Edge Square Footing

[Lina]

I have designed square tubings (4"x4"x1/4&quot supported by square foundation (4'x4'x20&quot for a retail store adjacennt to other stores. The Owners of the adjacent stores have refused to accomodate in the construction of the square foundation in which haLf the foundation is within their space (edge foundation). Therefore, I have to install the columns that are adjacent to the common wall on the edge of the square footing (4'x4'x20" deep).
My question is, what will be a quick fix to this problem?

Should I increase the foundation and by how much?
Can I run a beam from the edge foundation to an interior foundation to carry over the load?

Thanks for any help in this matter.

 

[Lina]

Using combined footing will not be economical since the spaces available do not lend themeselves to a reasonable rectangular footings (Columns spaced @ 12' o.c.). What about 8"x12" beam connecting edge footing (48"x48"x20&quot to the interior footing (48"x48"x20&quot. The total oad on the edge footing 8 Kips and the total load on the interior footing 22 Kips the columns are spaced @12' o.c.

 

[JAE]

What we have done in situations like this are:

1. Use a cantilevered footing. This is an underground gradebeam that spans from an interior column toward your edge column. A square footing is placed as close to the edge column as possible without extending beyond the property (which is what your client should want anyway - otherwise the adjacent property owners can someday dig into your footing and damage it). The grade beam then spans from the interior column to the edge footing and the end of the gradebeam supports your edge column. The gradebeam transfers the load to the footing without adding an eccentric force.

2. Use a deep foundation system such as drilled piers, augur cast piles, or helical pile anchors. These can be installed just within the property line and be located directly under your edge columns.

 

[ishvaaag]

You have the cantilevered beam (viga centradora) and pulling beam (viga tirante) solutions in one Mathcad sheet of free download at the Mathcad 2000 Collaboratory site.