Ron
Structural
- Sep 24, 1999
- 16,336
Have an issue with a heavily loaded mat foundation and the silos supported by it. About 1 year after construction of the silos (4 silos in cloverleaf group on 1 mat...each silo about 40 feet in diameter by 180+/- feet tall)"caking" problem developed with cement near top of silo (upper 50 feet). Problem obviously from water intrusion, so inspection of silo done and cracks found. Mostly vertical to steep diagonal, with at least one circumferential horizontal crack. Cracks are tight (0.006 inches,max).
Silo Design engineer says cracks are from differential settlement. I disagree and say cracks are shrinkage, since no evidence of any significant settlement(max measured at construction of 1/4-inch), and no evidence of differential settlement. Concrete at crack level is 10 or 12 inches thick and was slip-formed. Mat foundation is 8 feet thick and extends only about 5 feet beyond the silo walls in size. I contend this is too small for any significant bending to occur in the mat, particularly reverse bending as is claimed by the designer.
Does anyone have experience with cracks in cement silos and have any comments relevant to the claimed bending/differential settlement?
Posting this in ACI and Structural also.
Silo Design engineer says cracks are from differential settlement. I disagree and say cracks are shrinkage, since no evidence of any significant settlement(max measured at construction of 1/4-inch), and no evidence of differential settlement. Concrete at crack level is 10 or 12 inches thick and was slip-formed. Mat foundation is 8 feet thick and extends only about 5 feet beyond the silo walls in size. I contend this is too small for any significant bending to occur in the mat, particularly reverse bending as is claimed by the designer.
Does anyone have experience with cracks in cement silos and have any comments relevant to the claimed bending/differential settlement?
Posting this in ACI and Structural also.
