Column Concrete Jacketing longitudinal rebar construction scheme

Use the following if you could, much simpler

If seismic retrofitting, use OPTION -2..

There are case studies, design documents and some of the free ..Write RETROFIT CONCRETE COLUMN JACKET ..One of the valuable outcomes ;












Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

To answer this question well, we'd need to know what specific load actions are necessitating the reinforcement. If it were column buckling alone, you might get away without taking the reinforcing into the joint at all. On the other hand, if you need raw cross sectional strength gain through the joint that would rely on the reinforcing, then the reinforcing probably needs to pass through and be lapped for compression or tension as appropriate (most likely the case given your description). Lastly, if you need the reinforcing steel to transfer additional moments into the beams, this may not be possible/practical at all given the available detailing options.

The place to start here, I think, is by running some numbers on the joint itself. Most codes will allow the compression in the slab at the joint to be increased somewhat to account for the beneficial effects of confinement. This kind of thing can sometimes allow you to relax your requirements.

One thing that makes me a bit nervous with the pass through schemes is that it often requires coring through the all important slab top steel right at the column. Then, with that potentially missing, your slab punching shear capacity at that level can become problematic.

adn26 said:

Use the following if you could, much simpler

Click to expand...

I disagree. I might give that scheme some credit for column buckling enhancement but I doubt that it would be effective for transferring any meaningful axial force across the horizontal framing (beam/slab). Consider:

1) Owing to fastener slip/slop, you'd pretty much have to fail the slab/beam in shear before you'd really engage the angles axially.

2) Even if you could engage the angles, your axial transfer to them would be limited to the paltry capacity of the four bolts at the top of the column which would probably have to fail as concrete anchors (limited edge distance) before transferring the load in steel to steel bolt shear. This is the only viable path from the angle rings at the top and bottom into the vertical angles. At the least, those ought to be welded joints.

To the extent that the scheme might work for some select purposes, I also wouldn't bother with the battens. The bolts should restrain the individual angles adequately for buckling every which way and, without the battens being trussed in any way, they won't do much to promote stiffness of the four angle assembly.

@adn26: is your reinforcement detail perhaps an attempt at augmentation via confinement? The hoop spacing looks big for that but it would explain the general form of it.

@ kootk
you are correct, this was only one part of solution, there are additional similar schematic for beam-slab strengthening
here the welding between vertical & horizontal parts will be key-strength not the shear-slip bolts
confinement as you indicated is the basic-mechanism axial capacity increasing for the column
did provide this solution to replace concrete section-enlargement
also did this layout with cross-bracing plates in one of old building
..
Note; during strengthening I notice that labors forget entirely about building lateral support, i.e. they remove entire brick-walls between columns without providing any temporary lateral support to vertical members