Software Recommendations for Load Take-down 1

[KootK]

I am interested in software recommendations for the sole purpose of load take down. I can design elements all day long but I really dislike tracking loads through complex structures by hand. Tedious and time consuming. And problematic for QC checking I find. To that end, what's your favorite software package in this regard? Additional things to consider:

1) Element design features are nice but not necessary.

2) Two way load distribution would be nice but robust one-way would satisfy most of my needs.

3) Member continuity would be nice but simple span would satisfy most of my needs.

4) Ability to handle lateral loads would be nice but it not absolutely necessary.

5) I want to be able to model structures three dimensionally.

6) Rapid model generation is important. Woodworks has a tool called Concept that is similar to what I want but it's far too slow for model building. Like trying to sign Christmas cards with my foot. Not that there's anything wrong with that.

7) I'd like to be able to handle headers and posts in light framed wood and cold formed metal buildings. Obviously, most software packages do a great job of high-rise towers with regular column grids.

I'm quite familiar with Woodworks, Visual Analysis, CSI offerings, and RISA. Of that bunch, RISA 3D + FLOOR strikes me as the front runner. Regarding #4, Mitek and its competitors have some great software packages but those are not publicly available to my knowledge.



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.

 

[dik]

If complex, can you use RISA 3D or something of that ilk? If fairly straight forward, there's a spreadsheet written by UK Concrete Center that is pretty good. I'll dig up my copy and post it...

Dik

 

[dik]

KootK... this is one of about 40 sheets I downloaded from the site. Others are to British Codes. I've checked it and you should too if you use it.

Dik

 

[slickdeals]

ADAPT Builder has a load take down module that should simply it.

https://www.youtube.com/watch?v=Wz-wQ8LzmNs

 

[SethGuthrie]

We have a lot of users who use Ram Structural System for this, though it can do the steel or concrete design too. I've personally used it for load take-down in concrete, steel and wood structures. Of course, I'm biased.

 

[slickdeals]

The other software we use for load run downs is RAM Concept in combination with using a spreadsheet for doing the tributary area x floor loads and also doing the live load reduction. We utilize RAM Concept for our complex floor plates and apply a 1 psf load. The reaction in kips * 1000 would equate to the tributary area in SF.

The main advantage is that this accurately captures the proper load distribution to the column instead of doing manual trib area calcs. For example, the first interior column would have more loads than the trib area hand calcs. The problem is compounded if the building is only 2 bays wide.

 

[txeng91]

I've used RAM and RISA quite extensively. RAM is great for concrete and steel models that have pretty regular framing patterns but it can be difficult to model more complex frames, also RAM does not support wood design. I think RISA floor+3D is probably your best bet since it supports wood wall elements including openings and header sizing. The downside is that it does not size wood walls for out of plane wind loads last time I checked, which kind of makes the stud analysis useless.

 

[Yt.]

Perhaps you could give a thought on making your own, probably you would if you want it and isn't as hard as it seems. Time consuming at begining but much more time saving when it has grown a bit. For me it was a way to keep notes of my learning, now i just draw most things in autocad and add the needed inputs as planned, trying to automatize it always. i don't regret the effort.

 

[Trenno]

RAM Concept and Spreadsheet. Accurate, transparent and flexible when it comes to varying column locations. Works a treat.

Now if only Bentley released some API functionality for RAM Concept, we'd be set!

 

[KootK]

Thanks for all the recommendations gentlemen. However, I feel that we're mostly picking the low hanging fruit: steel and concrete jobs. It's really the sprawling light gauge and wood projects that represent the bigger (and more obnoxious) time suck for me.

The clip below is from a RISA model for a project that I'm working on. Light gauge walls and steel joists in the wings, straight steel in the core. Two stories up with interior lines transferring out at a partial basement. Modeling so far has been... okay. It was probably overly ambitious to attempt something so messy with software that I'm not all that familiar with any more (lost my modelling V-card to RISA back in 2001).

I've still got a ways to go before I'll know if the model will produce the kind of results that I'm looking for in these kinds of buildings. And there's a nagging voice in my head perpetually repeating the phrase "just suck it up and do it by hand". But, alas, this is an experiment that I feel compelled to try every few years to see if software has yet caught up with my hopes and wishes with respect to how lazy I might eventually be allowed to get.

An interesting conundrum here is the complexity of going back and forth between walls and column down a bearing line. For a lot of reasons, you want a contiguous framing line. It makes deck assignments much easier etc and the model doesn't appreciate gaps in the support line. On the other hand, if I let the walls and columns touch, then they mesh together and what I hope to capture is lost, or at least more difficult to parse out. I'm considering running a gravity version of the model with the shear modulus of the walls tanked so that the adjacent columns might retain their load. I'd appreciate recommendations in this endeavor. There's a "physical member" feature in RISA but I haven't yet ascertained whether or not that would get me where I want to go.

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.

 

[txeng91]

I think unchecking the physical member box should get you what you're looking for. See below.

https://risa.com/news/how-to-model-column-within-wall-risa3d/

By the way if you're a big Woodworks guy, I would definitely recommend Simpson CFS for light gauge sizing. Its very easy to size beams/joists/studs in and also does shearwalls and stud walls with openings and checks everything, including headers and sills, for axial and out of plane loads. Also the latest update lets you do multistory wall elevations.

 

[jayrod12]

Dnlv, that is perfect.

 

[GerryBertier]

I prefer RISA Floor + 3-D + Foundation for my light framed buildings.

For RISA Floor, I model only full height walls. Model beams between them (as the headers), and columns at each end. Any column (or post) within the length of the wall, I split the wall into two.

I then take all the walls loads in the output and create an excel spreadsheet to then use for stud design.

I use the DXF import feature to create the model, starting from the top down, doing most of the modeling within AutoCAD. This allows for easy pasting of elements and confirms which items stack and which load bearing elements are elevated and need support.

I tried doing a load takedown for a light framed wood over PT podium project in RAM SS at my old job, and it was extremely time consuming. RAM does not like elevated walls supported on beams or deck.

With that being said, RAM Structural System is amazing for steel composite buildings. Loved it.

RAM SS foundation plug in is also better than the clunky RISA Foundation isolated spread footing design.

 

[SethGuthrie]

@ Gerry, if you do another Podium with Ram SS take a look at this post for some guidance.

https://communities.bentley.com/pro..._and_design__wiki/10202.modeling-podium-slabs

 

[rn14]

I'm in the same boat. On complex residential projects I find myself using so many different programs and spreadsheets it is a nightmare. I have tried risafloor and 3d for it once or twice but floor can be a real pain with multi-level and pitched roofs. Gerry has an interesting workflow though, I will have to give that a shot.

 

[KootK]

I think unchecking the physical member box should get you what you're looking for.

Maybe. I'm working in RISA floor right now which presents two possible problems:

1) How do I efficiently go around and raise up all of the column top nodes 1"?

2) Much of the "goodness" of RISA floor is contingent on hard defined floor levels. I'm scared to mess with it.

This may indeed be the way to go once I've got some time on my hands to explore it leisurely. 2035-ish.

@Gerry: your work flow is almost identical to what I've sort of arrived at through trial and error. Except that I'm doing bottom up. Not really sure why or if there's an advantage one way or another. How are you handling truss loads for complex roofs? I was able to realize a chunk of what I'd hoped for by modeling my girder trusses and then representing the commons with one way spanning deck. I can pull my gravity and uplift loads out of the model pretty fast this way. With the framing plan already conceptually sorted and the support lines already modelled in RISA, it took me about 45 minutes.

One of my hard learned lessons here has been one that you've obviously already encountered: do all of the drawing in CAD. ALL. Native capability in that regard is almost non-existent. No doubt that's by design but I'd still prefer to be able to do some touchup work without having to re-up the CAD.

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.

 

[txeng91]

I think moving all the nodes up wouldnt be too much of a pain, just grab them all and use the move node tool. But I definitely understand your hesitation in not wanting to compromise the floor model, it might screw with the lateral load distribution and the column bracing, or lead to a never ending string of the dreaded P-delta error. In the past I have also split walls at the columns and separated them by an inch or so, then connected the top of the column to the adjacent walls with rigid links, obviously that would be rather tedious at the scale your working on.

 

[gravityandinertia]

Just to chime in a tangentially related thought here about the current state of the software. Many people find certain softwares useful, but too much of a pain in certain aspects and leave them. This represents a problem, because the best people, the ones who could do the work without the assistance of the software are no longer giving the software companies feedback on how to improve the product, which hopefully would make the industry (structural engineering, not software) more profitable. Of course this is easier to say than practice, while waiting for your suggestions,and paying subscription fees.

Anyway, just something to think about and a reminder if you want the software to improve, let the companies know the features you want.

 

[KootK]

I think moving all the nodes up wouldnt be too much of a pain

Perhaps not. FLOOR is built around the column stack rather than the individual column. I'll have to do some exploring to see if that makes things easier or harder.

Just to chime in a tangentially related thought here about the current state of the software.

FWIW, I welcome moderately related digression in my threads. Management may disagree however.

You couldn't be more spot on in my case. I essentially intend to use software to obviate the need for junior engineers altogether. That may not be fair to the industry as a whole but, unless I miss my mark, it will be wildly cost effective for me. When/if I'm a bigger entity, I'll jump back into the tutelage game.

And you're right on the feedback front as well. When I first dove in to RISA, the first thing that occurred to me was "man, there's some low hanging fruit here for potential productivity improvements". I'm a former database programmer so, at the risk of tooting my own horn, I've got a better feel than most for what is possible/easy. And that's not to sound critical of RISA. I purchased their package at the cost of a semester's tuition for one of my kids because I thought it was the best alternative given my needs. And I still think that. Nothing's perfect. But yeah, the feedback is a classic tragedy of the commons problem. I even sat down to write the email before thinking to myself "I'll waste a billable hour on this and it'll probably just get added to some 5000 item long list of stuff RISA might consider for 2030". And that's where I stopped. Additionally, something like RISA is clearly built around an anticipated user work flow. In six months, when I'm better adapted to that, perhaps I'll view some of my gripes differently.

A few people have mentioned trusses above. This article may be of interest: Faux Truss Modelling. I know that I could use some help with it. For MPCWT, I don't see a need to model the top and bottom chord separately as those kind of trusses are usually just a bunch of simple span beam-ish things where the top and bottom chords always start and stop at the same place. Different story for a Rafter/Ceiling joist setup. One thing that I currently don't understand, because I haven't gotten that far, is how RISA 3D will (or won't) be able to sort out lateral loads on a pitched roof that I haven't modeled as pitched. No such thing as a sloped diaphragm in RISA floor to my knowledge. If anybody wants to indulge my laziness and chime in on this before I do my own due diligence, it would be appreciated.

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.

 

[gravityandinertia]

@KootK

Any software company has a long to do list, however from my experience many of these to-do's are generate internally based on what the company "feels" customer want. It's amazing what happens when a couple customers send the same idea, how it gets prioritized.

I've worked in this realm and there is a secret to getting your recommendations heard. First, spell out your issue/feature, picture and clear description of how it works, clearer the better, treat it no different then trying to present a clear idea to a contractor. As you said you have programming experience, use that as a guide and make your best estimation about the effort involved. After that, tell them how much time savings it would mean to you and others like you. This allows them to judge the marketability of the feature to their audience, and finally, use your considerable reputation on eng-tips.com to get other to write in seconding your enhancement request. While nothing moves at the speed we like it to, if you follow this advice for your top 5 enhancement ideas/year, you'll likely start to see things you want in the software materialize.

You've essentially done the business case for them. They can see that it is justifiable to spend time on it because of the balance of time, marketability and popularity.