Practical Application of RAM Concept

[JNEnginr]

Hey Everyone,

I'm writing to see who (if anyone) uses RAM Concept for the design of two-way concrete slabs. I find that the program is able to give me solutions, but not completely practical ones. Is there anyone out there who uses this program to regularly design and compile their drawings? And if so, maybe we could exchange email address to discuss?

Thanks in advance.

 

[Trenno]

I generally like to use design strips for deflections and take design sections (@ critical locations) to design my PT/Reo.

I agree that trying to design reinforcement using design strips is mostly useless.

 

[JNEnginr]

Thanks for the reply.

I guess my next logical question would be, if no one is really using concept, what is everyone using?

 

[Trenno]

No, no. I use RAM Concept daily. My above comments are based on strips and sections in the program.

It just takes time to find out what it does well and what it doesn't do well.

 

[asixth]

It's like any engineering package, if used properly it will help you calculate slab thicknesses and reinforcement requirements but it won't produce detailed engineering drawings. It's still the engineers responsibilty to take the output and detail the slab practicallly.

 

[asixth]

This my experience with RAM and I am saying this on the basis that I use another concrete package for design and detailing the slabs which I believe is a better and more accurate program. And this is using the Australian Code module (AS3600).

RC Slabs
- Gives less deflection than what it should (unconservative).
- Gives higher flexural reinforcement than what it should (conservative).

Post-Tensioned Slabs
- Returns a higher deflection (conservative).

There is no difference in using a design strip or cutting a section for your design. Most detailing comes down to peak flexural design and peak shear design after the slab thickness is established. The peak moments and shears are reinforced and the engineer determines where and how the reinforcement is curtailed back to minimum requirements.

 

[manstrom]

I use it all the time. I don't have any exception to the results. It does take some time to lay out the strips well. I have checked against other calcs previously and come up with comparable designs.

I've designed and built a few dozen of these. No issues. I'm not losing sleep over it either.

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[manstrom]

A few more notes.

Obviously, a rectangular grid works best. Sometimes you get odd reinforcing results, you need to learn how to interpret these and what the "bugs" are.

For weird sized strips and supports, it does take a little bit of judgement to lay out the bar.

But for standard bays and strips, I generally use the results that it provides.

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[JNEnginr]

Thanks for all the replies.

I guess that was the main thing i was looking for. Output. It's an amazing analysis tool, I was just looking for a way to transfer the results it gives into a more practical layout for construction.

I'm new to the program, and of course my first two projects using it had completely irregular grids, so that always makes the learning curve more interesting and time consuming.

Like you said manstrom, it does take a good amount of time, and im worried that spending more time modelling and less time getting practical results.

Do you feel that it handles concrete beam torsion well?

 

[slickdeals]

One of the practical applications of RAM Concept is to generate a finite element mesh for the slabs, which we then import into ETABS.

 

[Titleistguy]

My company uses SP Mats, (maybe known to some folks as PCA Mats). I've designed some large foundations with it, and while it is reliable, it isn't very user friendly.

 

[manstrom]

I find that you need to break down the rebar outputs into 4 views

Long. top bars
Lat. top bars
Long. bottom bars
Lat. Bottom bars

It makes it much easier to read. I also read results between both the Design Status tab and the Reinforcement tab. They should both show the same thing, sometimes one is easier to read than the other.

You can create new plans under layers/new plan

I layout strips using the span / column strip boundary lines and try to have all of my strips as "manual". You can fairly closely match the intended layout on your drawings.

Make sure and assign a bottom mat under reinforcement. This saves a lot of interpretation.

For beams, I assign user rebar as well.

I have worked at firms that go as far as using user assigned rebar for the entire slab. It's a little overkill for me unless I have a complicated area.



When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[bookowski]

asixth - When you say that it gives less deflection than it should what are you comparing this to? Just asking because I use both RAM and SAFE and have found that RAM gives larger deflections than SAFE - so this would mean that SAFE is very unconservative if what you suspect is correct. (There is a big difference in punching shear between the two as well but that's a different issue)

 

[manstrom]

I have been told that the load deformation module in RAM concepts replicates in field measurements fairly well. YMMV.

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[rapt]

Bookowski,

Safe has been reported as having some serious deflection calculation problems in the versions since it started allowing for cracking an long term effects. Grossly underestimating long term deflections. I do not know if they have been fixed.

Before those versions, it simply reported short term uncracked deflections.

RAM Concept gives you several methods of calculating deflections. Only the most complex one gives realistic deflection results, and then only if the designer has selected to include the Mxy effects in design. There have been some suggestions of unexpected effects in deflections in some cases, and some very weird reinforcement layouts in band beam and slab structures.

 

[bookowski]

When did SAFE only do uncracked sections? Must have been quite a while ago. What I know as the 'old' version of SAFE (iterations of V8) still did cracking.

 

[JNEnginr]

Rapt,

I actually spoke to a representative over at Bentley and asked him about the Mxy affect that you just mentioned, and he didnt know what i was talking about. Where is this selection made in the program?

 

[Trenno]

You'll find options to account the Mxy moments under the design strips and sections properties tab.

There are basically 4 options to in RAM Concept... as shown below.

 

[Trenno]

And yes - the default option is "None" - thus ignoring the twisting moments...

 

[JNEnginr]

I did discuss that with him, but he told me that as long as i went into the Mesh, selected the slab, hit properties, behavior and made sure it was set as two-way slab and not no torsion two way slab, i'd be ok. You're saying this isn't the case? So in your column strip dialogue box, you select CS torsion Design to say "As Shear?"