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Reinforcement of massive pedestals

[Subject Prev][Subject Next][Thread Prev][Thread Next] I need to design a footing for a large vertical vessel in a highly seismically-active area. Soils are good, though, and allow the footing pad to be 20'x20'x36." The loads (including considerable weight and seismic shear and uplift/pullout) are applied through three baseplates @120 degrees connected to a 12'x12'x4'-6" pedestal centered on the footing. The pedestal height is dictated by the technological process.

Within the contact areas I installed rebar cages similarly to short tied "columns." I also tied the tops of the three "columns" together with rebars to resist considerable shear.

Unsure about the reinforcement of the rest of the pedestal. Both the ACI 0.0018 and Caltrance's 0.0025 reinforcement ratios appear to be excessive.

Any thoughts about how to reinforce the pedestal away from the areas of contact (apparenly, minimum reinforcement)?

Steve Gordin, S.E.
Irvine CA

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