By Jacob Bugge
Writer, engineer, MSc, Veddinge
Buildings erected today will have to withstand the environmental actions of the future, not those of the past.
A number of meteorologists anticipate weather pattern changes that will lead to higher loads on buildings; some believe that we have only seen the beginning of this. Such changes may be caused by the global warming according to the IPCC, which incidentally is not the subject of this contribution.
Therefore I have addressed ISO, CEN, and DS, suggesting their changing the load basis of the standards so it is based upon the most unfavourable supportable assumptions and projections.
This includes snow loads, wind actions, actions from waves, currents, and ice, effects of changes in sea and groundwater levels, and flooding as a consequence of wind, precipitation, and melting of snow.
The change would be a proactive approach which may uphold the hitherto level of safety. Relying on distributions covering past years would be a retroactive approach which may lead to diminishing safety.
A proactive approach may lead to unnecessary, exaggerated, erroneous, or even detrimental, precautions; on the other hand, a retroactive approach may lead to lack of adequate and timely action. Obviously, both may be aggravated if any of the parties in the case may derive an advantage from supplying incorrect or inaccurate information.
In connexion with standards, the proactive approach may prove to be well on the safe side, but that would only lead to unnecessarily strong buildings, and the extra costs would be limited as compared to the overall building costs.
Conversely, the retroactive approach may prove to be on the unsafe side and lead to loss of life and property, maybe unacceptable losses; it could also threaten the entire insurance business, thus removing the general securing of property.
The basis of the standards in distributions covering many years may therefore be a weakness rather than a strength.
Similar considerations should apply to other areas.