Bell Tower in Bleibach, Germany
Customer Project
An extraordinary bell tower has been built in Bleibach in the Southern Black Forest Nature Park, Germany. The structure, with a height of approximately 111.5 ft, has a triangular floor plan and consists mainly of cross-laminated timber (CLT).
Investor |
Röm.-kath. Kirchengemeinde Mittleres Elz- und Simonswäldertal Pfarrei St. Georg - Bleibach, Germany www.kath-semes.de |
Architecture |
WerkGruppe1 www.architektur3.de |
Object and Structural Design |
Wirth Haker PartmbB Beratende Ingenieure ing-wh.de |
Construction |
Holzbau Baumer GmbH www.baumer-holzbau.de |
Model Parameters
Model
There is a viewing platform at a height of about 46 ft. Upon request, you can look out over the surrounding valleys and the peaks of the Black Forest mountains.
The engineering office of Wirth Haker PartmbB from Freiburg, Germany, was responsible for the structural analysis of the tower structure. The engineers used RFEM and the RF‑LAMINATE and RF‑DYNAM Pro - Natural Vibrations add-on modules for the structural analysis and design.
Structure
The tower shaft, the bell chamber, and the spire form the three main components of the tower. The ground plan forms an equilateral triangle with side lengths of about 22 ft. The side walls consist of cross-laminated timber elements with a thickness of 7 7/8 inches, made of silver fir. They rest on a reinforced concrete ring foundation with about 11-foot-high foundation walls and an 18-inch-thick floor slab. The walls are anchored in the foundation by means of cast-in steel rod anchors as well as slotted plates and dowels.
You can reach the viewing platform (at a height of approximately 46 ft) by climbing 60 steps and crossing twelve intermediate landings. The level of the viewing platform has a height of about 9 ft. Above this, the belfry extends over two levels (2 x 9.5 ft). The upper end is the spire in the shape of a three-sided pyramid with a height of 36 ft.
The triangular shape of the tower and the wall elements made of CLT with their glued longitudinal and transverse layers ensure high stiffness and dimensional stability of the structure. In addition to the static loads, the dynamic loads due to the swinging bells are absorbed well.
For fire protection, fire resistance class F30 was required. This was used in the fire resistance design of all structural components, including the steps. The vertically arranged facade formwork made of Accoya wood ensures the timber protection of the construction. This wood, chemically modified with acetic anhydride (acetylation), is particularly resistant to wood-destroying fungi and insects as well as weather conditions.
Project Location
Keywords
Tower Lookout tower Cross-laminated timber Timber Timber structures
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Vibration Design of Cross-Laminated Timber Plates
The vibration design of cross‑laminated timber plates often governs for wide-span ceilings.
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