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2011-03-01

Tree Tower in Bavarian Forest, Germany

The path leading through forest treetops in the Bavarian Forest National Park in Germany has a total length of 4,265 ft and is the longest treetop walk worldwide.

The treetop walkway leads to the spiral structure of the egg‑shaped tree tower with a height of 144.3 ft.

Architecture and Structural Analysis

The egg-shaped tree tower was built around three trees with a height of up to 124.6 ft, growing on a rock formation.

In this way, visitors are able to follow the trees' individual steps of growth. Reaching the two-story steel platform at the tower top, they can enjoy the view across the national park.

The tower's principal supporting structure, built mainly of timber, consists of 16 larch glulam beams, which are curved and arranged in rotational symmetry. The upper part of the tower was stiffened by a tight mesh of diagonal steel bars, while the lower part was stiffened by four compression- and tension-resistant crosses consisting of steel hollow sections, which were anchored to the timber arches.

The spiral timber structure is attached to the timber arches by steel suspensions and secondary steel beams. The structural system was calculated according to the second-order analysis.

The calculation resulted in a compression force of 260.79 kips within the timber arches and a maximum horizontal tower deformation of 61.8 in.

The egg shape of the structure required the use of a program that is able to calculate spatial frameworks. We decided to work with the Dlubal program RSTAB, which is best suited for such a challenge,” says Ralf Kolm, the engineer at the WIEHAG company who was responsible for the structural analysis.
Location Baumwipfelpfad Bayerischer Wald
Böhmstraße 43, 94556 Neuschönau, Germany
Structural Engineering Project, Structural Analysis and Construction
WIEHAG GmbH
Altheim, Austria
www.wiehag.com
Architect Josef Stöger, Schoenberg, Germany
stoeger-koelbl.de
Investor Erlebnis Akademie AG, Bad Kötzting, Germany
www.eak-ag.de/eakag


Project Specifications

Model data

Number of Nodes 1460
Number of Members 2337
Number of Load Cases 10
Number of Load Combinations 72
Number of Result Combinations 5
Total Weight 244.606 tons
Dimensions 115.9 x 115.9 x 148.82 feet
Program Version 8.01.00

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