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Helsinki Zoo
Korkeasaari Island
Helsinki

Finland
coordinates: lat 60.1738281, long 24.9801102

Building names(s): Helsinki Zoo Lookout Tower

Architect/Designer: Ville Hara
architect website:

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Last modified: 3 June, 2009 | Suggested By kiwi kid

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1. on 23 Apr 2009 DETAIL

   The tower was the outcome of an international student competition and was to stand in a prominent position high above the sea. The prizewinners justified the free curves of their design by arguing that they had a greater affinity to man and nature and were more economical than rectilinear forms. In order to avoid problems in implementing the scheme, there was a protracted trial phase, with 3-D simulations and models. The finely articulated, self-supporting net-like structure of the tower consists of 72 curved wood strips. After extensive tests, it was decided to have these
   6 ? 6 cm laminated members bent to seven different radii at works and to shape them to their final curvature by steam treatment on site. The members were simply bolted together and braced in part with nailed plates. To stress the transparency of the outer skin, the internal platforms and stairs were executed in solid laminated timber, thereby forming independent spatial entities within the overall tower space. The timber members were treated with linseed oil as the sole form of protection.

   For article with details (plan/sections) go to the DETAIL website

2. on 23 Apr 2009 Lusas

   The wooden observation tower at Helsinki Zoo in Finland was the winning design in a competition held for architectural students of Helsinki University of Technology. Situated on a small island just outside the city, and built on one of its highest hills, it provides visitors to the zoo with panoramic views over the sea and surrounding area. LUSAS Civil & Structural was used in the design and analysis to prove the safety and structural behaviour under imposed loading.

   Overview

   The tower is a 10m high, two storey, irregular-shaped wooden lattice structure built from 72, twelve metre long, glue-laminated battens. The battens were factory bent to 7 different preformed shapes ready for assembly but to achieve the final shape they had to be bent and twisted further during the construction process. The wooden members are connected with double-sided nail plates and 10 mm through-bolts to form a space truss. In all, there are more than 600 joints in the tower. Two floor levels are supported by edge beams at the perimeter and connected to the truss by deck bolts to give the necessary horizontal stiffness and support to the lattice members. A steel framed opening in the shell provides access to wooden stairs. The whole structure rests on a hidden reinforced concrete foundation via specially designed steel joints.

   For more on modelling and analysis check out the Lusas website

3. on 23 Apr 2009 LT

   The load bearing structure consists of 72 long battens, with a section of 60mmx60mm, that are bent and twisted on the site from seven pre-bent types. Over 600 bolted joints hold the shell structure together.
   Having no weather protection the wood is treated with a linen oil-based wood balm with UV-protection.