Wood frame solutions for free space design in urban buildings

WOODSOL develops structural timber solutions suited for industrialization and use in urban buildings. Wooden materials appear to be the only relevant building material giving a positive effect on the climate. A storage for wood is also a storage of carbon dioxide, and wood in buildings makes the buildings into carbon dioxide storages. The production of wooden buildings gives less environmental footprint than using other building materials. The urbanization requests multistory buildings in cities to limit occupied area and transportation. Wooden building systems have been hampered by the legislation of the last century, prohibiting wooden houses in cities. This was recently changed when modern functional based building rules were introduced. Hence, there is a need to modernize the use of wood in city buildings supporting the growing interest for environmental-friendly building materials. The project has developed solutions with framed constructions in wood and moment resisting joints, suitable for urban buildings with 3 to 10 floors. The solutions enable open and flexible architecture with large openings in the walls without tightly spaced columns or load carrying walls. The floor systems consist of wooden composite pre-fabricated decking elements providing competitive features compared to other material systems. The solutions allow easier sectioning into fire compartments, and increased stiffness and mass in the floors provide better comfort properties and sound insulation. The moment resisting frames connecting the floors to the vertical structural elements further improve the floors. The project has documented all relevant properties using experimental investigations and computations. A trial production and mock-up has been built in cooperation with carpenter education at Charlottenlund Videregående Skole, Trondheim. The mock-up was used for characterization of serviceability requirements with respect to acoustics and vibrations as well as quantification of the effects of interconnections between floor elements. The developed floor elements span up to 10 m, having width of 2.4 m in order to be transported horizontally by ordinary trucks. The floor elements allow coupling or no coupling between the elements in the transverse direction. Vibrations and acoustics have been the most important topics and have been thoroughly studied. Results from the mock-up show that a measurement technique based on measured vibrations predicts radiated sound power, and consequently making the use of a traditional sound chambers with low flanking transmission unnecessary. This is verified by tests of the same floor elements at the accredited sound laboratory at SINTEF, Oslo. The results also show a significant positive effect of the use of environmentally friendly gravel infill, which in combination with the usual principles for top flooring, lead to increased sound insulation. The floor elements satisfy all requirements with respect to strength, stiffness, vibrations and acoustics. Furthermore, optimalization procedures for industrial productions of decks have been developed with emphasis on costs and CO2 emission, and these procedures is deemed to be a good foundation for industrial production. For horizontal vibrations, the project has showed that framed systems are well suited for buildings up 8-10 storeys, depending on the horizontal dimensions. In such cases the horizontal bracing can be satisfied using only moment resisting frames. The effect of the moment resisting frames are dependent on a certain stiffness of the columns and beams. In this project it was decided to integrate the beams into the floor elements and in this way the rotational stiffness becomes larger than achievable using only beams. In addition, the floor elements also become stiffer with respect to displacements and vibrations than in other design alternatives. It is also possible to make use of frames in both horizontal directions, but this has not been studied in detail within the project. The critical part in a moment resistant frame is the connection between vertical and horizontal elements. It has been performed series of investigations and experimental tests on alternative lay outs of moment resisting connections. The project has developed a design of a moment resisting connections which are much stiffer than designs known from the literature. The moment resisting connection consists of screwed-in threaded rods combined with coupling parts which enables rapid mounting procedures on building sites. It has been emphasized that all structural couplings should be installed at the production facility, and only erection and mounting should take place at building site. For example, the mounting of a 2.4 x 10 m floor elements will need only two bolts installed into pre-drilled holes in each corner. Parts of the technology developed in the project have obtained many interests and are already taken into use in practical engineering.

Dekke-elementer med inntil 10 meters spennvidde som tilfredsstiller alle krav til styrke, stivhet, nedbøyning, samt vibrasjoner og akustikk er utviklet. Optimalisering av fysiske egenskaper samt pris og CO2 utslipp er et godt utgangspunkt for industriell produksjon. Rammesystemer er egnet opptil 8-10 etasjer avhengig av bygningens horisontale utstrekning. Det kritiske elementet er forbindelsen mellom horisontale og vertikale deler i rammesystemet. En utforming av en momentstiv forbindelse som består av innskrudde gjengestenger og koblingsdetaljer er utviklet. Tre-materialer kan lettere settes i svingninger. Fokus på bruksegenskaper som horisontale vibrasjoner av bygningskroppen, vertikale vibrasjoner av gulv samt akustikk har bidratt til at bransjen har fått større fokus på disse viktige egenskapene og metoder har blitt utviklet og gjort kjent. Ingeniører og arkitekter fått ett nye verktøy i sin redskapskasse, noe som forbedrer mulighetene for fremtidsrettede og miljøvennlige bygg.

The main objective is to develop industrialized structural solutions, based on moment resisting wooden frames, for use in urban buildings having five to ten stories open architecture. A growing potential for use of environmentally friendly building materials in urban buildings is addressed. An open and flexible architecture requires floors without closely spaced columns or walls, which accommodates large openings. A major limitation of wooden systems is the span length of the floors; the four to six meters spans of joisted floors are not suitable. Timber-concrete composite floors have many of the required qualities. The separation into fire compartments becomes easier, both stiffness and mass of the floors will increase, thus improving comfort properties such as vibration and sound insulation. The effectiveness of such a flooring system can be further improved by the introduction of moment resisting connections between floors and columns. These connections may also reduce the need for other horizontal stabilization systems, thus providing a larger degree of architectural freedom by absence of closely spaced columns or walls. The goal of the project is to develop a practical building system with necessary documentation of all relevant properties. The basic ideas and approaches for structural systems and components are the following - Moment resisting frames (MRFs) including prefabricated couplings (MRCs). - Prefabricated timber-concrete composite floors ( TCC) - Assembly and geometric tolerances The most critical challenges are related to structural, safety and comfort properties of the developed structural system, and the following issues will be studied: - Serviceability aspects; stiffness, deformation and vibrations - Safety requirements and performance - Acoustic properties and solutions. Sound insulation of floors, walls and flanking transmission. Effects of MRFs and coupling details - Fire safety concept and rating of the structural system.