Concrete embedded bolt pullout strength
Concrete embedded bolt pullout strength
(OP)
For years I have used a procedure in CONCRETE INTERNATIONAL dated July 1981 titled “Guide to the Design of Anchor Bolts and Other Steel Embedments” which outlines how to calculate the concrete pullout strength of embedded bolts in concrete. The procedure basically uses the tension strength of the concrete applied to the surface area of a 45 degree cone that has a height measured from the top of the embedded bolt head to the top of the concrete. This gives a formula based on the height squared. The ACI code has recently added an Appendix D which goes into detail regarding bolts embedded in concrete. The basic pullout value for a single bolt is stated in formula (D-7). The constants in the formulas for the different methods are very similar except in the first, the height is squared and in the second the height is raised to the power of 1.5. Unless I am missing something, the resultant pullout strength is considerably different, especially as the embedment depth becomes larger. For this reason, many of the standard foundations I have designed will no longer pass the requirements of the latest ACI 318 code. Does anyone have any comments or suggestions?






RE: Concrete embedded bolt pullout strength
RE: Concrete embedded bolt pullout strength
A very good reference is Chapter 34 Anchoring to Concrete in the PCA's publication "Notes on ACI 318-02 Building Code Requirements for Structural Concrete". It is well worth the price.
RE: Concrete embedded bolt pullout strength
RE: Concrete embedded bolt pullout strength
RE: Concrete embedded bolt pullout strength
I don't know if you need be overly concerned about your previous projects. The anchorage analyses and the requirements spelled out in Appendix D are for plain concrete. Most of my foundations, especially those with piers, have confining reinforcing that penetrates the shear cone and adds to the pull-out strength of longer anchors.
A very good reference for this analysis (which is allowed per ACI 318, section D.4.2.1) is Structure Magazine, July 2004, in an article entitled "Alternatives to ACI 318-02, Appendix D - "Anchoring to Concrete"".
RE: Concrete embedded bolt pullout strength
Does anyone know of a software program which calculates pullout and shear based on ACI318-02 App D??? I really hate to spend the time writing an Excel spreadsheet if I can buy a simple utility.
Thanks
RE: Concrete embedded bolt pullout strength
Thanks for the reminder about this magazine. I had forgotten that it existed as I am in a specialized area of structural engineering. Interestingly I could not find how to subscribe to this magazine at the website. I assume it comes with a membership to the organization but have sent an email for the information regarding the subscription.
RE: Concrete embedded bolt pullout strength
RE: Concrete embedded bolt pullout strength
The article is deinitely in July 2004. It is actually under the column heading "from experience", on pp 39 and 40.
Structure is available as a specialty magazine from ASCE.
RE: Concrete embedded bolt pullout strength
Thanks