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Water freezing in HSS Column 1
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msquared48
Structural
I assume that you are talking fresh water here?
Mike McCann
MMC Engineering
Mike McCann
MMC Engineering
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blackmaddog
Structural
- Oct 13, 2008
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If the freezing action didn't split the HSS or permanently deform the shape, I would think it is okay. Prevent the water from getting inside or drain it to prevent future damage. I have seen ice split HSS before so detailing to prevent water intrusion is very important.
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@blackmaddog
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.
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.
JedClampett
Structural
If the column is deformed, you've introduced second order moments in the plates. The calculations will be messy and will have a unknown component (like the loss of deformation in the metal). So it's almost a certainty that the deformed section will have to be removed and replaced. And that is probably done easiest by replacing the 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.
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.
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@JedClampett
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.
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.
(Ok, gonna take a swing at this one.) I think that it would be unwise to assume that you can switch from plane stress to hoop stress when the orginal section deformed from square to circular. At deformation your steel is near yieling, therefore your allowable stresses have changed. I'd replace the column and sleep at night.
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JedClampett
Structural
Actually, my idea of a template was just to check the deformation of the column, but if you could wrap it with a larger column including the damaged area and above and below, that might work. It might be harder than it seems as the bulge will be irregular and there will be uneven gaps.
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.
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.
If the wall of the HSS columns have not actually fractured or separated from the base plates, I would not be as pessimistic about this as some. The area of steel is still there to resist the compressive force, and the section modulus is actually increased slightly for bending. Therefore, the ultimate strength of the member is not reduced.
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.
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.
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@CCB1
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.
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.
Compositepro
Chemical
It is not simply freezing of water that causes damage, but how it freezes. Freezing from the outside toward the center will not cause any damage if the unfrozen water can flow out as the water freezes and expands. The worst case (which commonly occurs) is that the top layer of water freezes first because ice floats and because there is more heat transfer from steel not in contact with water to steel that is in contact with water at the air/water interface. This forms a plug that traps the unfrozen water, which will increase in pressure as it progressively freezes.
Keep the water out, put in drain holes, or fill the column with concrete or Styrofoam.
Keep the water out, put in drain holes, or fill the column with concrete or Styrofoam.
We dealt with a similar situation, with damaged interior HSS columns damaged by forklifts. Repairs ranged from plates welded on (simple clean puncture, no bending or deformation other than very localized), to welding of angles and/or plates or channels (minor bend or partially out of square), encase in concrete to height of 2' above damage (including fill interior) , and also total replacement where damage was to extensive to repair (and risky). You have to use judgement and may require a testing company or steel inspector/engineer specialist who has been around and understands deformation, extent of non-visible damage and is practical about repairs that are
applicable. We were surprised with the damage we saw?!
Play it safe, not a place to try to save.
applicable. We were surprised with the damage we saw?!
Play it safe, not a place to try to save.
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- #17
paddingtongreen
Structural
I'm not sure what damage is done here. the metal has been worked, but then it was worked even more during the forming process. In forming it was squeezed from round to square without losing capacity, now you've tried to make it round again.
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.
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.
Whoa!
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.
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.
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