Glulam

Timber is an ambiguous material, saturated with implicit values of sustainability, and locality, and at the same time globally ubiquitous. This essay examines the curious moment in Norwegian architectural history when timber, long associated with tradition and craft, became an industrial material of mass-production—in particular, through prefabricated structures produced by the Norwegian company Moelven Brug. By tracing the marketing narratives behind the company’s two main products—large timber housing panels and glued laminated (glulam) beams—this essay reconstructs a complex field of ideas related to building with timber. It argues that, on one hand, Moelven products reflected shifting architectural attitudes towards timber in mid-twentieth century Norway, treating it as the most “neutral” material, and on the other, they shaped new narratives of “updated tradition” advanced through the use of engineered timber in representative buildings. A curious by-product of a marketing narrative, the myth of updated tradition survives until today, providing a local resolution to the homogeneous global typologies of timber construction.

Glulam construction arrived Switzerland a few years after Hetzer’s technological invention of robust industrially fabricated glued timber elements in Germany. In 1906 the Swiss engineers Terner and Chopard acquired the patent and the exclusive rights and during the following 24 years developed many timber structures which have been acknowledged internationally as belonging to the most distinguished architectural examples of timber construction of that time. Among their most notable projects are two exceptional timber domes, built almost simultaneously, but using different constructional approaches. The bell-shaped dome of the new university main building in Zurich (1914) has a series of delicate rafters integrating the structure and form of the roof, while the dome of the new SUVA head quarter in Lucerne uses a hierarchical structure with massive timber girders and additional rafters to provide the dome shape.
This paper examines the development of both domes in the context of early glulam technology in Switzerland. The two structures are the finest examples of the first peak of Swiss timber engineering. The wide application of glulam timber construction helped to accumulate extensive technological knowledge both in timber engineering with Terner & Chopard and building construction with the few licensed contractors. The two domes can thus be considered a prelude of the high profile timber engineering focus in Switzerland.

Early glue laminated timber in Switzerland was used for many functions: industrial but also regular buildings such as sport halls, cultural buildings and housing. Integration of the new practice was only achieved by involving existing traditional players. Contractors had to bring together a long-standing knowledge of local timber craftsmanship and the patented glulam technology. The paper traces the early onsite construction practice of glulam by looking at the handling of the contractor for both fields, the use of glulam for industrial oneroom structures and for the use of large glulam elements in roofs of ordinary buildings. The licensed contractors developed methods for fast and flexible erection of the glulam parts. Key was the development of a constructional unit, the two girder halves with post and tie beams, that was fully joined flat on the ground and then, as an entity, lifted into place, using tripods or other movable lifting devices.

Geniş açıklıklı yapı ihtiyacına yönelik tasarım anlayışının, 20. yy’ın başlarından itibaren  kendini gösterdiği söylenebilir. Bu anlayışta, malzeme, biçim ve taşıyıcı sistem bir bütün halinde değerlendirilir ve tasarıma katılır. 20.yy’ın ikinci yarısından itibaren gelişen lamine ahşap kompozit eleman (glulam) üretim teknolojileri, geniş açıklıklı ahşap yapı tasarımını mümkün kılmıştır. Bu çalışmada çubuk ağı kabuk sistemler genelinde; önemli bir uygulama alanı bulan tek tabakalı ahşap kubbeler incelenmektedir. Malzeme, form ve taşıyıcı sistemin verimliliği, bilinen en geniş açıklıklı ahşap kubbe örnekleri üzerinden karşılaştırmalı olarak irdelenmektedir. Kubbe maliyetine etki eden parametrelerden biri taşıyıcı sistemin tipi ve basıklığıdır, jeodezik sistem ekonomikliği ile tercih edilmektedir. Birleşimlerin teşkil biçimi ve yükleri taşıma kapasitesinin yanısıra; kubbe yüklerinin zemine aktarılma biçimi de önemlidir. İncelenen örneklerden, yüklerin payandadan çekme çemberine aktarım biçiminin en uygun çözüm olduğu görülmektedir.
It can be said that the concept of design for the needs of the wide-span structure has emerged from the beginning of the 20th century. In this approach, the material, form and structural system are evaluated as a whole and are included in the design. Since the second half of the 20th century, the production of glue-laminated members (glulam) has made possible to design wide-span wooden structures. In this study, single-layer reticulated wooden domes which have an important position in the application area are addressed. The efficiency of the material, form, and structural system is investigated on the well-known largest-span timber domes. One of the parameters affecting the cost of the dome is the type and aspect ratio of the structural system, geodesic system is economically preferred. In addition to the load-carrying capacity of nodes and connections, transferring of the loads on domes to the ground is also important. The load transfer from buttresses to the tension ring seems the most appropriate solution.