Rebar in mass concrete
Rebar in mass concrete
(OP)
How much rebar is needed in 15'x15'x10' deep mass concrete footing. It is carrying a 125' high chimney stack on top. Do I only need minimum temp & shrinkage rebar mats located at top & bottom of 10' deep footing, or need more rebar mats thru out fooring depth? ACI does not seem to indicate rebar requiremnents for "mass" concrete?






RE: Rebar in mass concrete
RE: Rebar in mass concrete
While we did everything we could to specify temperature control in the mass concrete, including monitoring instrumentation, we decided to approach the stress/rebar problem with a sledgehammer instead of a more precise design.
Essentially, we looked at a combination of flexural behavior (yes, I know its a big mass of concrete that doesn't really behave in flexure) as well as some shear calculations to ensure that the individual piers (6 of them) wouldn't create a shear friction issue - see ACI 15.5.
We ended up with a top and bottom mat of steel and a middle level mat. All of which were tied together with vertical stirrups which followed the path of interior "beams" within the mat spanning from pier to pier.
Short of the above, the only other concept would be to model the mat with 3D finite elements. Even then, you would get your stresses but it would be difficult to model the thermal stresses which might develop within the mass.
RE: Rebar in mass concrete
I dont see why any reinforcement will be needed apart from some surface rebars if it is a gravity type of a structure.