More than one column on a baseplate.
More than one column on a baseplate.
(OP)
Good Afternoon Gentleman,
Have you ever encountered a situation where you have 2 columns extremely close together, where you could combine baseplates? The first thing that comes to my mind is that the columns could twist the baseplate and cause some strange eccentricities. Have you done this before? If not, what are your thoughts?
Have you ever encountered a situation where you have 2 columns extremely close together, where you could combine baseplates? The first thing that comes to my mind is that the columns could twist the baseplate and cause some strange eccentricities. Have you done this before? If not, what are your thoughts?






RE: More than one column on a baseplate.
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com
RE: More than one column on a baseplate.
RE: More than one column on a baseplate.
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com
RE: More than one column on a baseplate.
RE: More than one column on a baseplate.
RE: More than one column on a baseplate.
RE: More than one column on a baseplate.
I thought you were designing a building and was about to chide you for not using the direct analysis method or otherwise considering P-Delta effects. Not as applicable to a non-building structure where second order effects are often negligible and your approximate effective length value is totally appropriate.
It's been a while since I considered multiple columns on a baseplate but I suspect SAIL has the best way to approach it. Support the columns on some sort of grade beam, dunnage, connection system thingy that makes them act as one unit and then provide a baseplate for that single unit. Will also have the benefit of reducing your unbraced length of the columns. However, I doubt it will be any cheaper than just up-sizing the columns.
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com
RE: More than one column on a baseplate.
Dave
Thaidavid
RE: More than one column on a baseplate.
Mighty,
I have never done a building more than one story, never had to use those methods. I would like to learn... and resources are still available. I will learn this eventually but I haven't had enough time and guidance as a young engineer to move on to those more complex methods. So I use the approximate values for my structures, which is what I learned in school a couple years ago. =)
Thai,
I am unsure how to go about doing that. I guess I would have to go back to the old structural analysis book.
RE: More than one column on a baseplate.
RE: More than one column on a baseplate.
Here's a ton of examples for the direct analysis method: http://media.aisc.org/NASCC2015/350325-N18A.mp4
There's a ton of great videos on this from other NASCC lectures, you can find them all here: https://www.aisc.org/searchtaxonomy/conproceedings...
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com
RE: More than one column on a baseplate.
I didn't know it was a bad idea to use effective lengths for column design for multiple story buildings! Guess I better watch the lecture also, thanks for posting!
RE: More than one column on a baseplate.
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com
RE: More than one column on a baseplate.
Jason McKee
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RE: More than one column on a baseplate.
I've gone over the videos you showed and I've got a question:
Lets say you have a 40'-0" column you're analyzing with DAM and you split it into 4 segments. For strength checks of the column would you use KL=10'-0", or KL=40'-0"?
Is more information needed, such as bracing points, or do you not need to worry about bracing points since K is always 1?
RE: More than one column on a baseplate.
RE: More than one column on a baseplate.
This is the same for both DAM and the effective length method.
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com
RE: More than one column on a baseplate.
The columns would have to be tied together somewhere near the top, otherwise the plate will get bent in transport or erection.
RE: More than one column on a baseplate.
One more question:
Even if you have a cantilever column (like a flag pole), you just apply the notional loads, reduce the stiffness, and still have K=1.0? I watched all the videos you supplied (thanks for those!) , but would just like to confirm this.