Quote:
Originally Posted by amaddry
Old barns do not fail because of creep - they fail for the same reason mentioned above - maintenance.
When barns fall into disuse the roof is not maintained and then water gets into the building and gradually destroys the wooden structure. Barns that have proper and continued protection from the elements last for hundreds of years.
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I agree that maintenance and repair is a key component for any structure's longevity, but no amount of maintenance can undo creep strain. Even if the participating load were to be removed, there is some possibility that the creep occurred in the inelastic range (meaning that it never be erased).
There are many types of failure - strength being only one. Failure is also achieved if serviceability is lost, stability is compromised, or excessive fatigue is accumulated. Sagging beams are a result of only one thing - long term creep. Slanting walls and leaning columns could also be the result of ongoing creep strain accumulation. If these conditions persist in any way, the structure may become unusable, unstable, or too weak.
Creep considerations are more common in today's engineering practice but was less likely to be made say 100 years ago. Unaccounted creep would almost certainly reduce any calculated factor of safety - opening the door to a variety of possible failure modes.