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Re: 22-1/2 degree masonry bolts[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaoc(--nospam--at)seaoc.org
- Subject: Re: 22-1/2 degree masonry bolts
- From: "Sandy Pringle" <sandyp(--nospam--at)beachnet.com>
- Date: Wed, 29 Jan 1997 21:33:42 -0700
At 11:40 AM 1/29/97 -0800, you wrote: >Does anybody know what is the accepted inclination of 22-1/2 degree epoxy >bolts in unreinforced masonry (upwards, downwards, sideways)? > >It seems like the most common practice is to install them downwards, but >what do you do when the bolts are at the ceiling? > >Thanks in advance, > >Alexander (Sasha) Itsekson >Huntington Design Associates The Inspection Practices Committee has participated in the investigation of the use of epoxy anchors since their beginnings in the early 1980's. There are several reliable manufacturers of these adhesives with ICBOES and City of Los Angeles(COLA) approval. COLA Guideline 3 was developed originally for the quality control of the installation of the URM shear anchors which necessarily encompassed the 22 1/2 degree installation. Guideline 3, first revised in 1986 allowed for the installation of 22 1/2 degree anchors upwards or downwards, not sideways, for either the grouted 2/1/2" cored anchor or the epoxy type. Subsequent investigation required the discontinuance of the grouted anchor installed in an upwards direction due to the unreliability of the installation procedure's quality, but it was found that the adhesive filled screen tube used with the epoxy type system allowed encapsulation of the adhesive in place so that the anchor could be installed before the material ran back out of the hole, in most cases. COLA Guideline 3 also requires Continuous Inspection of the installation of ALL inclined or declined anchors to further tighten the quality control, because under the higher temperatures of summer, for instance, the viscosity is higher and the material does, in fact, run. There are several ways commonly used for resolution of this particular problem, the most significant of which is to wait until early in the day when the ambient and material temperatures are low enough not to be a problem! It doesn't take a Brain Surgeon for some of these solutions, fortunately, but experienced Inspectors have dealt with or have Principals to whom they can turn for difficult situation solution development who may, in fact, be calling you for suggestions or approval. The quality of the installation is the responsibility of the Contractor and steps he must take to ensure the quality of the installation vary from Contractor to Contractor and, as far as we Professional Inspectors are concerned, whatever can be shown to work is OK. Sometimes we can make suggestions, but we must be careful not to take the responsibility for the installation from the Contractor and, in most cases, can only make suggestions. This isn't an arena in which there is a lot of guidance and codes. This does require Inspectors experienced or trained in the vagueries, if you will, of URM Retro-fit to ensure conformance to the spirit of your plan. The COLA Research and ICBOES Evaluation Reports go a long way toward clarifying and delineating each step of the procedures, but then there are those cases...... As far as the testing of 22 1/2 degree anchors is concerned....5% Tension Testing is what was specified when Hilti first came out with the C-20 system and was included in the procedure, but I'm afraid there aren't any failures, and the City of Los Angeles has long since discontinued the insistence of this type of testing although it is still on the books. The testing is a pull on the pre-bent bolt. Since the bend occurs at the face of the wall, the test is really of the quality of the piece of wall within which the anchor lies. Certainly the anchor isn't going to snake out of the hole like a piece of spaghetti if the adhesive is incorrectly mixed; however it would show some movement since the hole is bigger than the anchor itself. The use of the two component cartridge system and the static mixing nozzles go a long way toward ensuring proper mixing, but it still takes an experienced and trained, Certified Inspector to best ensure the installation of your anchors and since the UBC in section 106 requires the Engineer of Record to specify "the names of the individuals or firms performing Special Inspection and the disciplines which they will inspect", you now have the codified opportunity to do just that. Specify the Inspector....... But that's another thread altogether and one, I might add, to which I warm quite promptly. R. Sandy Pringle STRUCTURAL INSPECTION CONSULTANTS Sandy Pringle & Associates (800)598-1970 Fax(310)376-5294 http://www.beachnet.com/~sandyp/index.htm Hermosa Beach & Redondo Beach, CA Don't count the days, make the days count.
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