The first glulam structure is considered to be the auditorium of King Edward’s College inSouthampton from 1860 roku. In 1906 Otto Hetzer obtained a DRP patent no. 197773 for glued, bent, layered beams composed of two or more lamellae, which remain inseparable even in the presence of moisture.
Thanks to Hetzer’s method it was possible to go beyond the natural length and girth of individual elements. Even wood species considered weaker from a statical point of view could be converted into large-span structures. Otto Hetzer consistently exploited these advantages. His structures’ dimensions were adjusted to the static requirements of particular wood types and their height almost always corresponded to these requirements while maintaining fixed beam cross-sections. At that time double-T cross-sections were used.
Hetzer’s method invented in the beginning of the 20th century revolutionized and started a new era in wood construction. It was now possible to produce wooden structures with a span of up to 40 m.
For a long time there was no solid and at the same time rigid joining substance appropriate fo use in wood construction. Hetzer solved this problem in the following way: he glued several individual pieces, which allowed to prevent thin-walled wood from twisting and breaking. He also developed a glue which was stronger than wood itself.
Important BSH structures
- German railway hall built for the 1910 World Exhibition in Brussels;
- Elefantenhaus - Cologne;
- the bridge over the river Main and Danube near Essing;
- a pool in Ensched;
- a symulator of Earth’s magnetic field;
- a marina near Rendsburga;
- the roof of an exhibition pavillion for the Expo fair in Hannover.
Hüttemann’s BSH structures
In the second half of the 20th century, Hetzer’s technology was developed towards the modern BSH, which is usually produced from European spruce. The boards are technically dried in large drying furnaces for 3 to 4 days, in a temperature of approximately 70 degrees Celcius. Due to the fact that the average humidity level in buildings is at approx. 11%, the boards are dried up to this level in order to avoid significant humidity changes, thus preventing the components from shrinking or expanding.
Modern BSH, a technically advanced product, has proved to be a particularly useful building material for erecting large-span halls (over 100 m). BSH has been used to create different complex shapes, e.g. in the construction of a salt-water pool in Bad Dürrheim or the Elefantenhaus in Cologne. This material also allows to build support-free roofing for large sports facilities, such as in the case of the SAP-Arena in Mannheim (dimensions: 60m x 120m). BSH is also used for the construction of many bridges, among which the 200 m long suspension bridge for pedestrians with a maximum span of 73 m is a good example.
Glulam construction technology goes even further. New, exceptionally strong joining elements were developed for combining particularly large load-bearing components. These elements are made of steel or very hard synthetic materials and can be glued, which allows to greatly increase BSH components’ load-bearing capacity. Fully automatic machines for treating and assembling construction components execute all cuts and trims with previously unattainable precision. These improvements allow to further expand the use of BSH as a high-tech product with almost unlimited possibilities.