Pad foundations: No wall connection between

[EngDada]

While about to lay the foundation for a two-floor building, the question came up about whether to ignore excavating the space between two particular foundation columns and to neglect installing a supposedly redundant block wall between them. The two columns in question are under a ~6.25 m ground floor slab under a living room area as indicated by a red arrow in the foundation layout (columns at 5A and 5D).

The reason proposed is that the block wall "will not be load bearing" and so will not be needed and if at all, a grade beam between the columns should serve the same purpose without needing an excavation. However, block wall connections will be provided between the other 27 columns, except for the two in front of the stair case (see architectural drawing) for the same reason.

Does anyone have experience with not connecting such columns with a block wall, and would a grade beam connecting them but sitting on the ground be a necessary replacement or just cosmetic?

This is a concrete block wall house designed to have pad foundations with 29 reinforced concrete columns (225mmx225mm cross sections and 1500mm height) inserted into 29 footings (approx. 1m x 1m x 0.3m). The house itself is about 14m x 13m with cantilevered first floor slabs. Below are the foundation layout, foundation cross-section, and architectural drawings.

 

[EireChch]

Delete this and Post this in the structural forum for better response.

 

[JoshPlumSE]

Does anyone have experience with not connecting such columns with a block wall, and would a grade beam connecting them but sitting on the ground be a necessary replacement or just cosmetic?

There are plenty of times when a grade beam is useful, but where it isn't part of the vertical load carrying system. Some quick thoughts:
a) The most common reason is for a steel moment or brace frame where it is used to tie the two columns together. I don't think that would apply in this case.
b) Similarly for a wall system, you might want to tie different walls together laterally. Kind of like a drag strut, but at the grade level.

Barring those reasons, I cannot see a great reason to have a grade beam / strap foundation in that location.... unless it's being used for vertical support.