Anchor Tensile Reinforcement Position 2

[Jerehmy]

I have a steel portal frame columns fastened to reinforced concrete piers.

In ACI 318-11, figure RD.5.2.9 show the anchor tensile reinforcement on the outside of the anchor bolts. I have a large base plate on the pier and there isn't much room outside the anchors for additional reinforcement. Can the anchor tensile reinforcement be placed underneath the plate?


Better yet, can I just use the flexural reinforcement at the edges of the pier if it's close enough to the anchor bolts (<0.5 h_ef)? The stress in the flexural reinforcement will be less than 0.1Fy where it would be used as anchor reinforcement.

 

[KootK]

I vote yes on both counts so long as the proper lever arm / effective depth is used for the rebar. I believe that utilizing the flexural rebar as you've suggested is, in fact, the conventional way to go about this. In many cases, you need the tension to make its way out to those bars anyhow.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Jerehmy]

The figure also shows the tensile reinforcement placed like stirrups in a U. this seems like a pain in the butt to install flexural reinforcement that way, especially since this pier is 9.5ft high. Can I not install the flexural reinforcement with 90 or 180 deg hooks at the top and just ensure it is properly developed within the breakout cone?

 

[KootK]

Can I not install the flexural reinforcement with 90 or 180 deg hooks at the top and just ensure it is properly developed within the breakout cone?

I would say so. I don't even do a 90 degree hook most times as I don't care for the congestion that often results. And, when there is congestion, I suspect that they just cut the hooks off half the time anyhow.

I think that part of the difficulty is that, although we use it for big stuff, the ACI anchorage provisions were really developed with small scale stuff in mind (embeds etc). If you don't already have the Widianto paper on this, I highly recommend it.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Jerehmy]

No I haven't, thanks!

 

[KootK]

You're most welcome Jerehmy. Sounds like your intuition is steering you in the right direction.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.