DESIGN OF BURIED CONCRETE BOX STRUCTURES
Click on the Clause No. for the commentary.
Loads due to temperature.
What are the maximum and minimum effective temperatures for cover depths between 0.2m and 0.6m as they are not included in BD 37?
BD 31 makes no distinction for temperatures on structures with cover depths between 0.2m and 0.6m. BD 91 clauses 3.3.4 to 3.3.6 make allowances for different fill depths over the structure which resolves the anomoly in BD 31.
Background information to the development of the National Annex to BS EN 1991-1-5: 2003 says that there is very limited research on the temperature in buried structures, and no evidence to justify the difference in approach to the treatment of thermal actions in BD31/01 and BD91/04.
Both Standards were reviewed in drafting the NA and the approach given in BD91/04 was adopted as there was little physical justification for the way BD31/01 treated temperature differences.
It would therefore be reasonable to adopt the BD 91 solution if the values obtained from BD 31 were too onerous.
Last Updated : 20/01/2013
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