Glued laminated timber space truss systems
Summary, in English
and use minimum materials to maximum structural advantage. To quote Makowski,
"Natural forms act in the direction of minimum effort". Man has not been slow in copying
these examples drawn from Nature. The main structural aim which drives the use of this construction system is to use the least material possible to achieve a lightweight structure and at the same time have good characteristics of rigidity and restricted deformation. The proposed construction technology can provide ample opportunity for structural engineering; it lends itself to the creation both of bridges of considerable importance and of three-dimensional structures for covering large areas without the use of bracing elements.
Nowadays, the development and diffusion of timber construction systems demonstrate
their validity and competitiveness especially in the construction of roofs and bridges, even with long spans. This has given rise to the idea to use timber even for the space frame technology. The research will be directed to explore the possible applications of the system, initially scheduled for tubular steel structures, in the field of wooden construction. Always used as a structural material in the construction of frames, floors, roofs and bridges, timber material has found high regard in modern civil constructions. In the building industry we often talk about sustainability, energy conservation and the need to relate the constructions with the hosting environment, from this perspective timber has been greatly revalued rediscovering the qualities well-known in traditional building regarding the excellent mechanical characteristics, the simplicity and the versatility for esthetic and modern architectural use. The idea of applying this technology to laminated wood structures was proposed by ing. Arne Emilsson of the engineering company LIMTRÄTEKNIK AB which boasts
a long career in the design of timber structures in Sweden and always looks for new applications of the material in modern buildings. The proposed research project is inserted
harmonically in a larger context that sees the Università degli studi di Trento and the Lunds Tekniska Högskola busy with their own research institutes and associated companies in the development, use and promotion of wood as a building material. The research is directed to explore the possible applications of the space frames system in the field of wooden construction, the proposed construction technology can provide ample opportunity even for timber engineering. The aim of the thesis is to prove the possible application of the timber material considering that the design of wood structures is very complex and requires detailed theoretical knowledge accompanied by the intuition and the ability which comes from an understanding of the critical points of the structures. The work is organized into several parts that try to consider all the thematic relating to the design of the specific construction technology and the material particularities.
Part I describes in general the timber space frames system; it elencates the description,
the development, the components and the advantages of the technology. It also
introduces and correlates the use of timber material in the space frames system listing
any possible issue related.
Part II is about the development of the connection system for transferring the axial
stresses from the member to the node. The connections must be able to resist cyclic
stresses, exhibiting a good ductile behavior, allowing, among other things, to increase
the general robustness of the construction. Different technologies like screws inclined
45° to the grain and pre-stressed bolts working in shear are mentioned for an advantageous
application in the truss system.
Part III treats a specific case study of a space frame court mentioned in the book
«Analysis, design and construction of Steel space frames» (G. S. Ramaswamy et al. 2002)
 . The design of the same construction in glued laminated timber instead of high
resistance steel, using the same geometry and loads demostrates the complete applicability
of the topics treated in the previous parts. The design is performed according to
the new regulations checking the resistance of any element at the ultimate limit state.
The deformation of the connection with preloades bolts and the deflection of the court
are checked to be within the limits recommended.
- Technology and Engineering
- Roberto Crocetti
- Maurizio Piazza (Prof.)
- ISSN: 0349-4969