Under reinforced foundation

[Smitash]

Hi,

I have a problem..A contractor has not followed the structural plans and has cast 42 pad footings and columns.Now according to the load that the building will carry some of the foundations are found to be in adequate. Apart from demolishing and cast again, is there any method to remedy this?. Intermediate columns cannot be placed to reduce the loads spread.
Secondly, the Contractor should have placed ground beams. but the latter did not do that and has cast a 6m high column. According to the loading and height of the column, the reinforcement which the contractor has placed is not enough. Can the bars be dowel to place the ground beam?

 

[mylife2014]

Smitash:
The method that i can suggest to you is to retroffit ta affected structural elements.
One type of retrofitting is by FRP wrap.And another is by enlargement..But since you need to cast ground beams I suggest that you enlarge those members in such a way that you can place the ground beams reinforcment inside the additional column reinforcement.

 

[Smitash]

Thanks. For the columns, I am thinking of placing a beam on the 6m high column. The 3m high is below ground below. The height of the first floor will be 5m. At the openings, instead of placing a lintel i will place a beam and thus reduce the height of the column and its slenderness. I am having this complication only with the internal columns, those on the boundary are structurally fine.

If i enlarge the pad footings, I will have to dowel reinforcement into the existing one. Will the foundation be strong enough to support all the loads?

 

[ztengguy]

Seems to me if he had the plans, the plans were clear and concise, I would put it on him to remove and recast.

Or, at least get payment up front to do his engineering work, or have him submit engineering to you for you and the owners approval.

for the life of me, I dont understand why contractors cannot read and follow directions. I understand mistakes will be made, but 42 times?

 

[CELinOttawa]

My mindset usually reflects atengguy's point of view.... However, if your columns can take a shortening (ie: You are in a non-seismic area) and there is the depth below the invert level of the slab, I have had a contractor roughen the surface of the footings, lay the required reinforcing onto the tops, and cast new footings above minus the covering thickness for the underside.

Doesn't fit all situations, but it can be a great trick. Remember: Your starter bars need to be able to develop or be spliced before the topping is cast; Then you may have a bundled bar condition to check.

DO NOT LET SOMEONE ELSE'S PROBLEM BECOME YOUR LIABILITY. Yes, I am yelling as a point of fact. *smiles*

 

[mylife2014]

I agree to the idean suggest by CelinOttawa with regards to casting a new forting above the existing..I have used that in my design before..
But Smitash regarding with your question if that would be strong enough to carry the loads, of course it depends upon on how you do your analysis.Note that you will have now a new embedment depth which one parameter essential in the design.

 

[AELLC]

The way I do this in residential - may not work for your situation - see attach