Matt Foundation Design Program 2

[msquared48]

Can anyone suggest a very user friendly Matt Foundation design program to purchase?. Got one coming up and will need to get a program.

Does Enercalc do this?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[strucguy]

I use PCAmat before and was happy with the end result. It you are willing to invest more....you can probably look into SAFE that is more robust.

 

[spats]

Another vote for PCAmats.

 

[johnbridge231]

A cheap solution would be to get the output stresses/forces at characteristic cross section (for example at column, wall locations, etc.) from your analysis program and check the adequacy of that sections as per the relevant regulation.

Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis

http://www.engissol.com/cross-section-analysis-design.html

 

[WWTEng]

PCAMats. Even did a structural slab supported on piles with this. Easy to use, even for me

 

[JoshPlumSE]

Obviously, I'm not exactly an unbiased observer (as I work for RISA). But, you might want to go with a program which uses a "thick plate" formulation. And, I'm pretty sure that PCA mats has a thin plate formulation that doesn't necessarily work well for thick mat foundations. See the paper below.

http://www.risa.com/documents/pdfs/FiniteElementConsiderations_MatFound.pdf

The paper was written by one of our developers in 2007. The intent of the paper was to point out that this particular flaw (thin plate formulations) existed in some of the popular Mat design software.

FWIW: I have some personal experience on this issue as well. When my old employer was building a new office, our department head was ranting about the program they used for designing the foundation (I believe that it was PCA mats). Specifically, the foundation needed to be redesigned at the last minute because the design program used a "thin plate" formulation that did not account properly for out of plane shear in thick plates. My group (which was in charge of validating structural software for the company) got some heat for not having pre-identified the flaws in the program.

 

[hokie66]

Interesting, Josh. But the way I read the paper which you attached, the difference is that your model, for some reason called 'thick plate', copes better with the nonuniform loading as the soil deforms, thus gives smaller bending moments. The other program with the 'thin plate' assumption would thus be somewhat more conservative. Correct?

 

[JoshPlumSE]

Hokie -

For bending moment, I believe that would be true. But, the shear forces could be under-estimated. In that way, you might be conservative with the amount of reinforcement, but unconservative with the thickness of the slab.

We're not talking about giant, huge discrepancies here.... maybe 15% for a pretty thick mat like the example given in the paper. And, the dimensions and such for that slab were probably chosen to give a higher than normal discrepancy. So, it's not one of those "stop eveything" issues that we sometimes see. For most foundations the discrpancies are small enough that it's really not an issue of safety

It's just one of those things where true FEM guys wonder why you would use that type of element for thick mats. Elevated slabs and thinner slabs would be fine. But, thicker foundations (like you sometimes get with pile foundations) could be problematic. I know I cringed a little when I read that WWTEng said that he had used PCA for a pile supported slab.

 

[hokie66]

No, the total load is unchanged at a given column, and because in your model the soil pressure is higher in the vicinity of the column, lower punching shear stresses would result. "True FEM guys" can wonder all they want, but I doubt that many of them live in the real world of mud and concrete. A mat foundation is not a finely tuned machine...it is a rather a brute of a transfer slab which is dependent a lot more on competent execution than on design refinement. Not criticizing your program, but the other way has served well for a long time, and I believe is a bit more conservative.

 

[Enhineyero]

I would recommend using safe. basically it is a FEM program designed for plates. it is quite user friendly. It also has a good graphic presentation and yields reliable calculation outputs. You may also use it for designing slabs and beams.

regarding the price...well that is a different storey

 

[Enhineyero]

I cant edit my post

*storey - story

SAFE is by CSI

 

[JoshPlumSE]

Hokie -

I get your point. You're assuming that any flaws in the FEM analysis are minor and that they'll tend to be conservative. And, in the "real world of mud and concrete", you think a thin plate analysis is good enough. That's a valid argument. After all, how accurate can ANY analysis be if it doesn't account for soil non-linearity or interaction with the super-structure or such? There are so many simplifications and unknows in foundation design that we shouldn't pretend that we know the "true" results to 8 significant figures. I get that.

Even so, it still seems odd that some programs use a tool (thin plate FEM formulation) that has been obsolete for so long. It's not like the thick plate formulations are new. They have been around since at least 1990, probably earlier. And, for a FOUNDATION program to ignore these elements and use a thin plate formulation seems quite odd to me. Odd, not negligent or irresponsible. Just odd....

 

[hokie66]

Well, my point is that design of mat foundations using the assumption of uniform soil pressure is somewhat more conservative than using the assumption that the soil pressure varies. It is obvious that the pressure on the soil varies, just as it does under any spread footing. But using a flat plate program with uniform loading is not wrong, just a different model than the "thick plate" model.

 

[SethGuthrie]

A bit late to the party, but I can recommend Ram Concept (but like Josh, my recommendation is not unbiased).

 

[InDepth]

SAFE is by CSI

 

[jberg]

I would recommend VisualFoundation from IES (

http://www.iesweb.com).

Very short learning curve and does most of what SAFE does, but much easier to use than SAFE in my mind.

JWB

 

[ChrisMagadiaCom]

in my 10 years in the middle east with predominantly mat or raft foundations in building structures...we normally use safe software by csi...it is quite good and comes handy once you have completed your etabs superstructure model

chris magadia

http://www.chrismagadia.com

ChrisMagadia.Com - The Structural Engineers' Forum and Resources Website. Civilizations owe its existence to Structural Engineering. Do you Agree?

 

[UcfSE]

I used RAM Concept. It was exceptionally easy for a complex load arrangement since I used RAM to design the structure. It was a matter of importing a file and all of the loads and data came with it. I checked all of the input, how forces came in and such, and found it imported quite well. There were a few things I wish it did for me (maybe I couldn't figure them out) but overall I was happy with the results. I haven't used SAFE but I've heard a lot of good things about it as well.

 

[IsaacStructural]

I vote for RAM concept on the higher end. It has the added benefit of being useful for elevated slabs and post tension slabs.

M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)