Cracks caused by earthquake
Cracks caused by earthquake
(OP)
Is it possible that low intensity earthquake can cause only superficial cracks on plasters over concrete? If cracks on concrete appeared after an earthquake, I suppose the structural concrete has been affected thus cracks appeared on plaster. The crack maybe obvious only on the plaster but micro sized cracks may have developed through the structural concrete.






RE: Cracks caused by earthquake
RE: Cracks caused by earthquake
Don Phillips
http://worthingtonengineering.com
RE: Cracks caused by earthquake
RE: Cracks caused by earthquake
If you have a friend who is a structural engineer and can come and take a look, he might be able to assuade your fears, or confirm them.
Mike McCann
McCann Engineering
RE: Cracks caused by earthquake
RE: Cracks caused by earthquake
RE: Cracks caused by earthquake
RE: Cracks caused by earthquake
If we repaired all cracks in concrete structures, all other structural activity would have to cease for us to catch up. Cracks may or may not be cause for concern, and that can really only be determined by structural engineers. You are incorrect in making a blanket statement that "theoretically it is not anymore safe to use".
RE: Cracks caused by earthquake
RE: Cracks caused by earthquake
RE: Cracks caused by earthquake
Mike McCann
McCann Engineering
RE: Cracks caused by earthquake
RE: Cracks caused by earthquake
If you are concerned about cracks, however, you should look in some of the areas you can't see right now. Take down some of the ceiling and look at the underside of the beams or take up the flooring and check out the top of the beams near the columns. Then tkae the time to do that at every one of those beams and repair all of the cracks you find.
RE: Cracks caused by earthquake
True reinforced concrete is intended to "crack" but generally, if they're large enough to visually see and worry about, then they're likely yielding the reinforcement.
Since emanc noted that they're "superficial" and "micro sized" then its really is doubtful theres a problem.
Always know that the intent of the code is to provide a structure that is survivable after an event, not that all elements can be reused. Also to note, the actual force the building sees is about 7x to 10x the code design force.
My guess is the concrete deflected enough to crack the plaster. Emanc, if you dont understand Mcr, then I'd recommend having someone who has a little better understanding of concrete go out and look at your issue.
RE: Cracks caused by earthquake
I agree with your assessment about the steel yielding. I noted this in my first post above (the first post after the OP).
RE: Cracks caused by earthquake
Thanks for further info and suggestion. I will consider that.