Which software is able to design multi-level strip foundations? 2

[Sooshiant]

I use CSI SAFE 14 to design foundations usually. SAFE claims it can design foundations in different elevations, but it can't. So I need to know which software is able to design multi-level strip foundations?
In attachment I've provide a simple example to know what I'm talking about.
Any help will be appreciated. Thanks

 

[oldestguy]

What did engineers do before computer programs for this situation? Maybe that is your option.

 

[hokie66]

Exactly, oldestguy. Software doesn't design anything, it helps us with our computations.

 

[JoshPlumSE]

My tendency is to look at these elements separately.

Level 1 would be designed on it's own for the most part.

The retaining wall would be designed to resist the active pressures of the soil and the reactions caused by level 1.

Level 2 would be design to resist the reactions from the retaining wall and whatever vertical reactions directly apply to it.


I suppose if you were really sophisticated you could get into some serious soil-structure interaction issues for this foundation. But, that's usually PhD thesis time.... And, isn't something most people do for common structures.

 

[BUGGAR]

That looks like a relieving platform for a retaining wall design type structure similar to what I've seen in seawalls. How will you design this structure either with or without a computer?

 

[Ron]

Like hokie66 and oldestguy, I use software as an analysis tool, primarily. I prefer to do the design manually. While some software packages do a very credible job at design (RISA 3D for instance), I still prefer the flexibility of using my judgment even if I use the software for analysis and even design checks. That gives me a better understanding of the structure and its interaction with loads, restraints and reactions. After all, I'm responsible for the design....the software producer is typically not responsible for my use of their software.

 

[KootK]

You could model it in safe ignoring the step other than to place a continuous flexural hinge across the footing to represent the step. Your proportions do not suggest the capability for flexural continuity across the step. Will the soil behind the retaining wall be backfill? If so, that may warrant some consideration with regard to soil modulus etc.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Sooshiant]

Thanks my friends. Me myself model it separately then add retaining wall, but this way doesn't see the interaction of two slabs. Here almost all structural engineers do this and accept the approximation. Some others design two level in one but I think its not true.

I didn't hear the method KootK is talking about, then I should check it. It seems your procedure is more accurate than mine.

 

[L0k]

In my opinion all the structures should be divided in 3 individual structure: structure level 1, retaining wall & structure level 2. Each structure should not connect each other to avoid the future settlement nor displacements. The structure level 1 will be influencing by the structure level 1 settlement and the retaining wall deformations. So there should be an allowance to repair the services between the structures.
I prefer to use piles for the structure level 1 and embedded below the retaining wall failure line.

 

[Okiryu]

I would also analyze them considering 3 different structures:
1) Level 1 : eccentric loaded foundation
2) Retaining wall: considering soil lateral pressure and also pressures from level 1 foundation
3) Level 2: conventional foundation
I would also use a joint between level 1 and the retaining wall.

OR 2 different structures:
1) Level 1 : eccentric loaded foundation
2) Retaining wall and level 2: considering level 2 as the heel of the retaining wall
Again, I would use a joint between level 1 and the retaining wall.

 

[Sooshiant]

L0K and Okiryu
If there would be such a great financial or architectural feasibility the most easiest way was to design both slabs in one then fill the higher part to reach the needed level, even in this case you had less torsion in upper structure and everything was OK.

Ron
RISA couldn't help too.

 

[Sooshiant]

Beside going to Moon and Mars or making atomic bomb I don't know what the mankind has done with this. Since we can see it in all foundations like in elevator well and mechanical rooms or etc.