ICC-ES AC Interim Criteria for Inspection and Verification of Concrete and Reinforced and Unreinforced Masonry Strengthening Using Fiber-reinforced. Accordance with. ICC-ES AC ADVANTAGES. DESCRIPTION/SUGGESTED SPECIFICATIONS*. The % epoxy resin and hardener are completely mixed. As such, Hilti maintains ICC-ES evaluation reports for adhesive anchors in concrete according to AC and in masonry according to AC I hope I have.
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Formal concrete anchorage design provisions first appeared in ACI as Appendix Av308, with applications limited to cast-in-place anchors and post-installed mechanical expansion anchors.
In 12 years, we have codified anchorage design procedures and developed anchor qualification standards that have greatly raised the reliability bar for anchors used in practical design conditions. So, what is the state of the anchoring industry and where do the codes go from here?
AC – ICC Evaluation Service, LLC (ICC-ES)
The new structural building code ACI will be re-organized based on member type. Appendix D will now formally be placed in the body of the Code as Chapter But unlike other chapters in the re-organized Code, Chapter 17 essentially remained an untouched clone of Appendix D.
This was a conscientious decision by the Code Committee at the beginning of the reorganization work, because: The next code cycle will contemplate further additions and layout reorganization. Adhesive anchors were incorporated into ACI under the premise that the existing design models would be minimally affected. Adhesive anchor design provisions for tension were the only provisions supplemented, necessitating new checks for concrete bond stress.
Adhesive anchors loaded in shear behave similar to other post-installed and cast-in-place anchors, and, hence, existing design models and procedures could be used. For post-installed mechanical anchors, anchors must be qualified to the criterion in the ACI Based partially on the Boston Big Dig tunnel accident, the adhesive anchor installer must be certified to install anchors in certain orientations and under certain load conditions.
This requirement is recognition by the ACI Code committee that adhesive anchor installation ac08 some oversight qualifications to achieve satisfactory installations, consistent with the written design requirements and anchor manufacturer installation instructions. aac308
The success, or failures, of adhesive anchors are highly dependent on the installer and the procedures employed to install the anchor. Certification was deemed an important ucc-es of adhesive anchor usage, on par with certified welders for welding key structural steel connections. In addition to installer certification, inspection is an important requirement required in ACI The ACI Code provisions are not mandatory unless adopted by the local building code for the given jurisdiction. Reference should be made icc-rs a paper by Hoermann-Gast for additional information.
There are a wide variety of post-installed concrete anchors, and the newest post-installed anchor is the screw anchor. In reality, screw anchors have been around since the early s.
They are intended to carry direct tension, direct shear, or combinations of tension and shear loadings.
Although the design procedure for screw anchors has not been codified, they are gaining acceptance in building practice as a reliable fastening element Olsen, et.
To provide the mechanical interlock to the concrete, the ivc-es anchor cuts a thread into the concrete during the installation process. This makes the use of screw anchors a single-use item; removing and reusing the screw anchor in the drilled hole is not advised because the cutting threads on the screw are worn and getting the screw threads into the original cut threads in the concrete is difficult.
In Figure 1, the undercutting of the threads in the concrete is illustrated. The creation of the threads in the concrete gives the screw anchor some advantage in cracked concrete where a small-narrow crack intersecting the threads icc-ds only a minor reduction on tension capacity.
Undercutting of screw threads in concrete from Olsen, et.
AC308 – Post-installed Adhesive Anchors in Concrete Elements
In the next Code cycle, screw anchors will be studied for inclusion. Research testing of screw anchors has shown that failure can occur in tension via three modes: Pullout failures look very much like bond failures for adhesively bonded anchors.
Pullout failures also occur for screw anchors only when they are deeply embedded. Deep embedments are often difficult to achieve because the friction of cutting a thread can exceed the torsional capacity of the screw shank and fail the steel in torsion. AC also outlines the qualification tests required for screw anchors. Neal may be reached at nsanderson sgh. Aug, By Neal S. In ArticlesInSights Comments 0. The Present State of the Industry Formal concrete anchorage design provisions first appeared in ACI as Appendix D, with applications limited to cast-in-place anchors and post-installed mechanical expansion anchors.
STRUCTURE magazine | Post-Installed Anchors
Design Provisions Adhesive anchors were incorporated into ACI under the premise that the existing design models would be minimally affected.
Qualification For post-installed mechanical anchors, icces must be qualified to the criterion in the ACI Certification Based partially on the Boston Big Dig tunnel accident, the adhesive anchor installer must be certified to install anchors in certain orientations and under certain load conditions.
As of 15 Januarythe following actions were taken: This includes the design provisions for bond strength and concrete breakout.
As of 15 Januarythe following will be required: Screw Anchors There are a wide variety of post-installed concrete anchors, and the newest post-installed anchor is the screw anchor. Leave a Comment Click here to cancel reply.
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