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TIMBER FRAME BUILDING SYSTEMS

Objective

1.General background

There is a great need in many countries to increase productivity and competition in the building sector. One way to achieve this could be to develop and strengthen the position of light-weight timber frame building systems on the market. Experience from North America and some European countries indicate that it is possible to reduce the cost of low to medium rise (2-7 storeys) buildings significantly by using light-weight building systems based on timber and panel products. These systems have the advantage of simple construction techniques at the building site and very short construction times can be achieved. Among other advantages, it should be noted that timber is an environmentally friendly, easily recyclable material, useful in that it stores carbon dioxide, which will be increasingly important for future competitiveness. An increased use of timber in the building sector will also lead to a more efficient use of European forest resources and stimulate the economy in the forest sector, a matter of great importance for rural areas.

Whereas timber frame building systems have a dominating position in North America, the situation in Europe as a whole is quite the opposite. Due to prescriptive fire regulations and strong building traditions, concrete, steel and brick are historically the major structural materials for residential housing in Europe. There is, however, a long experience with timber frame buildings for low rise buildings (mainly single residential houses) in the Scandinavian countries, UK and to some extent in other European countries such as Germany, Austria and Switzerland. New performance based fire regulations are now being introduced in many countries, a development which has been stimulated by the European harmonization of codes and standards. This makes it possible to use timber as a structural material also for multi-residential, medium-rise buildings. There is a clear potential to develop timber frame building systems as a cost-effective alternative to other types of building systems, which would increase competition on the European building markets to the benefit of consumers.

Differences in buildings traditions, market requirements and other boundary conditions makes it impossible to copy technology, construction methods and design from North America into the European markets. As with any new and largely untried form of construction, there are technical issues which need to be resolved. These relate to methods of design, construction and performance, which are currently addressed on a rather ad hoc basis, with no real mechanism in place to ensure consistency of approach. There is widespread concern amongst the industry and regulatory authorities that methods do not exist to demonstrate common rules for safety and performance, which, if left unresolved, will prevent significant growth of this market. Therefore, significant R&D efforts are needed to solve various strategic problems associated with light-weight building technology, especially for medium-rise buildings.

Such R&D activities, dealing with e.g. stability, fire, acoustics, serviceability requirements, heat insulation and construction methods, are undertaken in a number of countries in Europe at the moment, with close collaboration between industry, research institutes and universities. As an example, an internordic research programme, involving six experimental housing projects and a number of research projects in four different countries, has recently been started. In the UK, a feasibility study has been carried out on five-storey buildings already constructed. A proposal has been approved to construct a five-storey building for testing in the Cardington laboratory of Building Research Establishment.

2.Objectives

The purpose of this COST action is to facilitate efficient cooperation in the conduct of research and in the exchange of information between interested parties in the European countries concerning timber building systems. The emphasis is placed on systems, i.e. from the researchers' point of view the activities are to a great extent interdisciplinary. The target group for the activities should be professionals from research institutions as well as from relevant industries, such as building companies, designers and manufacturers of timber components as well as timber suppliers. The expected benefits from the COST Action are:

.More effective sharing of research results

.Transfer of knowledge between European research institutions

.Transfer of knowledge between research and practice

.Initiation of collaborative research programmes on a European basis

.Initiation and support of interdisciplinary research activities

.Development of new market outlets and added value for European timber resources

.Stimulation of joint ventures on a commercial basis between European companies in the building sector and in the timber producing sector.

3.Programme of the Action

Type of activities

Tentatively, the following activities may be considered to achieve the objectives:

.organization of workshops, conferences, seminars, site visits etc.

.exchange of researchers and specialists

.exchange of publications and documentation

.state of art reports, workshop proceedings and practical guidelines may be jointly published under the umbrella of the COST Action

.joint projects in specific areas may be launched by two or more of the participants in the action.

Scientific areas

The scientific field to be covered by the action should be directly related to the development of timber frame housing systems. The relevant research issues are grouped into the following main areas:

.safety and structural stability

.serviceability of elements and systems

.interdisciplinary system aspects.

Safety and structural stability

In general, research aimed at a better control of engineering properties of timber materials, elements and systems. Due to its natural variability, the reliability of structural timber is often questioned and since wood is a combustible material the fire safety of structural timber elements and systems has to be demonstrated in a convincing way.

Specifically, priority is given to research dealing with

.re-evaluation of fire safety principles for whole buildings employing modern methods of risk analysis

.structural fire resistances of building components containing wood

.disproportionate collapse

.stabilization of timber framed buildings against actions of wind and earthquake

.wind shielding factors of masonry cladding.

Serviceability of elements and systems

Research concerning serviceability aspects of light-weight timber frame building systems, such as sound and vibration performance, as well as dimensional stability under action of moisture variations and external loads. For lightweight structures it is difficult to ensure a good sound insulation, particularly in respect of impact sound on "floating floors". Shrinkage and swelling of wood due to variations in moisture have to be mastered to ensure dimensional stability in structural components and in building systems during construction and use.

Specifically, priority is given to research dealing with

.acoustical properties of light-weight timber floor and wall elements

.control of floor vibrations

.behaviour of wood-based components under environmental variations

.shrinkage and compression under concentrated loads perpendicular to grain.

Interdisciplinary system aspects

A significant part of the activities will be devoted to optimization of the integrated performance taking into account all relevant technical requirements on components and systems. In this context the following aspects of the building system will also be addressed

.efficiency of different construction methods on site involving various degrees of prefabrication

.performance and design of composite structural elements, e.g. concrete and timber in combination

.construction costs and other economic aspects

.design of the building envelope, which should provide thermal insulation, prevent air leakage and damage from internal and external moisture exposure.

Important elements in dealing with system aspects are the experiences gained from a number of construction projects which are under way in various countries in Europe. Activities will be arranged to communicate such experiences among the participants in the programme, as far as competition between companies allows such communication.

4.Time-table

The duration of the action is 5 years. The contacts among researchers generated by the action is expected to lead to exchange of researchers between laboratories. The total number of exchanges can be estimated to about ten during the five year period. Most of these are expected to be of short duration, i.e. maximum 2 weeks.

5.Organization management and responsibilities

The Action will be lead by a management committee (MC), which will simultaneously have the role of a technical and research committee. The MC is responsible for all decisions about activities and initiation of them. Responsibility for detailed planning, execution and documentation of each individual activity is delegated by the MC to a task force, which normally may be established within one country for one specific task. The task force is lead by a person appointed by the MC. The responsibility of the task force ceases when the activity is completed.

The activities within the COST action is related to several research programmes and other activities known to be pursued during the time span of the Action. In Scandinavia a cooperative research programme is running from 1995 to 1997 with a possible extension beyond 1997. In the UK a five-storey timber frame building will be built for testing at the BRE full scale test facility in Cardington. Researchers will be invited from other European countries to participate and/or design their own test programmes in this project. A Eureka initiative dealing with related problem areas has recently been initiated by Austria. It is expected that people responsible for these programmes will take active part in the Action.

6.Economic dimension of the Action

The turnover of the research and development subject to coordination and cooperation within the Action is estimated at 9 MECU per year.

Current status

COST Action E5 met for the first time on 29 Feb 1996. The first activity was a workshop on Timber Frame Housing in Europe - Current Status and Development, for defining state of the art and research needs. More than 50 experts participated. The programme included visits to three housing projects in 3-4 storey timber frame. The proceedings will contain written papers from all presentations, as well as discussion summaries.

An ad hoc working group with the task of further defining the research needs and suggesting priorities has been appointed under the chairmanship of Prof. Alpo Ranta-Maunus from VTT in Finland. The next major event will be a workshop in Finland in June 1997 on Fire safety in timber frame buildings. An ad hoc working group is planning this workshop and is also charged with producing a report documenting current fire regulations in the European countries and as well as methods for verification of fire safety in timber frame buildings. This report will serve as a basis for national reassessments and (hopefully) harmonisation of fire safety requirements in Europe. Current requirements very widely, much more than can be explained by cultural differences. Modern risk management approaches must be applied, as strong evidence indicate that current requirements are not the result of rational analyses of fire risks.

A major conference will be organised in the UK in 1998, in connection with the national research project Timber Frame 2000, which includes full-scale testing of a 6-storey timber frame building in the BRE facility at Cardington.

The Action encourages the exchange of researchers through the Short-Term Scientific Missions programme.

Call for proposal

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Funding Scheme

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Coordinator

CEC
EU contribution
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Address
Rue de la loi 200
1049 Brussels
Belgium

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Total cost
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