Elevation of the footings 1

[Okiryu]

For the structural engineers here, are there any good reasons why you prefer the TOP of the footings at the same elevations? Being a geotechnical engineer and not having any good input from the structural at the first stages of the design, my analysis starts with assuming the BOTTOM of the footings at the same elevations. Any input will be appreciated !

 

[hokie66]

Top of footings don't have to be at the same elevation, but it does make for convenience in construction. With concrete columns, plinths, and walls, the forms start at the same level. For steel columns supported directly on the footings, it make detailing simpler.

The bottom of footings often depends on the soil bearing capacity at the level of intended founding. Also, the footings themselves are commonly of differing thicknesses.

 

[SlideRuleEra]

In poor soil and/or high water table, the bottom of the footing elevation is more important than the top. Don't want to excavate any deeper than necessary and don't want one footing's excavation to be deeper than another that is nearby.

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[Okiryu]

Thanks for your responses.

 

[dik]

makes it a lot easier to form if a wall and all column bottoms are at the same elevation, so detail of granular 'buffer' slab, isolation joint, etc. are all the same...

Dik

 

[Okiryu]

That makes sense. I will talk with local formwork and rebar contractors to also see their opinions. Thanks again !