Existing Mechanical Tower Foundation not following ACI Seismic Detailing Requirement
Existing Mechanical Tower Foundation not following ACI Seismic Detailing Requirement
(OP)
Hi guys. I reviewed an existing steel frame tower (for a food processing plant) on piled foundation. My initial check goes fine by strength and serviceability, but i was worried that the RC pedestals did not follow appropriate seismic detailing (located at high seismic risk zone). It was like around 500x500mm cantilever pedestal with 8-d20mm main bars just hooped by d10mm ties. My concerns are:
1. Roughly the equally-spaced bars were at 190mm on center spacing, wasn't it supposed to have cross-ties by ACI318 seismic detailing?
2. If such cross-ties were really required for seismic detailing, the trouble was, the pedestal is already existing. Does this conclude to demolition though by strength the pedestal is still good? Or retrofit by any means possible without totally knocking down the pedestal?
1. Roughly the equally-spaced bars were at 190mm on center spacing, wasn't it supposed to have cross-ties by ACI318 seismic detailing?
2. If such cross-ties were really required for seismic detailing, the trouble was, the pedestal is already existing. Does this conclude to demolition though by strength the pedestal is still good? Or retrofit by any means possible without totally knocking down the pedestal?






RE: Existing Mechanical Tower Foundation not following ACI Seismic Detailing Requirement
Dik
RE: Existing Mechanical Tower Foundation not following ACI Seismic Detailing Requirement
RE: Existing Mechanical Tower Foundation not following ACI Seismic Detailing Requirement
if not comfortable with that approach, then do a little research, and if still not comfortable, then recommend that it be reconstructed to conform.
Dik
RE: Existing Mechanical Tower Foundation not following ACI Seismic Detailing Requirement
RE: Existing Mechanical Tower Foundation not following ACI Seismic Detailing Requirement
I don't know much about your system but I would be surprised if your pedestal is actually an element expected to undergo serious inelastic deformation. When that is the case, there's usually a way around adherence to the high ductility requirements.
Another approach, if you truly have a lot of excess capacity, might be to simply disregard the presence of the vertical bars that do not have ties.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Existing Mechanical Tower Foundation not following ACI Seismic Detailing Requirement
Great advice...
Dik
RE: Existing Mechanical Tower Foundation not following ACI Seismic Detailing Requirement