Background and activities


Comfort properties of timber floors constructions


The overall scope of the project is structural parts in buildings like partition walls and floor constructions of typical composite design where wood or wood-based materials are one of the materials used. Emphasis will be put on the vibration response of floor constructions exposed to human activities and common vibration sources in relevant building categories.

A more extensive use of wood in buildings is of strategic interest both from environmental points of view and from the view of the small and medium sized industry. One possibility is to develop products and solutions for extended use in multi storey buildings taking the increasing urbanization into account.
Use of wood in floor constructions with human activities is to a large extent governed by comfort properties and protection against fire. The comfort properties include sound insulation, deflections and vibration properties. Today, span width of such timber floor constructions is limited by deflection and vibration properties, not the load bearing capacity.
In Europe new rules for the design of timber structures, Eurocode 5 (2003), have been worked out. All conflicting standards shall be withdrawn at the latest by March 2010. Although the Eurocode 5 has been based on comprehensive research carried out in various countries, the serviceability criteria for residential floors are very inadequate. Furthermore, Eurocode 5 does not offer any tool or guidance for the development of new partition structures.
To days praxis is to perform testing of every new concept of floors and walls in buildings to find out if they have the desired properties regarding comfort properties for people or equipment as well as for sound insulation. Most floor structures are compounds or composites, and there is much "trial and error" to find good and economical solution to this. Basically, prototypes of new structures are built in full scale and tested, either in the laboratory or on-site.
A more rational and economical way for this search for better floor or wall structures would be to develop the necessary technology and models for numerically to perform the evaluation of new concepts based on fundamental knowledge of the various material involved and their interactions.
 Objectives and approach:
Objectives of the research project are to gain more knowledge and enhanced competence in order to develop better methods for design of partition walls and timber floor constructions with improved vibration properties compared with existing, common solutions. This goal shall be achieved through the development of numerical models of typical partition structures like composite floors, exposed to human activities and common vibration sources. The results from the numerical simulations will be compared to experimental results from critical components and materials as well as measured response on complete structures.
Simulations with finite element models (FEM) in this problem area require quite sophisticated models regarding the transfer of vibrations from one structural component to another. Key properties here are; contact properties of connection surfaces/connections, damping properties of components and between components, and damping properties of connections using mechanical fasteners. In addition adequate loading models have to be used. It will be necessary to verify the numerical models by experimental testing.
The basic approach is to perform research work on numerical FEM models useful for studies of wood composite structures, and experimental work in order to establish necessary material parameters and connector responses.

Scientific, academic and artistic work

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Journal publications