This section specifically wants the concrete where the studs are used to be tested to prove that it meets the stud manufacturer’s requirements. Concrete strength depends on its continuous cure time duration under proper conditions from the moment it was mixed with water. In practical terms this means curing while saturated. Strength gain stops forever once it dries. The concrete parts that dry first will have lower strength. This is why concrete outside edge corners often break off and why surfaces tend to spall. These parts tend to be low strength due to less favorable curing conditions.
Depending on the situation, the concrete surface where the stud is driven could easily be the lowest strength portion of that concrete member. This AHJ is prudently asking for proof the studs are going to function as necessary. This means proving the concrete strength at the stud site, not every site, but at representative sites. You can do that by testing the concrete with a nondestructive concrete strength testing method known as the “Swiss Hammer Method” performed at a number of locations to constitute a reasonable test. The test involves a tool that measures how a small pin bounces off the concrete. Your local concrete testing company should have the testing tool, a trained technician and professional staff to create the necessary test report. If the concrete members were manufactured offsite, i.e. precast, then that manufacturer should have created the members under controlled conditions. Ask for signed certification from that manufacturer regarding the concrete strength necessary for power driven stud applications. The AHJ might accept that. Allan Seidel St. Louis, MO > On Aug 16, 2018, at 7:57 AM, Pete Schwab <[email protected]> wrote: > > Forum > We have a project where the AHJ has cited us on this code section. We are > using an engineered hanger in accordance with 9.1.1.2 so I don’t feel that > this code section even applies but that is another story for another thread. > I am trying to figure out what this section is actually stating. Does this > section require that the concrete be tested to prove that it is IE: 3000 PSI > concrete? Or is this section requiring that pull out tests of the powder > driven stud be conducted and that the stud is capable of a 750 LB load as > opposed to 5 times the weight of water filled piping plus 250 PSI. The size > of the hangers are ¾” to 2” and the piping is CPVC. > Thanks in advance for any insight. > Pete > > > > 9.1.3.9.3* Representative samples of concrete into which studs > are to be driven shall be tested to determine that the studs will > hold a minimum load of 750 lb (341 kg) for 2 in. (50 mm) or > smaller pipe; 1000 lb (454 kg) for 21⁄2 in., 3 in., or 31⁄2 in. > (65 mm, 80 mm, or 90 mm) pipe; and 1200 lb (545 kg) for > 4 in. or 5 in. (100 mm or 125 mm) pipe. > > A.9.1.3.9.3 The ability of concrete to hold the studs varies > widely according to type of aggregate, quality of concrete, and > proper installation. > > > > Peter Schwab > VP of Purchasing and Engineering technologies > > Wayne Automatic Fire Sprinklers Inc. > 222 Capitol Court > Ocoee, Fl 34761 > > Mobile: (407) 468-8248 > Direct: (407) 877-5570 > Fax: (407) 656-8026 > > www.waynefire.com <http://www.waynefire.com/> > > <image002.jpg> > > <image004.png> > > I sleep in a sprinklered home, do you? > _______________________________________________ > Sprinklerforum mailing list > [email protected] > <mailto:[email protected]> > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org > <http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org>
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