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ITEM 712 – STRUCTURAL METAL


712.1 Structural Steels

712.1.1 General

Steel shall be furnished according to the following Specifications. Unless otherwise specified, structural carbon rivet steel shall be furnished.

712.1.2 Structural Steel

a. Carbon Steel. Unless otherwise specified, structural carbon steel for riveted, bolted or welded construction shall conform to Structural Steel, AASHTO M183
b. Eyebars. Steel for eyebars shall be of a weldable grade. This grade includes structural steel conforming to: Structural Steel, AASHTO M 183; Highway Strength Low Alloy Structural Steel with 344.5 MPa Minimum Yield Point to 100 mm thick, AASHTO M 222 (ASTM A 588 with Supplementary Requirement SI of AASHTO M 222 mandatory).

712.1.3 High-Strength Low Alloy Structural Steel

It shall conform to: High-Strength Low-Alloy Columbium-Vanadium Steels of Structural Quality, AASHTO M 223, High-Strength Low Alloy Structural Steel with 344.5 MPa Minimum Yield Point to 100 mm thick, AASHTO M 222.
712.1.4 High-Strength Low Alloy Structural Steel for Welding
It shall conform to:
a. High-Strength Low Columbium-Vanadium Steels of Structural Quality, Grade50, AASHTO M 223 (ASTM A 572 with supplementary requirements S2 of AASHTO M 223 mandatory).
b. High-Strength Low Alloy Structural Steel with 344.5 MPa Minimum Yield Point to 100 mm thick, AASHTO M 222 (ASTMA 588 in Supplementary Requirement S1 of AASHTO M 222 mandatory).
 
712.1.5 High-Strength Structural Steel for Riveted or Bolted Construction

It shall conform to:
a. High-Strength Low Alloy Columbium – Vanadium Steel of Structural Quality, and AASHTO M 223.

b. High-Strength Low Alloy Structural Steel with 344.5 MPa Minimum Yield Point to 100mm thick, AASHTO M 222.

712.1.6 High-Yield Strength, Quenched and Tempered Alloy Steel Plate

It shall conform to:
a. High-Yield Strength, Quenched and Tempered Alloy Steel Plate, suitable forwelding, ASTM A 514.

b. High-Strength Alloy Steel Plates, Quenched and Tempered for pressure vessels, ASTM A 517.

c. Quenched and tempered alloy steel structural shapes and seamless mechanical tubing meeting all the mechanical and chemical requirements of A 514/A 517 steel, except that the specified maximum tensile strength maybe 964.6 MPa for structural shapes and 999.05 MPa for seamless mechanical tubing shall be considered as A 514/A 517 steel.

712.1.7 Structural Rivet Steel

It shall conform to Steel Structural Rivets AASHTO M 228, Grade I (ASTM A 502, Grade I).

712.1.8 High-Strength Structural Rivet Steel

It shall conform to Steel Structural Rivets AASHTO M 228, Grade 2 (ASTM A 502, Grade 2).

712.1.9 High-Strength Bolts

Bolts, nuts circular washers shall conform to High-Strength Bolts for Structural Steel Joints, including Suitable Nuts and Plain Hardened Washer, AASHTO M 164 (ASTM A 325).

High-strength bolts for structural steel joints including suitable nuts and plain hardened washers shall conform to either AASHTO M 164 (ASTM A 325) or AASHTO M 253. When M 164 type 3 bolts are specified, they along with suitable nuts and washers shall have an atmospheric corrosion resistance approximately two times that of carbon steel with copper. 

Bolts and nuts manufactured to AASHTO M 164 (ASTM A 325) are identified by proper marking as specified on the top of the bolt heads and on one face of the nuts for three different types.

Bolts manufactured to AASHTO M 253 shall be identified by marking on the top of the head with the symbol A 490 and the nuts shall be marked on one face with the legend “2H” or “DH”.

Bolt and nut dimensions shall conform to the dimensions shown in Table 712.1 and to the requirements for Heavy Hexagon Structural Bolts and for Heavy Semi-Finished Hexagon Nuts given in ANSI Standard B 18.2.1 and B 18.2.2, respectively.

Circular washers shall be flat and smooth and their nominal dimensions shall conform to the dimensions given in Table 712.2 except that for lock pin and collar fasteners, flat washers need not be used, unless slotted or oversized holes are specified.

Bevelled washers for American Standard Beams and Channels or other sloping faces shall be required and shall be square or rectangular, shall taper in thickness, and shall conform to the dimensions given in Table 712.2.When necessary, washer may be clipped on one side to a point not closer than 0.875 (7/8) of the bolt diameter from the center of the washer.

Other fasteners or fasteners assemblies which meet the Materials, Manufacturing, and Chemical Composition requirements of AASHTO M 164 (ASTM A 325) or AASHTO M 253 and which meet the Mechanical Property requirements of the same specification in full-size tests and which have body diameter and bearing areas under the head and nut, or other equivalent, not less than those provided by a bolt and nut of the same nominal dimensions prescribed in the previous paragraph, may be used. Such alternate fasteners may differ in other dimensions from those of the specified bolts and nuts. Their installation procedure may differ from those specified in AASHTO Bridge Specification. Article 2.10.20 (D) and their inspection may differ from that specified in Article 2.10.20 (E). When a different installation procedure or inspection is used, it shall be detailed in a supplemental specification applying to the alternate fastener and that specification must be approved by the Engineer.

Subject to the approval of the Engineer, high strength steel lock-pin and collar fasteners may be used as an alternate for high strength bolts or rivets as shown on the Plans. The shank and head of the high strength steel lock-pin and collar fasteners shall meet the requirements of the preceding paragraph. Each fasteners shall provide a solid shank body of sufficient diameter to provide tensile and shear strength equivalent to or greater than the bolt or rivet specified, shall have a cold forged head on one end, of type and dimensions as approved by the Engineer, a shank length suitable for material thickness fastened, locking grooved, break neck groove and pull grooves (all annular grooves) on the opposite end. Each fasteners shall provide a steel locking collar of proper size for shank diameter used which by means of suitable installation tools, is cold swaged into the locking grooves forming a head for the grooved end of the fastener after the pull groove section has been removed. The steel locking collar shall be a standard product of an established manufacturer of lock-pin and collar fasteners, as approved by the Engineer.

712.1.10 Copper Bearing Steels

When copper bearing steel is specified, the steel shall contain not less than 0.2 percent of copper.

712.2 Forgings

Steel forgings shall conform to the specifications for Steel Forgings, Carbon and Alloy, for General Industrial Use, AASHTO M 102, (ASTM A 668, Classes C, D, F& G).

712.3 Pins and Rollers

Pins and rollers more than 228.6 mm in diameter shall be annealed carbon-steel forgings conforming to AASHTO M 102, Class C1.

Pins and rollers 228.6 mm (9 inches) or less in diameter shall be either annealed carbon-steel forgings conforming to AASHTO M 102 (ASTM A 668),Class C1 or cold finished carbon-steel shafting conforming to AASHTO M 169,grade 1016 to 1030 (ASTM A 108) inclusive, with a minimum Rockwell Scale B Hardness of 85. Material not meeting the specifications for hardness maybe accepted provided it develops a tensile strength of 482.3 MPa and a yield point of 248.04 MPa.

Threads for pins shall conform to the ANSI B1.1 Coarse Thread Series, Class 2A. Pin ends having a diameter of 35mm or more shall be threaded (12 threads to every 5 cm)

Table 712.1 – Nominal Bolt and Nut Dimensions

Nominal Bolt Size
(Diameter)mm
Heavy Hexagon Structural Bolts
Dimensions in mm
Heavy Semi-Finished Hexagonal Nuts
Dimensions in mm
Width of Head Across Flats
Height of Head
Thread Length
Width Across Flats
Height
12
21
7
25
21
12
15
26
9
31
26
15
18
31
11
34
31
18
21
35
13
37
35
21
25
40
15
43
40
24
28
45
17
50
45
27
31
50
19
50
50
30
34
54
21
56
54
33
37
59
23
56
59
36


Table 712.2 – Nominal Washer Dimensionsa

Circular Washer
Square or Rectangular Bevelled Washers for American Standard Beams and Channels
Bolt
Size Diameter mm
Nominal Outside Diameterb mm
Nominal Diameter of Hole
Thickness
Minimum Side Dimension
Mean Thickness mm
Slope or Taper in Thickness mm
Minimum mm
Maximum mm
12
15
19
22
25
28
31
34
37
43
50
Over 50 to 100 incl.
26
32
36
43
50
56
62
68
75
84
93
2D – 12
13
16
20
23
26
31
34
37
40
46
53
D+3
2
3
3
3
3
3
3
3
3
c4
4
d6
4
4
4
4
4
4
4
4
4
c7
7
d8
43
43
43
43
43
43
43
43
43
-
-
-
7
7
7
7
7
7
7
7
7
-
-
-
40
40
40
40
40
40
40
40
40
-
-
-

a Dimensions in mm
b May be exceeded by 6 mm
c 4 mm nominal
d 6 mm nominal

712.4 Castings

Castings shall conform to the requirements of the following Specifications:
Steel castings for Highway Bridges-AASHTO M 192, Class 70 shall be furnished unless otherwise specified.

Chromium Alloy Steel Castings-AASHTO M 163 (ASTM A 296), Grade CA-15shall be furnished unless otherwise specified.

Gray Iron Castings – AASHTO M 105 Class No. 30 shall be furnished unless otherwise specified. Iron castings shall be true to pattern in form and dimensions, free from pouring faults, sponginess, cracks, blow holes, and other defects in position affecting their strength and value for the service intended. Casting shall be boldly filleted at angles and the arises shall be sharp and perfect. All castings must be sandblasted or otherwise effectively cleaned of seals and sand so as to present a smooth, clean and uniform surface.

Malleable Castings – ASTM A 47. Grade No. 35018 shall be furnished unless otherwise specified. The requirements for workmanship, finishing, and cleaning shall be the same as above for gray iron castings.

712.5 Steel Grid Floors

All steel for grid floors shall conform to the requirements of AASHTO M 183 or AASHTO M 222. Steel grid floors can be weathering steel, galvanized or painted. Unless the floors are of weathering steel or galvanized, the material shall have a minimum copper content of 0.2%.

Unless painting of floors is specified in the Special Provisions, open type floors shall be galvanized.

712.6 Steel Pipe

It shall conform to the requirements of ASTM A 53, ASTM A 120. AASHTO M 222and ASTM A 618, as shown on the Plans or in the Special Provisions.

Standard weight pipe shall be furnished unless otherwise shown on the Plans or in the Special Provisions.

712.7 Galvanized Metal

When galvanized structural steel shapes, plates, bars and their products are specified, they shall be galvanized in accordance with the requirements of AASHTO M 111.

712.8 Sheet Lead

It shall conform to the requirements of ASTM B 29 for common desilverized lead.
The sheets shall be of uniform thickness and shall be free from cracks, seams, slivers, scale and other defects. Unless otherwise specified, lead sheets shall be 3.8 mm in thickness with a permissible tolerance of 0.75 mm plus or minus.

712.9 Welded Stud Shear Connectors

Shear connector studs shall conform to the requirements of AASHTO M 169 (ASTMA 108) for cold finished carbon steel bars and shafting, cold drawn bar, Grades 1015, 1018 or 1020, either semi-skilled or fully-skilled. If flux retaining caps are used, the steel for the caps shall be of a low carbon grade suitable for welding and shall comply with ASTM A 109 for cold rolled carbon steel strip.
 
Tensile properties as determined by tests of bar stock after drawing or of finished studs shall conform to the following requirements:

Tensile strength (minimum)
Yield strength* (minimum)
Elongation (minimum)
Reduction in area (minimum)
413.4 MPa
344.5 MPa
20 percent in 50 mm
50 percent
* As determined by 0.2 percent offset method.

Tensile properties shall be determined in accordance with applicable sections of ASTM A 370 for mechanical testing of steel products. Tensile tests of finished studs shall be made on studs welded to test plates using a test fixture with dimensions similar to those shown in Table 712.3.

If fracture occurs outside the middle half of the gage length, the test shall be repeated.

Finished studs shall be of uniform quality and conditions, free from injurious laps, fins, seams, cracks, twists, bends or other injurious defects. Finish shall be produced by cold drawing, cold rolling or machining.

The studs shall conform to the dimensions given in Table 712.3.

The Contractor shall furnish the manufacturer’s certification that the studs as delivered are in accordance with the material requirements of this Item. Certified copies of in-plant quality control test reports shall be furnished to the Engineer upon request.

Table712.3 – Welded Stud Shear Connector Standard Dimensions and Tolerances mm
Shank
Head
Diameter (c)
Length (L)
Diameter (H)
Thickness (T)
19.05 + 0.00
           - 0.381
101.6 + 1.575
           - 3.175
31.75 ± 0.40
9.53 min.
22.23 + 0.000
           - 0.381
101.6 + 1.575
           - 3.175
34.93 ± 0.40
9.53 min.


*           Length includes thickness of head. Standard lengths is 101.6 mm but other lengths may be obtained by special order. 

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