Quick Rebar Size Selection
Quick Rebar Size Selection
(OP)
I am looking for an easy way to figure out rebar sizes for footing pads supporting large columns in an underground parking ramp. The dimensions of the pads have been determined - some are combined and others are individual. This is for a budget price. I need to make sure I have the proper bar size figured in.
There are two conditions
24" x 24" Columns supporting 500 to 2,000 kips.
32" x 32" Columns supporting 4,000 to 5,000 kips.
The net allowable bearing capacity is 15,000 psf
There are two conditions
24" x 24" Columns supporting 500 to 2,000 kips.
32" x 32" Columns supporting 4,000 to 5,000 kips.
The net allowable bearing capacity is 15,000 psf






RE: Quick Rebar Size Selection
For combined footings, check beam and punching shear and determine thickness required. Conservatively use M+ = wL1^2/8 for moment between columns and wL2^2/2 for cantilevered moment. L1 = distance between columns and L2 = largest cantilever. As approx. = Mu/4d. Use continuous top and bottom layers.
RE: Quick Rebar Size Selection
2 minute calculation.
RE: Quick Rebar Size Selection
Maybe you will need to consider something other than an isolated footing.
RE: Quick Rebar Size Selection
RE: Quick Rebar Size Selection
Spread Footings and Mat Foundations are recommended. The maximum net allowable soil pressure of 15 ksf bearing on medium compact to extremely compact fine to coarse sands may be increased by 1/3 for temporary transient loads such as wind and seismic loads.
Deep foundation systems utilizing drilled shafts are possible but difficult to design and construct due to the frequent cobbles and boulders present at the site and the highly variable relative densities of the deep sand and silt deposits. They would have to be constructed with full-length temporary casings to a depth of at least 100-ft.
The use of H-pile or auger cast piles are not considered to be feasible for the project.
RE: Quick Rebar Size Selection
RE: Quick Rebar Size Selection
RE: Quick Rebar Size Selection
RE: Quick Rebar Size Selection
RE: Quick Rebar Size Selection
Thanks for everyone's input.