aisc washer requirements

Plate washers on base plates Structural engineering general

19 04 2011 nbsp 0183 32 Multiple stacked washers that add up to a thickness of 5 16 quot do not meet the requirement The washer must be structural grade steel but does not need to be hardened A 3 8 quot thick plate washer and a regular F436 washer can be used instead The plate washer doesn t need to be hardenedThis washer is a common mass produced washer typically used with structural bolts and high strength bolts of many different specifications Unlike the general purpose and low grade F844 washer the F436 washer is heat treated to a required hardness range and is designed for mechanical and structural use The dimensions below show the standard dimensions for stock Washer Requirements 6 10 1 When are beveled washers required To assure proper bolt performance it is required in the RCSC Specification Section 6 1 1 that the surfaces against which the head and nut bear have a slope not greater than 1 20 with respect to the plane normal to the bolt axis 29 10 2019 nbsp 0183 32 In Table 14 2 of the 15th edition of the AISC steel construction manual there is a footnote that standard ASTM F844 washers may be used if hole clearances are limited to 5 16 quot for rods up to 1 quot 216 1 2 quot for rods up to 2 quot 216 and 1 quot for rods over 2 quot 216 The dimensions you gave 1 3 4 quot rod with 2 1 8 quot 216 hole meet these criteria so a standard washer could be used rather What about Washers Washer requirements are covered in section 2 5 of the rCsC Specification a free download at www bolt council org A few highlights AstM F436 flat and beveled washers are specifi cally addressed A reference to t able 6 1 includes structural grade plate washers note that lock washers are not specifically

steelwise AISC

Washer Requirements 6 10 1 When are beveled washers required To assure proper bolt performance it is required in the RCSC Specification Section 6 1 1 that the surfaces against which the head and nut bear have a slope not greater than 1 20 with respect to the plane normal to the bolt axis 02 10 2014 nbsp 0183 32 The RCSC rule and by extension the AISC rule is that the plate washer must cover the slot regardless of thickness RCSC Specification Section 6 1 2 Slotted Hole when a slotted hole occurs in an outer ply an ASTM F436 washer or 5 16 in thick common plate washer shall be used as required to completely cover the hole 01 12 2006 nbsp 0183 32 Anchor bolt washers are mentioned briefly in a couple places in AISC Steel Design Guide Series 1 quot Column Base Plates quot but no specific washer design recommendatons are given beyond using a heavy plate washer 5 16 quot to 1 2 quot thick when anchoring with oversize holes In Table 14 2 of AISC steel Manual 13 th Ed recommended washer sizes and thicknesses or developed to accommodate lock washers the washer requirements for pretensioned joints prevent local yielding of the material around the hole which can lead to loss of pretension in the bolt More information on the background for washer requirements in the AisC and rCsC specifications canbolts nuts and washers meet The manufacturing quality requirements for high strength bolts nuts and washers are covered in the following specifica tions for high strength bolts ASTM A325 A325M and ASTM A490 A490M for nuts ASTM A563 A563M or ASTM A194 A194M for washers ASTM F436 F436M for direct tension

Specification for Structural Joints Using High Strength Bolts AISC

02 10 2014 nbsp 0183 32 I don t think RCSC and AISC washer requirements strictly apply to this connection because the slot is longer than the code prescribed long slot unless it is 1 1 4 quot bolt but if that were the case the plate would not need to be 5 1 2 long I am guessing it is a 1 2 quot bolt and the code quot long slot quot for a 1 2 quot bolt is 1 1 4 quot long Red Flag This Post Please let us know here why Tapered washers above left are used when the surface being bolted has a sloped surface such as the flange of a channel or an S shape A325 bolts require a washer under the element head or nut being turned to tighten 12 the bolt shown under the nut above right A490 bolts require a washer under both the head and nut AISC amp NISD 2000 17 11 2020 nbsp 0183 32 It is noted that these hole sizes permit a reasonable tolerance for misalignment in setting the bolts and more precision in the adjustment of the base plate or column to the correct centerlines Note that these hole sizes are such that flame cutting will often be required An adequate washer see 7 2 4 should be provided for each anchor rod Because these hole requirements of slip critical connections Section 6 2 1 was modified to permit the use of A490 type bolts with round heads equal or larger in diameter than ASTM F1852 heads without F436 hardened washers Table 6 1 footnote d was added to clarify use of non hardened plate washer to be used in conjunction with an ASTM F436 hardened Revised Washer Requirements in Table 6 1 For many years the bolt spec has required washers that are 5 16 thick and hardened in accordance with ASTM F436 where pretensioned ASTM A490 bolts greater than 1 diameter are used in oversized holes or slots in the outer ply Similarly bolted connections with long slots in the outer ply required 5 16 thick hardened

and STEEL 6410 AISC Specifications for Structural Joints

17 07 2007 nbsp 0183 32 AISC also recommends using plate washers at any and all baseplates where anchor rods may be subject to tension e g moment frames with high bending moments or braced frames in uplift etc and oversized holes are used This is to keep a typical size washer from pulling through the oversized hole in tension The AISC 13th ed manual provides maximum 26 07 2005 nbsp 0183 32 When designing steel column base plates with large oversize holes plate washers are required to cover the hole However all the references I have say that the thickness needs to be designed for the loads Does not say how though I am in Florida and frequently design light structures hangars etc that have significant net uplift forces on the footings Using standard 29 10 2014 nbsp 0183 32 Multiple stacked washers that add up to a thickness of 5 16 quot do not meet the requirement The washer must be structural grade steel but does not need to be hardened A 3 8 quot thick plate washer and a regular F436 washer can be used instead The plate washer doesn t need to be hardened17 11 2020 nbsp 0183 32 The recommended maximum hole sizes for anchor rods in base plates are given in the AISC Steel Construction Manual Table 14 2 It is noted that these hole sizes permit a reasonable tolerance for misalignment in setting the bolts and more precision in the adjustment of the base plate or column to the correct centerlines Note that these hole sizes are such that The AISC Specification for Structural Steel Buildings and various ASTM material standards cover requirements for the use of anchor rods and base plates The FAQs in this section include a discussion of portions of these provisions and subsequent recommendations Additional information is available from AISC Design Guide 1 Base Plate and Anchor Rod Design