Best Software for Full Concrete Building? 1

So, usually the structural model includes the superstructure and there is a separate model for the foundation. That's generally good practice in my opinion.

If you are not REALLY experienced in modeling concrete structures and foundations, I would strongly discourage you from including the foundation and the superstructure in the same model.

For structures with concrete walls, floors, beams and such, I'd suggest ETABS as an excellent tool. Obviously, there are other programs that compete with ETABS that may offer similar capabilities. I'm just not familiar with them.

Caveat, I work for the company that sells ETABS. So, I can be considered somewhat biased on this subject.

ETABS w/SAFE for me too. I like RAM ConcePT best for slab design but as a whole suite, it's the CSI stuff.

Can you walk me through some of the advantages of decoupling the foundation. This is a multi domed full concrete structure and all foundations are on a mat/raft. It's European style design/contrstruction. In fact they are flying in a contractor from Greece to build it.

I second using ETABS and SAFE. I'm not a fan of Bentley because of their predatory licensing, and I haven't used RISA.

I haven't ever modeled foundations together with a structure. I'm sure ETABS can do that with spring supports. But anyway, I'm guessing the main driver is speed. Mat foundation design is nonlinear by nature. Then the whole structure becomes a nonlinear analysis, which considerably increases the workers' time and computer time. It takes my very fast computer about 45 minutes to run nonlinear analysis on a relatively simple building, without having soil springs. And in this case, I simplified the load cases quite a bit. In higher seismic design categories, I'm sure it's more complicated.

grogannc: Can you walk me through some of the advantages of decoupling the foundation. This is a multi domed full concrete structure and all foundations are on a mat/raft. It's European style design/contrstruction. In fact they are flying in a contractor from Greece to build it.

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First, I'm curious what you hope to accomplish by modeling the foundation with the superstructure.

My thinking is this:
1) When we model the superstructure separately we generally go with some basic assumptions that the foundation provides rigid support to the structure. This is not explicitly true. However, my basic premise with structural modeling is that you should always start with the simplest model and make sure your design concepts 100% with that simple model. When you add modeling complexity, you often end up making your model LESS accurate than it would be if you kept it simple. I'm not against having complex models, but I prefer to have a parallel model with simpler modeling assumptions. If the results of the two models are significantly different it is really important to understand why.

2) Soils are incredibly non-linear and not in cleanly defined ways. I could do a nonlinear "push over" analysis for a moment frame building and I can see exactly when and why my various moment connections go non-linear. There are good code based definitions for how that nonlinearity should be modeled. I don't believe we (as an industry) have that same type of clean understanding of soils. Maybe if you're both a Geotech and Structural Engineer you could have a better understanding. But, I don't generally trust the numbers my geotechnical engineers give me to be reasonable approximations for my models. Yes, they are good numbers to make sure I don't get soil failure or unreasonable settlement. But, I don't trust the behavior to be accurate enough to IMPROVE my structural model.

3) Part of this is me just being a bit "old school". I haven't generally done this. No engineer that I know does this on a regular basis. There are times when I have modeled soils, but that's usually for cases where the soil dynamics are the PRIMARY design consideration. Like foundations for dynamic equipment.

Another vote for ETABs for Vertical and Lateral Frame Resisting Concrete systems. SAFE is reasonably okay for foundations, less so for elevated horizontal design. RAM Concept is great for both conventional and post-tensioned reinforced concrete design and ,in my opinion, is the best software at what it does. Although there are some challenges, my typical design stack is ETABs for the primary building, Safe for foundations associated with the LFRS, RAM Concept for slab design and or unique column foundations.

milkshakelake said:

I haven't ever modeled foundations together with a structure.

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I just went through an exercise where i included the shallow foundation as part of a deflection sensitivity analysis for a large cantilever canopy through ETABs, looking at the impacts of column fixity, and foundation flexibility. ETABs Ultimate has some good tools in which I will probably design these foundations for strength in that program in lieu of taking them to SAFE. On a typical building design, I have not included foundation as part of the analysis model before.

JoshPlumSE said:

However, my basic premise with structural modeling is that you should always start with the simplest model and make sure your design concepts 100% with that simple model. When you add modeling complexity, you often end up making your model LESS accurate than it would be if you kept it simple.

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This is fantastic advice, and one of the biggest mistakes junior engineer makes. Complexities should be added across modeling iterations, so that you can study and understand the impacts and results.

I would suggest Sofistik. Very powerful and neat.