corner r/f in concrete wall
corner r/f in concrete wall
(OP)
Which of the two (A or B) is the correct way to detail the interior horizontal bars of a concrete corner/ intersection? Assume that the walls are exposed to lateral on both sides.
I've uploaded a pdf -- CORNER_RF.pdf
Thanks
I've uploaded a pdf -- CORNER_RF.pdf
Thanks






RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
DaveAtkins
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
bigmig-
I'm not seeing how tension in the diagonal blows out the interior corner. It's force is perpendicular to the corner.
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
"Nilsson and Losberg have shown experimentally that a joint reinforced as shown in Fig 18-41b (with diagonal bar) will develop the needed moment capacity wihtout excessive deformations". (MacGregor). Graphically, it is shown as having 4 times greater joint efficiency than joints without the diagonal bars and only 90 degree hooks.
RE: corner r/f in concrete wall
Thanks for the truss analogy. I had never thought of it that way.
RE: corner r/f in concrete wall
And thanks to you for attaching the detail. Exactly what I was trying to describe, except I think some of the Europeans use hairpins which are a semicircle at the ends rather than two 90 degree bends. The research I have seen suggests that 80% efficiency can be achieved with this joint, and with the addition of stirrups and diagonal ties, 100% is possible in critical areas. With the details given in the OP, the research says that the joints are only 10 to 30% efficient.
Yes, Nilsson et al is the source. For those in Australia, the information is addressed in Warner, Rangan et al.
RE: corner r/f in concrete wall
I would definitely lean to "A" though to avoid possible congestion from the vertical steel placement at the corner considering lap aplices. I can visualize four vertical bars there as normal reinforcing.
Mike McCann
MMC Engineering
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
While I am not an expert, I do undertand the mechanism involves several problems, not least of which is the fact that as you column rotates away from your beam, your hooks can punch out. Also, the compression forces involved serve to further confine and strengthen your hooks in B, while successfully confining A is very difficult since sliding full hoop stirrups over becomes terribly difficult with out-of-beam column joint projecting bars involved.
I have never used diagonal bars and am not certain of their potential effects in an earthquake. Normally the rule is to make your system simple and straight-forward in order to ensure it is easily predictable and critical shear forces can be addressed directly. Bringing the diagonal accross may give rise to an undesirable (and potentially stiffer?) load path, leading to early concrete loss and a reduced strength.
I would be very keen to hear other people's opinions regarding the details in seismic zones.
Regards,
YS
B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...
RE: corner r/f in concrete wall
I was responding to Mike, who compared Type "A" to the hairpin detail. If I understood Mike correctly, he said that there would be four stacks of rebar at some locations using the hairpin detail. I only see three stacks (at the diagonal), same as detail "A". Overall, Type "A" and "B" both seem to have busier reinforcing in the corner than the hairpin style.
RE: corner r/f in concrete wall
RE: corner r/f in concrete wall
I can see your point in seismic detailing. Although I have a lot of years experience, little of it is in seismic applications. But regardless of the corner bar, I would think hairpins would be preferable to end hooks or cogs in any form. Remember, we are talking about walls, not column to beam joints.
RE: corner r/f in concrete wall
*sigh* Must be Sunday; My appologies all!
Cheers,
YS
B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...
RE: corner r/f in concrete wall