Posted by Stevenalmost 2 years ago
Embedment depth of the chemical anchor
Hi,
Could you please explain why a 79mm embedment depth has lower utilization than a 110mm embedment depth? All design parameters are the same, only the embedment depths are different. I merged two design outputs with different embedment depths into one PDF. Could you please review the attachment?
Regards,
Steven
1 Reply
Posted by Mohammed Hamdounaalmost 2 years ago
Hi Steven, Thank you for contacting Hilti.The reason behind the higher utilization ratio for the deeper embedment design case is the disturbance of the projected concrete cone around each anchor, which has a circle diameter of 3 x hef. The spacing between anchors (100mm, 220mm, & 100mm) and the edge distances of 125mm in each Y direction haven't changed between both designs, but you do end up with a larger disturbed concrete cone with deeper embedment depths, which affects your concrete related failure modes. (I've uploaded an image that explains the influence of anchor spacing, edge distance, and embedment depth on the projected concrete cone for your reference). Mathematically, this is represented by the ratio of the projected concrete area of the actual system to the area of a single anchor without edge and spacing effect, which reference EN 1992-4 Eq. (7.13) for the Combined pullout-concrete cone failure calculations shown on pages 4 & 16 of the attached design reports file, and EN 1992-4 Eq. (7.1) on pages 5 & 17.The difference in embedment depths also affect some reduction factors that are related to the embedment depth of the anchors, which also contributed to the utilization ratios for each design case. I've marked the pages mentioned above to highlight those differences for your reference. I hope this helps with answering your question. Please don't hesitate to reach out should you have any further questions or need further clarification. Kind regards, Ask Hilti Team.
