grade beam between footing

[ibrahemnasr]

i want to know what is the best position for the grade beam that connect the footings in the case of combined footing? is it from column to column or from the center to center of footings?

 

[a7x1984]

Check the IBC 2012 (if it is a building structure), but I think it should be through the shear center of the line of footings/columns being considered, right?

Before you doing anything creative, make sure the code likes the artwork you are trying to wow the world with.

 

[BAretired]

Your question is not clear. Combined footings do not require a grade beam to connect them as they are already connected. Grade beams are normally provided where required architecturally. Please provide a sketch indicating your situation.

BA

 

[ibrahemnasr]

thanks mr a7x1984
but which clause in IBC speak about position of grade beam?
and what is the shear center of the footing?

 

[ibrahemnasr]

thanks mr BAretired
i mean the case to connect two combined footings or combined footing with isolated one
(i attach a sketch to the case i study)
my question is how can i connect these footings ?
is connecting the footing from two perpendicular directions only sufficient (as i hear)?
is it true to make inclined grade beam ? is it work well?

 

[BAretired]

Can you post the sketch in PDF format? I do not have autocad running at the moment.

BA

 

[a7x1984]

What in the world is that foundation supporting, and why are you trying to connect them? Do you have a significant lateral load? My reference to the IBC was not intended to be for any specific paragraph but as a suggested general resource; many general questions can be answered (or the answer's location be referenced) by the building code.

Before you doing anything creative, make sure the code likes the artwork you are trying to wow the world with.

 

[jwilki]

Those are rather odd column locations, is this part of a greater structure? Do these foundations carry a significant moment such that a pad or pier does not work?

 

[hokie66]

a7x1984 or jwilki,
If the OP can't give us a PDF format version of his sketch, maybe you can, as you seem to know what he is talking about.

 

[a7x1984]

Darn...I was just about to go to bed!

Before you doing anything creative, make sure the code likes the artwork you are trying to wow the world with.

 

[hokie66]

Thanks, a7.

ibrahemnasr,
The sketch shows two single column footings with reasonably concentric loading, and two combined footings with two columns each. No grade beams are shown. What would be the purpose of grade beams?

 

[BAretired]

I too question the purpose of grade beams.

Why are the footings not centered under the columns? Should CF1 be rotated similar to CF16 in such a way that the c.g. of footing is in the same location as the c.g. of load?


BA

 

[ibrahemnasr]

thanks for all my friends tried to help me
this sketch is apart of nearly large structure and this large footing dimesions due to large reactions from both gravity and earthquake loads so i want to connect them for some reasons the most important one is to prevent diffrential settlement
for this reason i attach this sketch for the footing to ask how can i put the grade beams especially between the combined footing and the isolated one?what is the best position for the grade beam?if i pit it between the centers of the loads it would be inclined is this true?is connecting the footing from two direction only sufficient or should i tie it from all directions?

thanks again

 

[samnac]

You are trying to prevent differential settlement? Is that based on geotechnical information? I noticed that the footings are not huge they are 5'-6" max.which tells me that forces are not that big. Any way if you want to use grade beams to avoid bigger footings due to lateral forces that is a legitimate reason because they tend to overturn the footings which require either larger footings or combine/connect them with grade beams. It all depends on the magnitude of the forces and the soils bearing capacity and settlement.

 

[BAretired]

If the dimensions are in meters, the footings are very large. What is the meaning of the circled numbers 60 or 100 on each footing?

At the risk of repeating myself, why are the footings not centered under the column loads?

There is not have enough information to answer the question.

BA

 

[a7x1984]

If it is just for stiffening the footings for differential settlement (assuming this is valid), why don't you place them in a manner that the column loads do not transfer a significant amount of torsion to the grade beams?

We definitely need more information, though.



Before you doing anything creative, make sure the code likes the artwork you are trying to wow the world with.