Design of bricks masonry wall footing 1

AsadHayat · Nov 4, 2022

A double storey college building is to be designed. It has been recommended to use continuous brick masonry wall footing in the geotechnical investigation report. Allowable bearing capacity is 0.65 T/sft and minimum depth of footing is 4 feet. Please note that masonry wall will directly rest on the PCC pad as is the case with typical masonry wall footing.

I have considered central 9" brick masonry wall (between two 28'×22' classrooms) for design. I have considered 5" slab that will directly rest on the walls.

I am attaching a file. In this file, I have first calculated loads that the wall is bearing. After load calculation, I have chosen minimum width at which ultimate bearing capacity shall be less than Qallowable. Uniform loads I have considered for the design have been mentioned in the file.

Architectural drawing has also been shared with you. All outer walls are 13.5" thick. Inner vertical walls of classrooms are 9" thick and horizontal walls of classrooms are 13.5" thick. Internal 9" vertical wall has been considered for design.

You are requested to peruse the file and share your opinion on if my load calculation and design methodology is correct or not, and whether for the central 9" wall the width of bricks masonry wall footing that I have chosen is correct or wrong.

Thanks.

Link to file:

https://files.engineering.com/getfi...8287-e00f3db3596a&file=Continuous_Footing.pdf

JedClampett · Nov 4, 2022

Dude, for one, this shouldn't be in this forum, but a more structural one, like "Structural Engineering General Discussion."
But more importantly, this site is not for random engineers (some good, some eh) to review your work. You should have a supervisor or peer to do that. If you don't and have the questions above, you shouldn't be doing the design.

phamENG · Nov 4, 2022

A continuous brick masonry footing? Where is this? We stopped using that style of footing over 100 years ago. Do you not have access to concrete? (This is a legitimate question - I'm sure there are places where people don't, and even here in the US some remote sites may be better suited to bringing in pallets of block on a small trailer than trying to get a concrete truck in...though even in that case I'd probably go for a hand mixer and sacks of ready-mix.)

Lomarandil · Nov 5, 2022

IP says Pakistan, where this type of foundation is still common.

I haven't run the numbers (or checked yours), but I'd wonder about the adequacy of 9" wide footings under seismic load, depending on the details of your site and the compaction that can be attained in the adjacent backfill. 9" brick 4' tall seems like it could have some out-of-plane issues.

swazimatt · Nov 6, 2022

i believe he is referring to a 9" wall with 18"x9" concrete strip footing (like shown here

https://fet.uwe.ac.uk/conweb/house_ages/elements/print.htm

under the "between the wars"

This is still very much common practice in developing countries, however for double story structures we used to increase the strip footing width and reinforce it.

I would hazard a guess that the bricks are fine (if hollow 9" concrete blocks we would concrete-fill them) the footing depends on your bearing capacity and (in my experience) this is generally in non seismic countries. The countries that shake tend to go with raft or conc. column and beam framed structures with brick infill (often non load bearing extruded bricks)

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Design of bricks masonry wall footing 1

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