Is the actual Nominal & Effective embedment before or after tightening the nut? Also, is the difference between Effective and Nominal embedment always the same? For example, after tightening the nut, the location of the loading mechanism is always the same distance from the bottom of the anchor?
I am assuming when QA verifies anchor installation, the only check is using the nominal embedment with the length of the anchor and amount sticking out of the concrete and then calculating the nominal embedment, and if the nominal embedment is met, then the effective embedment is also meet.
Hi Dave,
- Nominal embedment is more easily and readily measured onsite, as it is measured from the bottom of the anchor to the top of the base material.
- Effective embedment conveys where the loading mechanism for the anchor engages the base material and is used throughout anchor calculations. It the measurement from the bottom of the expanded wedges to the top of the base material.
When the installation torque is applied, the anchor is drawn up into its wedges which should then be acting at effective embedment. The difference between the effective and nominal embedment is not always the same.
Additionally, see this previous Ask Hilti response, found at the bottom of the page here; it provides some great insight and technical knowledge regarding nominal and effective embedment of expansion anchors if you wish to know more.
Best Regards,
Emily