How would I go about assessing the anchors in profis where I have the base plate sitting on top of a 100mm tall concrete plinth with about 20mm levelling grout? Would I use the standoff option 'stand-off with grouting' and input the distance as 120mm?
Hi Homan,
Thank you for contacting Hilti.
The answer to your question would depend on multiple factors. The first (and one of the most important ones in my opinion) is whether the height of the concrete plinth of 100mm is considered to be a part of the anchor's embedment depth or not. I would personally suggest designing for the worst case scenario and design the capacities using the main concrete below only. However, please keep in mind that this would need to be done based on your judgement as the plinth and the concrete member are technically 2 separate concrete members and they would fail under loads in different manners.
The use of a chemical anchor is advised here due to its working principle. Chemical anchors have a uniform load distribution along the entire embedment depth, which would take advantage of both the main concrete and the plinth when working under loads (this would help in case you choose to take the plinth into consideration when designing for the embedment depth of the anchor). If you choose to go with this option, please assess the plinth's dimensions for the minimum spacing and edge distances associated with the anchor in use.
Lastly, if you choose to consider the plinth's height in the stand-off's total height, this would create a high steel failure utilization as it would increase the bending moment value applied at the steel at the point where it meets the concrete's surface (120mm away from your applied load), which would make the design more complicated to get it to work.
I hope the different ideas above help you with your design judgement for this application. Please don't hesitate to reach out to our customer service team at 131 292 if you have further questions and they would connect you to one of our engineering members to help you with any questions you may have.
Kind regards,
Ask Hilti Team.