I wish. There're some things that nobody wants to write down for fear of attracting unwanted liability. This probably falls into that category. Your best bet will likely be case study articles and research papers. I know that I've seen something from Leo Panian dealing with jacketed coupling beams in seismic shear walls. Of course, that's a pretty specific application.
A text on general composite design may be useful. I have an excellent one by Viest called Composite Construction Design for Buildings.
What's your particular application? Moment capacity? Shear capacity? Seismic confinement?
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
EYFS:
The primary reason for jacketing is to confine the concrete during a high stress crushing failure occurrence, isn’t it? If so, the steel jacket will work well on a round column, where the expanding conc. volume puts the steel jacket in hoop tension, and the conc. is confined. This method will not work very well, for that purpose, on square or rectangular members, because the conc. volume change will cause plate bending in the steel jacket, not hoop tension, thus much more conc. movement can occur. I would expect the steel jacket to add some shear cap’y. to the conc. member if it is well attached to the conc. I’d see what I could find on this subject at ACI and CRSI, and might expect to find a few tech. papers on the subject. I’m not so sure I’d expect to find a handbook on the subject, and probably not much in most conc. design textbooks either. This is a fairly specialized subject and reinforcing means.
Thank you for the reply Kookt,dhengr.
I have an old building and the owner needs to build a second floor. The column are small to handle a second floor so im tring to find the best solution for this case. So i was thinking of jacketing but i did't found any resource to start with.
FRP might be an attractive alternative. You could also do your jacketing in concrete if there's space. No matter which way you go, it might be worth checking out an FRP text. It will have examples dealing with external reinforcement. Similar principles will apply no matter what the material.
Two things to keep in mind:
1) Fireproofing the finished product.
2) Some stresses will be locked in pre-reinforcing.
How close is your column to its squash load?
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
I prefer not to go to FRP due to several resons , fire , cost, application...
The column is very old ,built with a "foreman " site experience ..so i prefer to consider it very close to squash load.
I will check the FRP text maybe i can find somthing helpfull.
Maybe i can model a column and transfer the forces to a wall surrounding it..
Ah... I see. You could bolt channels to opposing sides of the column, stitch the channels together, and then disregard the concrete column altogether. You'd still need to deal with punching shear and getting the loads in and out of the channels of course. I'm assuming that this is a pretty small column.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
Its 40x20 with 6d12 mm bars ( smooth ). Consider the concere 15 Mpa
Can't we just transfer the load to a wall( its will act as jacket) i think it will be more conservative..
Steel chanels is good idea but not cost efficent..am I right?
steel jacketing has been done extensively by Caltrans on bridges in California for seismic retrofit for the last 20 years. none of these were circular columns, although many of the finished jackets are either circular or elliptical. they are all steel with grout infill. You might find some sort of published papers regarding this.
That's a pretty big column for a one story building. Are you sure that it needs reinforcing? I don't understand your wall idea. Is that just the concrete jacket idea that I mentioned above? I would think that steel reinforcement would be cheapest but that would depend on a lot of variables that I don't have knowledge of.
You might want to post some sketches. You often get better advice that way.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
The actual column is very old with very low strenth concrete plus there is no data about the steel strength ...there was no engineer supervised or designed it..so i cannot rely on it as actual column...
Thank you kookt for your replies
Have you checked the foundation capacity? Are they able to take anticipated load of proposed second floor, without any problem? In case they are NOT, you would need to strengthen the foundations first.
Load carrying capacity of columns may be increased by several methods. For example, concrete or steel jacketing and FRP wraps. Following books might help you in this connection:
1. Concrete Structures - Protection, Repair and Rehabilitation by Dodge Woodson
2. Retrofitting Design of Building Structures by Xilin Lu
3. Strengthening and rehabilitation of civil infrastructure using FRP composites by Hollaway and Teng
4. Composites for Construction_Structural Des with FRP Materials by Lawrence Bank
Thanks for the sketch EYFS. I was hoping for a mini-framing plan and cross section however. There's only so much that we can do to help without a better understanding of the situation. Frankly, for a one/two story building, I'd almost think that an unreinforced 20"x40" 15 MPa column would work. Is the column supporting long span framing or a transfer girder? Is it part of a moment frame?
I wouldn't look at the concrete jacketing as walls. I'd consider it to be a square column. Whether that column is solid or a doughnut will depend on what kind of connectivity you intend to establish between the new and existing concrete.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
Thank you PSEPK for the resouces.
KOOTK,
I was tring to find a way to model it on ROBOT. Sorry I don't have any framing plan with me now. But I got your idea. Thank you for your help.
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