Changes to Standards on Imposed Loads for Buildings

O2 emissions Professor Arthur Bolton has written from Edinburgh: We hear a lot about greenhouse gases nowadays, especially from commentators who understand little about it. A recent TV presentation showed dramatic pictures of buildings on the east coast falling down cliffs into the sea and pictures of 20ft waves breaking over sea walls. The commentator’s point was that it was all due to global warming, with the ‘proof’ being that the sea level had risen 5mm during the last 50 years. Engineers know that a depression over the North Sea can cause a surge of value many dozens of times this figure - so what is the real situation?

Sulfate attack of concrete has long been recognised and is minimised in the UK by following best practice guidance. Since 1990, however, a few cases of a new form of attack - the thaumasite form of sulfate attack (TSA) - have been discovered in buried concrete. Deterioration of the concrete foundations to three domestic properties in the Cotswolds area was reported by the Building Research Establishment (BRE). During 1998, TSA was discovered in the foundations of a number of 30-year old bridges on the M5 in Gloucestershire. The Thaumasite Expert Group

It is proposed that the provision of adequate safety in structures depends on the satisfaction of three independent requirements: adequate safety factors, adequate control of the design and construction process, and adequate robustness. Only the first of these is currently susceptible to quantitative treatment. A proposal for the more rigorous, quantitative treatment of robustness is developed. It is suggested that most failures result from errors and that the risks to health and safety from failures result largely from insuficient robustness. The risks from failure may not be greatly changed by changes in safety factor. Professor A.W. Beeby