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NEW BUILDING BETWEEN TWO ADJACENT EXISTING BUILDINGS
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es_jayakumar
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PostPosted: Sat Oct 06, 2018 11:19 am    Post subject: Reply with quote

It is a good suggestion to lift the column position inwards and provide cantilever beams and slab to maintain the required floor area. Provision of raft slabs can be thought of, if the bearing area of strap foundation envisaged is falling short, in that case.

E S Jayakumar
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ishata_gupta
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PostPosted: Mon Oct 08, 2018 10:54 am    Post subject: Thank You for taking out your time to reply! Reply with quote

Yes the buildings are very old and in use.
i was recommended by an experienced structural engineer to chisel the brick foundation for only the width/depth of the column and place the footing just below the existing brick foundation so that the load is transferred from the brickwork to the new concrete footing.
Also i was advised to place dowels in the footing and hammer them in the masonry for load transfer.



es_jayakumar wrote:
Are the adjoining buildings in use ? You have to keep two aspects in mind, in this regard :
1. Chiseling the foundations of the existing buildings will not only reduce the bearing area, but also make the loading on soil eccentric. Impact while chiseling can damage the adjoining portion of masonry also.
2. When you place the new foundation abutting an existing one, the soil may get over-stressed due to merging of pressure bulbs.

E S Jayakumar
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ishata_gupta
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PostPosted: Mon Oct 08, 2018 11:04 am    Post subject: Reply with quote

Yes! The first idea was to shift the columns inward and consider the beams as cantilevered. also since the walls are 13.5" thk, we can have the beams rest on the walls with 7-8" bearing making the beams act as propped cantilevers.

es_jayakumar wrote:
It is a good suggestion to lift the column position inwards and provide cantilever beams and slab to maintain the required floor area. Provision of raft slabs can be thought of, if the bearing area of strap foundation envisaged is falling short, in that case.

E S Jayakumar
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ishata_gupta
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PostPosted: Mon Oct 08, 2018 11:11 am    Post subject: Re: NEW BUILDING BETWEEN TWO ADJACENT EXISTING BUILDINGS Reply with quote

i was recommended by an experienced structural engineer to chisel the brick foundation for only the width/depth of the column and place the footing just below the existing brick foundation so that the load is transferred from the brickwork to the new concrete footing.
Also i was advised to place dowels in the footing and hammer them in the masonry for load transfer.

ravee6a wrote:
Dear gupta,

Take the advise of local engineer having experience of such foundation
and soil condition of that locality.
A.Raveendran.

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ishata_gupta
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PostPosted: Mon Oct 08, 2018 11:43 am    Post subject: Re: Border restraint Reply with quote

Thank you for your response Mr. Suraj Sir.

Due to lack of soil report, i'm assuming SBC as 13t/sqm at 5' below NGL (the value usually considered for the soil in this area).


suraj wrote:
Better design a combined footing
Why go 4.5 feet below NGL?
What is value of SBC?
It is OK just to found building at a depth around 1M, if SBC permits
If it is required, apply soil improvement method to raise soil BC
This common wall problem is too old & not required, but authorities do not think
You can also, opt for beam foundation connecting all columns if Combined Footing is not desired
Design as structural beams shall provided a better foundation
Columns to come up from top of beams, with reinforcing starter bars from base of beam
Spread isolated footing not necessary
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ishata_gupta
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PostPosted: Mon Oct 08, 2018 11:46 am    Post subject: Re: NEW BUILDING BETWEEN TWO ADJACENT EXISTING BUILDINGS Reply with quote

Yes! The first idea was to shift the columns inward and consider the beams as cantilevered. also since the walls are 13.5" thk, we can have the beams rest on the walls with 7-8" bearing making the beams act as propped cantilevers.
But then i was told that this chiseling of brick foundation for column footing is a very common practice in case of common load bearing walls.

[quote="prof.dsp"]It's better to avoid chiseling by shifting the columns inwards.

On 6 Oct 2018 06:29, hemaraj rv <forum> wrote:
Quote:
       check the soil property and if possible construct same brick foundation partially for adjacenrt columns  On Wed, Oct 3, 2018 at 3:53 PM ishata_gupta forum@sefindia.org)> wrote:  --auto removed--

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suraj
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PostPosted: Sat Oct 13, 2018 12:51 am    Post subject: Re: Border restraint Reply with quote

If you are sure that SBC is adequate to found at 1M level below NGL, better go for combined footing. Make sure that it is not clay & if it is, better provide soil improvement first

ishata_gupta wrote:
Thank you for your response Mr. Suraj Sir.
Due to lack of soil report, i'm assuming SBC as 13t/sqm at 5' below NGL (the value usually considered for the soil in this area).


suraj wrote:
Better design a combined footing
Why go 4.5 feet below NGL?
What is value of SBC?
It is OK just to found building at a depth around 1M, if SBC permits
If it is required, apply soil improvement method to raise soil BC
This common wall problem is too old & not required, but authorities do not think
You can also, opt for beam foundation connecting all columns if Combined Footing is not desired
Design as structural beams shall provided a better foundation
Columns to come up from top of beams, with reinforcing starter bars from base of beam
Spread isolated footing not necessary
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