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Short anchor bolt projection[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: "SeaInt Listserver (E-mail)" <seaint(--nospam--at)seaint.org>, "'Charlie Carter'" <carter(--nospam--at)aiscmail.com>
- Subject: Short anchor bolt projection
- From: "Sherman, William" <ShermanWC(--nospam--at)cdm.com>
- Date: Mon, 9 Oct 2000 11:56:16 -0400
I have a situation in which the projection of an anchor bolt is about 3/16" less than required for nonshrink grout, base plate thickness, washer and nut (based on field measurements of actual anchor bolt projection and base plate thickness). We are using 1-inch diameter galvanized A307 anchor bolts in 1-1/8-inch diameter holes. There is no calculated uplift on the anchor bolts but they are required for shear. I am considering three options: 1) delete the washer; 2) use "standard hex head nuts" in lieu of "heavy hex nuts"; 3) allow the anchor bolt to stop short of the top of the nut, using a heavy hex nut. As I understand the purpose of a washer, it is intended to be used under the part turned in tightening of high strength bolted connections to prevent galling of the surface, and it helps distribute loads where oversized holes are used in base plates. While an anchor bolt needs to be tightened down, it does not need to be pretensioned to the level of an A325 bolt, so galling does not seem to be as big of a problem here. The hole diameter in a washer for a 1-inch bolt is 1-1/8" diameter, the same as in my base plate; so provided that the base plate holes are not enlarged in the field, the washer should not be necessary to distribute load. On this basis, I don't see a need for the washer - any other thoughts on why a washer might be necessary? Elimination of the washer would allow the bolt to extend flush with the top of the heavy hex nut. Although heavy hex nuts are provided with the anchor bolts, according to Table X1.1 attached to ASTM A563, standard hex nuts can be used with A307 bolts if of the appropriate grade. Unfortunately, this would only eliminate 1/8" vs the 3/16" I need. The base plate is 1/8" thicker than the what was specified, so I could grind down the base plate by 1/16". Similarly, if a heavy hex nut was provided but a standard hex nut would suffice, would it be acceptable to allow the bolt to project into the heavy hex nut only the distance as required for the height of a standard hex nut, if of the same grade material? Any thoughts on these solutions would be appreciated. William C. Sherman Camp Dresser & McKee, Inc. Denver, CO Phone: 303-298-1311 Fax: 303-293-8236 email: shermanwc(--nospam--at)cdm.com
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