Results of the second Workshop on
Wind Disaster Reduction Related to Housing
held in Copenhagen under the Auspices of the IDNDR
An Initiative by the
International Association of Wind Engineering (IAWE)
to reduce or prevent storm hazards to buildings and structures, led to a workshop at the 10th International Conference on Wind Engineering held in Copenhagen in June 1999.
The Steering committee of the workshop consisted of
Alan Garnet Davenport, Canada (chairman)
Hans-Jürgen Niemann, Germany
Prem Krishna, India
other experts that joined the panel were
Tony Gibbs, Barbados
Emii Simiu, USA
The following experts contributed their views
Jacques Gandemer, France
Adam Goliger, South Africa
Michael Knauf, Germany
Financing of this workshop was made possible through the
Deutsches IDNDR-Komitee fuer Katastrophenvorbeugung e. V.
The workshop took place on June the 23rd ; it was attended by about 60 scientists and civil engineers.
The main purpose of the meeting was to bring together individual initiatives, on reducing loss of life and property, into a common worldwide program.
An important phase of efforts to develop storm resistant housing is to establish a central group of experts. Their task is to collect and evaluate data about storm hazards, identify their characteristics and develop strategies for loss reduction or prevention. The presentations of the panelists and experts, and contributions by the audience, provided an overview of the state-of-art.
It is necessary to ascertain commonalties and sitinctions between approaches taken for developing and developed countries. The fundamental issues remain nearly the same.
The level of engineering varies to some extent dedicated by the socio-economic factor. Efforts are going on in various cyclone-affected countries to develop storm resistant housing. In India an expert group has been set up by the government to recommend measures for mitigating hazards induced by Wind, Earthquakes and Floods. Damage surveys following several cyclonic storms have been carried out to record data on typical losses and, on this basis, to develop repair or strengthening methods. It was pointed out, that such an effort can yield significant benefits.
It was also indicated that in the USA most homes are not engineered and can suffer severe damage, including total destruction. Hurricane ,,Andrew" alone damaged severely about 136.000 homes. Also manufactured homes have a disproportionate share of losses in the U.S.
In some cases a trend from aerodynamically favorable shapes to shapes more prone to damage has been noted in the Barbados, where an evolution from hip roofs to gable roof construction has taken place within the last few decades.
Approaches have been discussed to retrofitting houses so that peak values of the wind-load be reduced, to reduction of ram penetration and to optimization of design for tropical climates.
In South Africa in view of the growing demand for suitable shelter, several mass housing developments have been undertaken. Various innovative methods of fast and cheap constructions are being developed and implemented. Unfortunately in many instances inappropriate delivery systems and substandarded construction (which often ignores the wind loading aspects) are used.
Site-supervision is an important component of efforts to reduce losses. It was noted that in the South African Low-Cost-Housing program many of the new homes were not built to standard. This has resulted in massive waste.
A successful method of motivating the home owners to maintain their buildings is to connect premium discounts to certain features of the homes. Manuals developed by insurance companies can help classify buildings and adjust premiums accordingly.
Issues for potential improvements were discussed and are summarised as follows.
- Creation of wind speed maps for different regions of the world to identify the most hazardous areas, and areas where siting and exposure are most unfavorable.
- Education and training of designers, construction workers and house owners has to ensure good design and maintenance.
- Development of a simple code for the design of new construction and for retrofitting the existing housing stock.
- Implementation of on-site supervision must be enforced in the formal and informal sector
- The establishment of Task groups to investigate the causes of housing damage and failures remains an important issues.
- An international design competition would be a mean to promote the development of innovative designs and creative thinking by designers.
The national initiatives in India should be carefully studied worldwide. A study of wind-induced damages depending on the housing type and the climatic zone is an indispensable resource to create simple, but effective guidelines for construction. Similar studies, some of which have been pursued by the U.S. insurance industry, should be conducted worldwide.
An international group of experts should be assembled to coordinate the development of effective solutions. Main areas of concern would be:
1. Development of a worldwide database regarding storm hazards.
2. Identifying damage mechanisms on different types of houses e.g. overturning, shear, uplift, fatigue, wind-borne missile damage, cladding and structural failure.
3. The development of simple compendiums of manuals on procedures to resist wind loads. A so-called ,,ABC code" -anchorage, bracing and connections - is an example such a manual would help to retrofit the existing stock of buildings, and to ensure a high standard for future buildings.
4. A multi-disclipinary approach should be developed, dealing with each climatic situation to reach the final aim:
The construction of a storm resistant ,,core-house" which can be modified by most simple means to fit in each climatic zone of the earth.
The main reason why a worldwide program has not yet started is the absence of financial support for an expert group. Adequate funding is needed to cover the costs of the project including the research outlined above, costs incurred by the IAVVE steering committee, effective liaison with and among entities engaged in wind hazard reduction, research funding, and publications. The work could be carried out in phases, for example, dealing with planning, research and development and applications. Potential funding sources include the World Bank, The Asian Development Bank, insurance and re-insurance agencies, government agencies and the IDNDR.
An advisory committee consisting of
Alan G. Davenport, chairnan
as the steering group, and
T. N. Gupta
will oversee the study.
Bochum, September 21st 1999