What order of magnitude would common strains take on within concrete bridges? I am looking for types of strains that develop over longer periods of time as well as strains due to dynamic loading.

Wikipedia states the following on their page on concrete creep and shrinkage:

Changes of pore water content due to drying or wetting processes cause significant volume changes of concrete in load-free specimens. They are called the shrinkage (typically causing strains between 0.0002 and 0.0005, and in low strength concretes even 0.0012) or swelling (< 0.00005 in normal concretes, < 0.00020 in high strength concretes).

I suppose this is a type of strain that develops over longer periods of time. How about strains due to earthquakes?


1 Answer 1


The answer should depend on what strains are you interested in. For longitudinal strains, 0.001 (that is, 1 mm/m) is a usual figure to predimension joints in bridges, and that is quite independent from loading, since most of strain comes from shrinkage and thermal deformation - as the Wikipedia article you quoted says.

If you are interested in strains caused by actions, you should look at the most bended sections and how are they dimensioned. Bended sections are dimensioned with two limit states in mind - sometimes explicit, sometimes implicit, depending on the method used:

  • Maximum strain in concrete about 0.0035 in compression.
  • Maximum strain in rebar steel near the elastic limit - that is, about 0.002 depending on steel grade.

If the bridge is properly dimensioned, those strains shouldn't be exceeded even under dynamic loads if the bridge is expected to remain undamaged.


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