Irregular Combined Footings

[strawhats2000]

Hi,
I have seen that footing in a structural plan. When I came across such I usually combined the footing to create a bigger square or rectangle footing which is much easier to detail. However this engineer combined it in a L-shaped footing. I will like to know whether building codes allow for this and whether this is ok. Thanks.

 

[HTURKAK]

Apparently the spacing btw the top row columns seems 600-700 mm and the tie beams have ftg . Are the continuous footings wall ftg? .

If so, the ftgs probably designed as wall ftg rather than combined one. Y12@150 reinf. used everywhere implies the designer is generous.

...



He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 

[JoshPlumSE]

I generally prefer it when a drawing clearly labels something as a plan view and section cut. Those images are both plan views.... Right?

Regardless, I don't know why a building code wouldn't allow something like this. Early in my career I worked for a company that did a lot of foreign project. Regardless, a normal project we would have used the same five or 10 footing sizes for every foundation we could. Construction could re-use the forms, save on labor (because the forms would be simpler shapes), save on time. Generally a win-win. The only drawback was we'd oversize some foundations so that they'd be similar to the other foundations in that area.

This was often in locations where labor was dirt cheap. On one project, our client (who was the general contractor) had an odd contract that essentially based their profit on minimizing material costs. Actually, it probably meant that it minimized their losses. Regardless, we our client basically said, "I don't care how much form work we need. We're happy to use 100 different sizes for 100 footings.... If it saves us 1 yard of concrete."

So, basically all our footing were customized sizes and we'd put in goofy shaped footings... just to save a little concrete. We were getting paid by the hour. So, while it seemed crazy inefficient to us, that's what we did.

Still, it was better than the days when the company had done "cost plus" jobs. In those days, the project managers would genuinely encouraged tried to make their project as expensive as possible.... because that increased our profit.

 

[KootK]

There's no code prohibition on L-shaped combined footings but, at the same time, I doubt that the footings that you posted actually are L-shaped combined footings. It's a common practice to allow footings to run together when it's deemed that would be more economical that trying to create a formwork boundary between them. Often, when this is done, the footings are still designed as though they were independent. See the sketch below for one possiblity.

In many scenarios, properly mobilizing a true, L-shaped combined footing would mean mobilizing the footing in torsion which can be a bit of a sketchy situation.