ACI 318 App D - side blowout
ACI 318 App D - side blowout
(OP)
Working on a project where we have steel embed plates with headed studs welded to the plates. The embed plates are installed in concrete columns. The capacity of the embed plates are controlled by side blowout because the headed studs are too close to the sides of the column. ACI 318 is vague regarding the use of supplementary reinforcing. My question is this: without supplementary reinforcing, I need to increase the column width so side blowout is not an issue or add supplmentary reinforcing through the shear cone of each stud near the edge. The architect says no-go on the column size increase. So, if I add reinforcing through the shear cone, it appears to me that side blowout can be ignored. Is that how anyone else interprets the use of supplementary reinforcing? I have vertical bars at each corner of the column and each face. Those bars pass through the side blowout zone. I will add more column ties in the area of the embed plate. Just not certain that is enough to satisfy the side blowout issue and get a larger capacity for the embed plates.





RE: ACI 318 App D - side blowout
RE: ACI 318 App D - side blowout
RE: ACI 318 App D - side blowout
Some useful references that we found:
1) ACI 349.2R-07: Guide to Concrete Capacity Design (CCD) Method - Embedment Design Examples
2)Eligehausen, Mallee, Silva, "Anchorage in Concrete Construction" Published by Ernst & Sohn in 2006
3) Comite Euro-International Du beton; "Design of Fastenings in Concrete - Design guide". Published by Thomas Telford Services 1997.... Probably not as useful for US engineers as the others.
I'm not sure why, but it seem like the Europeans have really lead the way with the anchorage research.... Thankfully, all the books / guides I've listed above are published in English.
I hope that helps. :)
RE: ACI 318 App D - side blowout
RE: ACI 318 App D - side blowout
318-08 App D commentary says that "An explicit design of supplementary reinforcement is not required. However, the arrangement of supplementary reinforcement should generally conform to that of anchor reinforcement shown in Fig. RD.5.2.9 and RD.6.2.9(b)." These figures show typical reinforcing methods to increase resistance to side-face failure.
John Turner CSP PE
CRSI Greater Southwestern Regional Manager
RE: ACI 318 App D - side blowout
RE: ACI 318 App D - side blowout
A single leg tie between the face bars in the column should work (depending on needed strength.) Using hairpins around the studs, [per RD.6.2.9(a) or (b)] tying them back to the remaining concrete mass is another way to go.
RE: ACI 318 App D - side blowout
RE: ACI 318 App D - side blowout
Be sure to spec A706 rebar and low hydrogen E90XX electrodes. The E90XX electrodes allow for smaller fillet welds from bar to plate to develop the bar.
PCI has tables giving the fillet weld size needed to develop various size bars for different electrodes.
RE: ACI 318 App D - side blowout
RE: ACI 318 App D - side blowout
"Back in the day", beefier connections and members allowed more room for error by being stronger than required. Less precise control of material properties frequently meant errors to the high side in an attempt to avoid weakness.
Designing with precise tools means less room for error, so errors will start showing up as failures sooner or later.