2016 AASHTO BRIDGE COMMITTEE AGENDA ITEM: 24 (REVISION 1) SUBJECT: LRFD Bridge Design Specifications: Section 6, Various Articles (2)

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1 2016 AASHTO BRIDGE COMMITTEE AGENDA ITEM: 24 (REVISION 1) SUBJECT: LRFD Bridge Design Specifications: Section 6, Various Articles (2) TECHNICAL COMMITTEE: T-14 Steel REVISION ADDITION NEW DOCUMENT DESIGN SPEC CONSTRUCTION SPEC MOVABLE SPEC MANUAL FOR BRIDGE SEISMIC GUIDE SPEC COASTAL GUIDE SPEC EVALUATION OTHER DATE PREPARED: 2/4/16 DATE REVISED: 6/29/16 AGENDA ITEM: Item #1 Replace Article with the following: High-Strength Structural Fasteners High-Strength Bolts High-strength bolts used as structural fasteners shall conform to ASTM F3125. The required specified minimum tensile strengths of ASTM F3125 bolts shall be taken as specified in Table Type 3 bolts shall be used with weathering steels. Corrosion-resistant coatings may be applied to Grade A325, F1852, and A490 bolts, as specified in ASTM F3125. Table Required Specified Minimum Tensile Strengths Grade ASTM F3125 Bolts Required Specified Minimum Tensile Strength, ksi A F A F Nuts Used with ASTM F3125 Bolts Nuts used with ASTM F3125 bolts shall be as listed in ASTM F3125 as recommended or suitable for the bolt Washers Used with ASTM F3125 Bolts Hardened washers used with ASTM F3125 bolts shall be as listed in ASTM F3125 as recommended or suitable for the bolt. 24-1

2 Direct Tension Indicators Direct tension indicators (DTIs) conforming to the requirements of ASTM F959 may be used in conjunction with bolts, nuts and washers. Captive DTI/nuts shall be considered permissible for use, provided both the DTI and hardened heavy hex nut meet the mechanical property requirements of their respective ASTM standards. DTIs that incorporate a self-indicating feature shall also be considered permissible for use. The use of the self-indicating feature to replace the use of feeler gauges shall be subject to the approval of the Engineer. DTIs installed over oversize or slotted holes in an outer ply shall satisfy the applicable provisions of Article Item #2 Delete Articles , , , and Delete Articles C , C , C , and C Item #3 Add a new Article C as follows: C The ASTM F3125 standard bundles the previous ASTM A325, A325M, A490, A490M, F1852, and F2280 standards together and only the ASTM F3125 standard will be maintained moving forward. ASTM F3125 Grades F1852 and F2280 are the twist-off equivalents of Grades A325 and A490, respectively. Galvanizing is not an acceptable option within ASTM F3125 for Grade A490 or F2280 bolts, but Grade A490 bolts may be coated with a zinc/aluminum coating in accordance with ASTM F1136 or F2833. Rotational capacity testing of the fastener assemblies by the Manufacturer in accordance with Annex A2 of F3125 is required for Grade A325 and A490 fastener assemblies as specified in Article of the AASHTO LRFD Bridge Construction Specifications. Alternative fasteners satisfying the requirements of ASTM F3125 may be used subject to the approval of the Engineer. Item #4 Add a new Article C as follows: C DTIs are washers with protrusions on one face that measure load by compressing the protrusions on the DTI with a proportional reduction in the gap in the spaces between the protrusions. Attaining the required tension is verified by the number of gauge refusals, which are gaps that are too tight to permit the insertion of a feeler gauge of the prescribed thickness. A DTI affixed to a hardened heavy hex nut by the fastener manufacturer is referred to as a captive DTI/nut. An assembly which incorporates a self-indicating feature to signal sufficient compression of the protrusions is referred to as a self-indicating DTI. Installation provisions and verification procedures for DTIs are covered in the AASHTO LRFD Bridge Construction Specifications. Item #5 Add a new Article as follows: Low-Strength Steel Bolts Low-strength steel bolts used as structural fasteners shall conform to ASTM A307 Grade A or B or an equivalent alternative subject to the approval of the Engineer. The required specified minimum tensile strength of 24-2

3 ASTM A307 bolts shall be taken as 60 ksi. Item #6 Add a new Article C as follows: C Low-strength steel bolts, also referred to as unfinished, common, machine, ordinary, or rough bolts, are typically designated as ASTM A307 bolts. The ASTM standard for A307 bolts covers two grades of fasteners, Grades A and B. An equivalent alternative may be used for these bolts subject to the approval of the Engineer. Item #7 Add a new Article as follows: Fasteners for Structural Anchorage Anchor Rods Anchor rods shall conform to ASTM F Nuts Used with Anchor Rods Nuts used with ASTM F1554 anchor rods shall conform to ASTM A563 or ASTM A194 Grade 2H. Nuts to be galvanized shall be heat treated Grade DH or DH3. All galvanized nuts should be lubricated with a lubricant containing a visible dye in accordance with ASTM A563, Supplementary Requirements S1 and S2. Item #8 Add a new Article C as follows: C Fasteners for structural anchorage are covered in a separate article so that other requirements for high-strength bolts are not applied to anchor rods. The term anchor rods, which is used in these Specifications, is considered synonymous with the term anchor bolts which has been used. Item #9 Revise the 11 th through the 16 th bullets of Article as follows: For A 325 and A 490 ASTM F3125 bolts in tension ϕ t = 0.80 For A 307 A307 bolts in tension φ t = 0.80 For ASTM F 1554 F1554 anchor rods bolts in tension φ t = 0.80 For A 307 A307 bolts in shear φ s = 0.75 For ASTM F 1554 F1554 anchor rods bolts in shear φ s = 0.75 For A 325 and A 490 ASTM F3125 bolts in shear φ s = 0.80 Item #10 Revise the 3 rd paragraph of Article as follows: All resistance factors for ASTM A307 Grade C and ASTM F1554 bolts used as anchor bolts rods for the extreme event limit state shall be taken to be

4 In the last sentence of the last paragraph of Article , change anchor bolts to anchor rods. In the 2 nd bullet item in Article C6.16.1, change anchor bolts to anchor rods. In the 1 st sentence of the 3 rd paragraph of Article C , change anchor bolts to anchor rods. In the 3 rd sentence of the 1 st paragraph of Article C , change anchor bolts to anchor rods. Item #11 Revise Table as follows: Constant, A Detail Category times 10 8 (ksi 3 ) A B B 61.0 C 44.0 C 44.0 D 22.0 E 11.0 E 3.9 ASTM F3125, Grades A325 and 17.1 F1852 Bolts in Axial Tension ASTM F3125, Grades A490 and 31.5 F2280 Bolts in Axial Tension Item #12 Revise Table as follows: Threshold Detail Category (ksi) A 24.0 B 16.0 B 12.0 C 10.0 C 12.0 D 7.0 E 4.5 E 2.6 ASTM F3125, Grades A 325 A325 and 31.0 F1852 Bolts in Axial Tension ASTM F3125, Grades A 490 A490 and 38.0 F2280 Bolts in Axial Tension 24-4

5 Item #13 Replace Article with the following: Hardened washers shall be required for connections using ASTM F3125 bolts as specified in Article of the AASHTO LRFD Bridge Construction Specifications. Hardened washers used with ASTM F3125 bolts shall satisfy the requirements specified in Article Direct tension indicators shall not be installed over oversize or slotted holes in an outer ply, unless a hardened washer or a structural plate washer is also provided. Item #14 Delete Article C Item #15 Revise the 1 st paragraph of Article as follows: The nominal shear resistance of a high-strength bolt (ASTM A325 or ASTM A490) (ASTM F3125) or an ASTM A307 bolt (Grade A or B) at the strength limit state in joints whose length between extreme fasteners measured parallel to the line of action of the force is less than 50.0 in. shall be taken as: Item #16 Revise Table as follows: Table Minimum Required Bolt Tension, ASTM F3125 Bolts Required Tension-P t (kip) Grade A325 or F1852 5/ / / / / / / Bolt Diameter, in. Item #17 Grade A490 or F2280 Delete the 4 th paragraph of Article C Delete the 2 nd sentence of the 5 th paragraph of Article C Delete the 6 th, 7 th, and 8 th paragraphs of Article C Item #18 Revise the 1 st sentence of Article C as follows: Properly tightened A325 and A490 ASTM F3125 bolts are not adversely affected by repeated application of the recommended service load tensile stress, provided that the fitting material is sufficiently stiff that the prying force is a relatively small part of the applied tension. 24-5

6 OTHER AFFECTED ARTICLES: None BACKGROUND: Item #1: A new Article on high-strength structural fasteners is proposed to introduce the new ASTM F3125 standard. ASTM F3125 is a new standard for high-strength bolts combining ASTM A325, A325M, A490, A490M, F1852, and F2280. The previous specification designations are being preserved, for now, as grade designations within this standard. The most significant technical change is that Grade A325 bolts no longer have two strength levels, 120 or 105 ksi depending on the bolt diameter; the single strength level is now 120 ksi for all Grade A325 bolts. ASTM F3125 bolts will only have head markings reflecting the grade of the bolts; therefore, an ASTM F3125 Grade A325 bolt will look identical to a bolt meeting the ASTM A325 standard. Until the industry has fully transitioned to the ASTM F3125 standard, bolts will likely be dual-certified under the new and old standards, which presents no concerns for design. ASTM specifications for the twist-off equivalent for Grade A325 and A490 highstrength bolts have existed for several years and are referred to as Grades F1852 and F2280 in the new ASTM F3125 standard. Reference is made in new sub-articles and to the new ASTM F3125 standard for the appropriate nuts and washers to be used with ASTM F3125 bolts. The existing commentary language related to installation of washers is eliminated because installation procedures for washers are typically not the concern of the designer. An attempt has been made (throughout) to eliminate repetition of information already covered in the ASTM F3125 standard, e.g., provisions related to overtapping of zinc-coated nuts and provisions stating that washers, nuts and bolts of any assembly are to be galvanized by the same process, and to eliminate information which is not necessary for design or that is covered in more depth in the AASHTO LRFD Bridge Construction Specifications. Similar revisions incorporating the new ASTM F3125 standard in lieu of the previous standards are proposed to the AASHTO LRFD Bridge Construction Specifications in a separate joint T-4/T-14 Agenda item. The current Article is now a new Article under high-strength structural fasteners, and the title of the article is changed from Load Indicator Devices to Direct Tension Indicators since direct tension indicators (DTIs) are the only load indicator devices that are currently used. Reference is made to both captive DTI/nuts and self-indicating DTIs, which are permitted for use in the AASHTO LRFD Bridge Construction Specifications. A reference is added directing the Engineer to the washer requirement for DTIs installed over a slotted or oversize hole in the outer ply currently specified in Article of the AASHTO LRFD Bridge Design Specifications. The last line of the current article is also eliminated because currently there are no alternative direct tension indictors. The commentary in a new accompanying Article C is also expanded to include general definitions of the various types of DTIs. Revisions are also proposed to the DTI provisions in the AASHTO LRFD Bridge Construction Specifications in a separate joint T-4/T-14 Agenda Item to better align the AASHTO Specifications with current DTI manufacturing practices, including revisions to the DTI installation and verification procedures. Item #5: A new Article is proposed to cover low-strength steel bolts, also referred to as unfinished, common, machine, ordinary, or rough bolts, which are typically designated as ASTM A307 bolts. Item #7: A new Article is proposed to cover fasteners for structural anchorage separately from highstrength structural fasteners so that other requirements for high-strength bolts are not applied to anchor rods. The term anchor bolts has been changed to anchor rods throughout Section 6, and commentary language has been added to indicate that the two terms are synonymous. ASTM A307 Grade C bolts are eliminated in favor of ASTM F1554 anchor rods, which are the most commonly used anchor rods, and also because ASTM A307 Grade C bolts have been eliminated from the ASTM A307 specification. Item #9: Revisions are made to the resistance factor definitions for high-strength bolts to reflect the new ASTM F3125 standard. Item #11: Revisions are made to Tables (Detail Category Constant, A) and (Constant Amplitude Fatigue Threshold) for fatigue of bolts in axial tension to reflect the new ASTM F3125 standard. 24-6

7 Item #13: A list of the conditions/exceptions where hardened washers are required for connections using F3125 bolts is currently provided in Article of the AASHTO LRFD Bridge Design Specifications. It is proposed herein that reference be made instead to a similar list specified in Article of the AASHTO LRFD Bridge Construction Specifications for these conditions where hardened washers are required. Updates to Article are proposed in a separate joint T-4/T-14 Agenda Item. This is recommended for ease of future specification maintenance, and because the fabricator typically decides the need for and placement of washers. Item #15: This item includes remaining miscellaneous editorial changes to reflect the new ASTM F3125 standard. Item #16: Revisions are made to the minimum required bolt tension values in Table to reflect the new strength level of 120 ksi for Grade A325 or F1852 high-strength bolts over 1 inch in diameter. Also included are editorial changes to the Commentary for consistency with the revisions made to the table, and to eliminate three duplicate paragraphs that were mistakenly introduced in the 7 th Edition. ANTICIPATED EFFECT ON BRIDGES: Allows the use of a single specification for high-strength bolts, which is more easily maintained by ASTM and reduces the need for repetitive specifications and minor exceptions within the AASHTO Specifications. Will allow for more consistency in the specification, provision, and testing of all types of high-strength bolts. The use of a single higher strength level for Grade A325 and F1852 bolts over 1 inch in diameter may make larger diameter bolts more attractive for design. REFERENCES: Standard Specification for High Strength Structural Bolts, Steel and Alloy Steel, Heat Treated, 120 ksi and 150 ksi Minimum Tensile Strength, ASTM F3125, January OTHER: None 24-7