Enlarge existing footing??

[BSE05]

Has anyone enlarged an existing concrete spread footing by doweling reinforcing into the sides and pouring a larger footing around the 4 edges of the existing? (adding floors to existing building)

Not my idea, I would like to remove the existing and build a new footing. The builder suggested this to save shoring costs and minimize disruption to on-going operation at the footing level.

The Owner of course thought this was a wonderful idea!

I'm cross posting to structural also.

 

[Qshake]

I've done this with major bridge footings that would impact traffic if we had to remove them and the supporting columns/beams.

Building footings seem smaller and more redundant such that doweling is too labor intensive (read time consuming) and expensive.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[dik]

yes, but also by providing a 6" or 8" bit of the footing underneath the existing footing, dowelling it using Hilti Hit and using 'wrap around' rebar in the square 'annular' ring.

Dik

 

[Ingy]

Caltrans (California DOT) does this quite often on its bridge seismic retrofits. Usually the extra footing area is required to tie into the new piles or CIDH's needed. Their detail is usually 6" - 8" split around the sides. A splitter is used. Dowel down with a rock drill (1" dia) at 6" o.c. then use a hydraulic splitter to break away. Then use a demo hammer to get rid of the rest. They dowel in rebar at a 3:1 slope and use Set45 grout. Then, rebar all around. They may have some information in their seismic design manual

http://caltrans-opac.ca.gov/publicat.htm