Water freezing in HSS Column
Water freezing in HSS Column
(OP)
Does anybody know of any resources regarding the effect of water freezing in side an HSS column??
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Water freezing in HSS Column
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RE: Water freezing in HSS Column
Mike McCann
MMC Engineering
RE: Water freezing in HSS Column
Yes, it's melted snow that refroze.
RE: Water freezing in HSS Column
RE: Water freezing in HSS Column
There was permanent deformation to some of the columns. We just need to know how much to reinforce the damaged and non-damaged columns to prevent this.
So essentially, what does the freezing water do to the capacity of the HSS column.
RE: Water freezing in HSS Column
For non deformed columns I don't think the freszing of the water inside changes the capacity at all.
I'd make a two piece rigid template out of plastic or metal with the exact outside dimensions of the HSS. Snap it over the column and check for gaps or bulges.
RE: Water freezing in HSS Column
Thanks!
How about this, if the column was a circular section, would it be safe to check the hoop stress of the column and do a combied loading unity check?? Sorta like a bending and compression check.
The columns I'm dealing with are currently square section, but if it's gradually changing to circular section, wouldn't that have similar strength.
Not sure if I'm making sense of if this is even logical, but I'm trying to justify not having to remove these columns, or just make minor reinforcement.
RE: Water freezing in HSS Column
RE: Water freezing in HSS Column
Structural Engineers get to sleep?? :)
You make a very good point. I'd still like to at least try reinforcement before replacing the column.
@JedClampett
Your idea sounds like a good one. Kinda like wrapping the column up with more steel.
RE: Water freezing in HSS Column
You could theoretically reinforce the column to repair it. But these type repairs are tougher in practice than just sketching it up. I think if you talk to a contractor, you'll find out that it's easier, more reliable and cheaper to replace the whole column than to reinforce it. Or you could cut out the damaged section and full penetration weld a new section in. Note that the back of the weld will be inaccessable, so your weld procedures and metal thickness will be restricted.
RE: Water freezing in HSS Column
RE: Water freezing in HSS Column
RE: Water freezing in HSS Column
Avoiding repetition of water intrusion is the important thing. I would look at grout injecting the columns. That will help slightly with the compression capacity, but I wouldn't count it.
RE: Water freezing in HSS Column
Unfortunately, one of the columns has deformation for almost the entire length of the column.
@hokie66
There is no fracture or separation of the base plate noted. Your thoughts on this does make sense, but I need some way to justify it. Not sure if it's as simple as assuming a larger section modulus. But a lot of steel does go through cold-forming to create new sections, I suppose this is no different.
I guess another question also, is a constant freeze and thaw of the water over the seasons going to be a bad thing for the column. If your section modulus idea is right, then I should just check to see if there is enough capacity of the section to withstand the hoop stress from the freezing of the water, because every time it thaws, it will take the new shape of the column and freeze again and expand.
RE: Water freezing in HSS Column
Keep the water out, put in drain holes, or fill the column with concrete or Styrofoam.
RE: Water freezing in HSS Column
applicable. We were surprised with the damage we saw?!
Play it safe, not a place to try to save.
RE: Water freezing in HSS Column
As long as it hasn't split or lost it's geometric properties, I would accept it as is. But it is imperative you find a way to avoid repetitions.
I should say I had to do a lot of checking when I had something similar but on a much bigger scale happen. The analysis said ain't steel wonderful, it is so forgiving.
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Water freezing in HSS Column
First off, one cannot assume this section has any kind of increased capacity. That is flat out preposturous.
This deformed compression memeber is subjected to Pdelta and pdelta (big and little) that are way outside of those anticipated by original member out of plumbness and camber/sweep. Now you have moments induced wildly about the length from eccentricities in the shape.
Secondly, HSS is not "squeezed" into a sqaure. They are rolled and welded. There is no extrusion process and they are not entirely cold worked as in this case with the water freezing and distorting the shape. There is some cold working in the forming process, but that is controlled and at least uniformly accomplished.
Where is this column located in the the structure?
What type of structure?
i say replace it.
RE: Water freezing in HSS Column
There are 4 columns that are currently deformed and they are all interior columns of a non-heated building.
Thanks for everyone's feedback. Still not sure what we're going to do, but all this information is definitely helpful!
RE: Water freezing in HSS Column
RE: Water freezing in HSS Column
They are 178mm x 178mm (7" x 7")
Also, here in Canada some square HSS are formed from cold-forming a circle section to a square section.
RE: Water freezing in HSS Column
Our parent company owns a tube mill, and I have seen it run.
RE: Water freezing in HSS Column
I am having trouble understanding this statement. Does that mean the column was totally filled with water?
If you drilled some drain holes near the bottom of the column, would it be possible to prevent water from accumulating inside the column? If you can prevent future freezing inside the column, then I tend to agree with hokie that there is no reduction in capacity, but before committing fully to that theory, I would like to see a photo of the column which is deformed throughout its length.
BA
RE: Water freezing in HSS Column
There are going to be local Pdelta effects, but I took this to be a "long" column, where the column stress is based on kL/r, not the limits of the material.
I have performed analyses of such cases, introducing the the offsets and modified section properties at the appropriate places. The effect on the column buckling load was negligeable, and the local material stress limits were not exceeded by the local Pdelta effects.
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Water freezing in HSS Column
Yes, the column was nearly entirely filled with water. We are taking measures to make sure this doesn't happen again, but we need to assess the current deformed column and what needs to be done.
I will try to get some photos for everyone to view.
RE: Water freezing in HSS Column
Myself and my boss, also a structural engineer, have come to the conclusion that the deformation in the column will not affect the intended design function except at the base of the column. (I've been an engineer for almost 7 years, and my boss has been an engineer for over 30 years.) We will be reinforcing the base of the column with gusset plates welded to the column and the baseplate.
Here are some of the reasons:
1. The column has a factored capacity of 1200kN. The factored load on the column is only 400kN. The column is over-designed.
2. I've done some computer modeling of the deformed vs original column. The increased local moments and forces did not increase a significant amount and is still within capacity of the steel.
3. The section modulus would not decrease with the new shape. Technically it would increase, but I don't want to consider this in my analysis.
4. Deformation of the column is approx. 20mm from original shape on all 4 sides and there were no signs of any fractures.
5. My boss says that the steel itself would be strong by way of working the steel from the deformation, but I choose not to consider this in the analysis.
Naturally we will keep an eye on the affected columns to make sure there is no more changes in shape, but the initial water freezing in the column will not happen again. The column is sealed and there are also holes in the bottom that was drilled to drain the water.
Thank you to everyone for your input and please feel free to continue sending opinions. I've enjoyed debating this subject.
RE: Water freezing in HSS Column
Thank you for the update. I believe your decision is appropriate.
RE: Water freezing in HSS Column
BA
RE: Water freezing in HSS Column
Thanks! Always good to hear!!