eccentrucally loaded bolt group in concrete

[RWW0002]

Due to a some interesting existing conditions, I have been asked to attach a beam to an existing pilaster in a way that results in torsion on the connection. We will be drilling and epoxying anchors into the pilaster and they will be loaded with eccentricity in the plane of the connection. I have analyzed this condition using the Elastc method for eccentrically loaded bolt groups per AISC. My question is whether the brittle nature of concrete violates the assumptions of this method. In other words, will the worst-case bolts take all the load and fail (bond failure or concrete bearing) before the other bolts see the load due to insufficient deformations. Any thoughts??

 

[connectegr]

I think the Hilti Profis program will design this eccentric connection.

http://www.FerrellEngineering.com

 

[RWW0002]

Thaks Connect. I have never used Profis, but I will check it out.

 

[RWW0002]

Profis seems to assume a force distribution similar to that of the Elastic Method mentioned preiously.

As I was checking my calculations though, I noted that Profis uses a very low Spacing Adjustment factor (fA) compared to values I have used in the past. For HY 150 epoxy w/ 5/8" Dia HAS, the fA value used by Profis is 0.343 for a 3" anchor spacing. From my understanding of the HILTI manual, fA should never be less than 0.70 for HY 150 and comes to around 0.73 for this condition. I am not very familiar with the program and I may be missing some input, but something does not seem correct here. Has anyone had much experience with design using Profis?

 

[UcfSE]

I don't see any issue using the elastic method in your case.

 

[jdgengineer]

I have done the elastic method as you are describing in the past. I dont see a problem with it either. One thing to note: I'm assuming you aren't in a seismic area a HY150 is not cracked concrete approved.

 

[RWW0002]

Thanks for the responses.

The seismic category is borderline (SDC B with Site Class C, SDC C with Site Class D), so I am fighting on whether to go with HY150 or a seismic approved epoxy (RE500 SD).

The ironic thing is that the existing structure that we are working on (only adding RTU's) is all un-reinforced masonry built in the mid 80's. Not exactly seismic friendly...

 

[UcfSE]

Hilti make HIT-HY 150 MAX-SD, which is cracked concrete approved.

ESR-3013