Aluminum Member Design

[MacGruber22]

Has anyone else, at one time or another, pulled their hair out trying to develop spreadsheet-based design of aluminum members? The elements of welded aluminum members are the worst! Any good ideas out there? Currently, I am working around a multi-workbook set-up where you progress from general input workbook through material prop file, flexural, etc. All the workbooks are linked together, but I find the relative links to be a pain in the arse. I constantly am having to re-connect links that I thought were supposed to be relative. Maybe there is an excel setting that I am missing for forcing relative links to remain as such?


-Mac

 

[Bagman2524]

I use "Copy" and "Paste Special" to create links between cells in Excel and a specific position in a Word document. But I'm not sure if that's what you're looking for.

Nearly all men can stand adversity, but if you want to test a man's character, give him power. Abraham Lincoln

 

[SwinnyGG]

Maybe this is a ridiculous question.. but why don't you just merge your many workbooks into one, so that links between sheets don't break?

Excel spreadsheets can get VERY large before they bog down modern computers, as long as you're using simple value calls and not a ton of macros.

 

[MacGruber22]

Bagman. Yup - paste link. What I am saying is that excel seems to not be consistent with whether it retains the link as relative or absolute.

jgKRI - Well, my experience has been the opposite even with simple cell formulas. Maybe that is just my nice new 6 core 16 gig dell... :/ The other thing is that it makes it super hard to work on when I can't have more than 1 worksheet on another monitor.

Frankly, I am mostly just venting about comprehensive aluminum design not being readily part of structural design packages.

-Mac

 

[wannabeSE]

If you want to solve your spreadsheet problem, you might try the Engineering Spreadsheet forum:

http://www.eng-tips.com/threadminder.cfm?pid=770&page=1

 

[appot]

when I can't have more than 1 worksheet on another monitor.

Open multiple instances of excel, as opposed to multiple workbooks in the same instance. Then you can even have two (or more) workbooks with the same name open.

 

[MacGruber22]

Good point, wannbeSE.

appot - I will give that a try. Thanks.

-Mac

 

[DETstru]

RISA does aluminum design very well.

 

[MacGruber22]

DET - really? I don't remember that being apart of RISA. Is it a newer feature? I haven't used RISA in 7 years.

-Mac

 

[Celt83]

If I recall RISA will do the member designs but be careful with any elements that are going to have welded connections as I do not believe RISA will explicitly check that the stresses at the ends are acceptable for the reduced material capacities.

 

[KootK]

If you can find me, you can take my copy of RISA for a lengthy spin with the aliminum module. Subscription licensing.


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.

 

[DETstru]

Mac, you just barely missed it! Aluminum design was introduced in 2010. I thought it was later but I just looked it up.

Celt, you can design for reduced properties by splitting the member near the weld locations and using a different material property. Not necessarily that streamlined but it's how RISA recommends you do it.

 

[Celt83]

DETstru:
simple enough solution. we've done that method before tricky part is always remembering to override the unbraced length of the main member chunk assuming you split it at any meaningful distance away from the supports.

 

[DETstru]

I agree, it's not great.
Luckily I don't do much aluminum design so I don't have any complaints. Just occasional small component on larger projects.

 

[Scratch3r]

Aluminum design is such a bear at times. In Canada,they just last week added a CSA standard for aluminum design to follow that includes screws .

I have tried to put together a proper spreadsheet on previous jobs but the situation becomes so specific that I can't reuse it.

 

[MacGruber22]

KootK - that is very generous of you. I think I will take you up on that offer. We have been considering getting RISA for our podium buildings. Maybe this will help make the case stronger. How shall we do this?

Celt83 - I would imagine that it only allows applying weld-affected properties to the entire section in that subdivided member. The ideal software would account for per element weld-affected area and use the weighted calculations to determine the average cross sectional properties. I doubt RISA can do that (yet). Josh Plummer to the rescue! That said, I guess you could deal with those local element problems on a case by case basis if you really need to squeeze out all the capacity you can get. The other thing I realized is that for exposed, uncoated aluminum lower stress alloys and tempers tend to be used because of better finishing properties. It is a pain in the arse when you have 3 ksi allowable to work with! And of course, the manufacturer's drafter/designer already take a stab at the proportioning of members/thicknesses, etc. so their quoted prices revolve around that - they get really cranky when we want to upgrade wall thicknesses and such. Plus, they hate fasteners! Weld, weld, weld. My oh my...

The overarching issue for me is that our firm is always trying to get into specialized areas to corner the local market. Our true specialty is concrete parking garage design and repair, aside from typical large building design. The ambitions have resulted in looking to specialize in delegated aluminum railing, canopies, etc. I was tasked with becoming the specialist in Aluminum design and to develop a spreadsheet-based program to automate the process. As I started learning about Aluminum design, I quickly realized that this venture was a mistake without investing in tested and maintained software. Of course that isn't going to happen, but the specialty goal is still is being pushed forward because the fabricator has gotten buddy-buddy with our president (of course with promises galore). Imagine this - the first project I had lost money. Who would have thought, while trying to develop a generalized program, meet the deadline, and manage all my other projects. I know you all are familiar with this pain - it is the inevitable struggle.

-Mac