CMU Cracks Structurally a Concern?
CMU Cracks Structurally a Concern?
(OP)
The quick question: when do cracks in a cmu wall become a structural concern? Most posts I viewed deal with the cause of the cracks. Once that cause has been determined and fixed than when is the building structurally in jeopardy? I'm not thinking about minor shrinkage cracks but larger cracks. How can I tell if the cracks can be just patched over and when they need some structural strengthening? I've seen this Sikadur 33 but I'm unsure how it will provide structural strength - any experience?
Story: two story cmu building that has raised in one corner of the building due to chemicals that are freezing and expanding in the soils. The building has elevated up to 5" in one corner thus twisting the entire building and leaving cracks everywhere. The solution is to install helical piers to support the foundation and thus cmu building and than remove 6 inches of soil below the footings to allow the soils to continue to expand. (they don't think they can get rid of the bad chemicals in the soil).
Thanks
Story: two story cmu building that has raised in one corner of the building due to chemicals that are freezing and expanding in the soils. The building has elevated up to 5" in one corner thus twisting the entire building and leaving cracks everywhere. The solution is to install helical piers to support the foundation and thus cmu building and than remove 6 inches of soil below the footings to allow the soils to continue to expand. (they don't think they can get rid of the bad chemicals in the soil).
Thanks






RE: CMU Cracks Structurally a Concern?
If you have large X-cracks your wall shear may be been used up. Research some of your FEMA publications (FEMA 310, FEMA 351) for evaluations of existing structures. I believe those have provisions for allowable crack widths.
If you can fit the end of a dime in the crack, it's getting too large. Possibly you can jusify your masonry wall for shear by relying on the reinforcing only. Is there high seismic demand?
RE: CMU Cracks Structurally a Concern?
RE: CMU Cracks Structurally a Concern?
RE: CMU Cracks Structurally a Concern?
If this type of analysis is not practical or reliable then some conservative assumptions are needed which basically amounts to neglecting some or all contribution to resistance in suspect construction and specifying a repair/retrofit or partial/total replacement to make up the difference.
RE: CMU Cracks Structurally a Concern?
What makes them think that the pile would not also be subject to frictional uplift from the expanding soil? I assume the Geotech considered this...
Mike McCann
MMC Engineering
RE: CMU Cracks Structurally a Concern?
haynewp: I just joined this project and I think it was the geotech, I still can't get past the fact they don't care about solving the actual problem. Drives me nuts to not have a solution to a problem. Instead just a fix.
Thanks for the input: I purchased Day's book and we'll be strengthening the short walls since their capacity is more critical.
Tony