower weight and good weldability. Celsius weathering grade provides an excellent basis for the construction of long-lasting, high-performance and low-maintenance structures that are extremely sustainable due to the elimination of further coatings and later maintenance – especially when looking at the entire lifecycle,” said Graeme Peacock, marketing manager at Tata Steel.

Celsius weathering grade is Tata Steel’s response to the increasing demand for weathering steel for durable and resource-saving structures where ongoing maintenance would be difficult to implement. Until now, however, the availability of weathered hollow sections has been very limited, and they could therefore only be used rarely. With the introduction of the new Celsius weathering grade, this gap can now be closed. With a large selection of 298 different dimensions of square, rectangular and circular steel hollow sections in the range, planners and architects can now even better implement durable, low-maintenance construction models.

In addition to the sustainability aspect of weather resistance, Celsius weathering grade, like all other hollow sections from Tata Steel, is certified to BES 6001 for “Responsible Sourcing”. Tata Steel is also considered one of the pioneers in Life Cycle Assessment (LCA) and its Environmental Product Declaration (EPD) program supports architects and planners in meeting the requirements of increasingly stringent certification systems for buildings.