Increasing shear capacity of metal building column connection to concrete pier 1

[McSEpllc]

Hi All,

In order to increase shear capacity at the connection of a per-engineered metal building column to a concrete pier, the metal building engineer suggested the attached detail. It uses a steel angle that the anchor bolts extend through within the concrete pier. I guess to engage the concrete.

Have any of you used this detail?
What do you think about it?

It seems it offsets the location of shear resistance down into the concrete, and one could argue that induces bending into the anchor bolts. On the other hand the anchor bolts are within the reinforced concrete pier, so can not deform.

Thanks!

 

[McSEpllc]

I am doing hand calculations on the anchor bolt connection of PEMB steel columns to the concrete piers.
There are couple items that are not clear to me.

Looking at ACI 318-14, §17.5.2.2 (page 251), which is attached:

1.) le is defined as the load bearing length of the anchor in shear.
If I have a headed anchor bolt, I assume that le is the distance from top of concrete pier to the nut on the bottom of the anchor bolt - is that correct?

2.) h[sub]ef[/sub]: Does ACI have limits for minimum and maximum lengths on a headed anchor bolt?

3.) §17.5.2.3 gives a potentially larger allowable shear capacity when the headed bolts are continuously welded to the steel attachments.
Does this mean the nut of the headed anchor bolt would be welded to the column base plate (or the nut to washer, and washer to column base plate)?



[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1642041837/tips/ACI_318-14_p251_rmtch5.pdf[/url]

 

[GC_Hopi]

You should get this reference, CSA published a guide called Design of Anchor Reinforcement in Concrete Pedestals. You can find it using the google machine.

le is typically taken as hef
hef is not limited
It does but you should need to go down that path. Just use rebar as the anchor reinforcement.

 

[GC_Hopi]

 

[Spanky7]

ACI 318-14, §17.5.2.2 defines le as

ℓe = hef for anchors with a constant stiffness over the full
length of embedded section, such as headed studs and post-installed
anchors with one tubular shell over full length of
the embedment depth;
ℓe = 2da for torque-controlled expansion anchors with a
distance sleeve separated from expansion sleeve, and ℓe ≤
8da in all cases.

There is no current limit on hef. The old rule of thumb was hef >= 12da and is still a recommended practice in PIP STE05121 Anchor Bolt Design Guide. Process Industry Practices

https://vdocuments.mx/pip-ste05121-anchor-bolt-design-guide-578f221c37ba1.html

I agree with GC_Hopi just use rebar to provide anchor reinforcement. The following references are a goods stating point for understand how perform this type of design.

Widianto, et al. “Design of Anchor Reinforcement in Concrete Pedestals.” CSA Today, III, no. 12.

https://www.sefindia.org/forum/file...nforcement_a_petrolium_project_papers_199.pdf

Widianto, et al. “Design of Anchor Reinforcement in Concrete Pedestals.” Structures Congress 2010, 2010, doi:10.1061/41130(369)225.

https://ascelibrary.org/doi/abs/10.1061/41130(369)225

 

[McSEpllc]

Thank you GC_Hopi for the highlights on the section - I missed that before, and Spanky7 for the info and links.