Design Uncertainty

This short report considers some key questions surrounding uncertainty in the design process. The present-day influence on structural design of two key figures in probability theory (Thomas Bayes and Ronald Fisher) is considered in the context of the Eurocodes. The report offers potential starting points from which actions taken in the design process might be critiqued with a view to improve design and reduce inefficiency in the use of structural materials. The report has been written as part of the wider project “Minimising Energy in Construction (MEICON)” ( which has a long term vision for the built environment to be designed cost-effectively, based on whole life cycle energy consumption using minimum material resource for appropriate performance.

Throughout the report, questions raised in the first MEICON report “Survey of structural engineering practice” ( are highlighted when appropriate. These “Industry Questions (IQ)” and “Research Questions (RQ)” remain open for all readers to help the MEICON team to answer.


Recommended reading

The following are recommended to give some additional background:

  • Silver, N., 2012. The signal and the noise. The art and science of prediction. London: Penguin Books.

  • Beal, A., 2011. A history of the safety factors. The Structural Engineer, vol. 89 (20).

  • Bolton, M., 1993. What are partial factors for? International Symposium on Limit State Design in Geotechnical Engineering, Copenhagen, pp.565-583

  • Bayes, T., 1763. An essay towards solving a problem in the doctrine of chances. Philosophical Transactions of the Royal Society, vol 53.

  • Melchers, R., 2018 Structural reliability and analysis, 3rd Edition. Australia: John Wiley.