Williams Hollow Core/Grouted Anchors

[LSPSCAT]

I am looking for any additional design aides/references for Williams Hollow Core Rock Anchors. The application is specified by an owner/consulting engineer to be used in existing concrete. Williams seems to refer to ACI 349 and stay away from 318 Appendix D.

Specifically, for a grouted anchor there is typically a bonded length and free stress length...if the contractor plans on grouting initially full depth where would you assume the shear cone development begins, if grouted full depth would you assume it begins at the embeddeded tip of the anchor? Also, the information from Williams is clear for tensile loadings, however, besides the steel strength, how do you determine the shear strength? Some old PCI design guides from 1979 limit the shear allowable for concrete failure based on the breakout cone.

 

[LSPSCAT]

Also, the loads for this application are relatively small for around 15000 lbs in tension and around 5000 lbs / anchor in shear. We are looking to keep tht embedment to a minimum.

 

[DaveAtkins]

Are you simply embedding this in rock, or are you grouting around the anchor along its length as well (in the soil)?

ACI really doesn't apply here--your geotechnical engineer or Williams should be able to answer your questions.

DaveAtkins

 

[LSPSCAT]

It is being embedded into existing (OLD) concrete.

 

[CTW]

They don't use ACI 318 because it doesn't apply to grouted anchors. I believe this is stated in the scope section of ACI 318 App D.

Why would the consulting engineer specify a rock anchor for concrete? Any chance of submitting a more reasonable anchoring system such as epoxy?

 

[LSPSCAT]

Epoxy anchors are not allowed. I realize ACI 318 does not apply to grouted anchors.