SPECIFICATIONS FOR MATERIALS

Standard Specification for Corrugated Sheet Steel Beams for Highway Guardrail

AASHTO DESIGNATION: M180-79

1. SCOPE

1.1 This specification covers Corrugated sheet steel prepared for use as beams in highway guardrails. Two classes and four types of guardrail are provided as follows:

1.1.1 Classes

Class A-Base metal nominal thickness-0.105 in. (2.67 mm).

Class B-Base metal nominal thickness-0.135 in. (3.43 mm).

1.1.2 Types

Type 1 -Zinc coated, 1.80 ounces per square foot (550 g/m') minimum single-spot.

Type 2 -Zinc coated, 3.60 ounces per square foot (1100 g/ml) minimum single-spot.

Type 3-Beams to be painted.

Type 4-Beams of corrosion resistant steel.

2. BASIS OF PURCHASE

2.1 Orders for guardrail under this specification shall include the following information, as required, to describe adequately the desired material:

2.1.1 Quantity (linear feet or number of pieces),

2.1.2 Class of Guardrail,

2.1.3 Type of Guardrail,

2.1.4 Effective length of beam section (12'-6" or 25'-0") (3.8 or 7.6 m),

2.1.5 Shape (W-Beam or Thrie Beam), and

2.1.6 Exceptions to this specification, or special requirements, if any

3. BASE METAL MANUFACTURE

3.1 The beam, transition, end and buffer sections shall consist of sheet made of open hearth, electric furnace or basic oxygen steel.

3.2 Mechanical Properties:

3.2.1 The mechanical properties of the base metal shall conform to the following requirements:

3.2.1.1 Beams and transition sections:

Yield Point, minimum, 50,000 psi (345 MPa)

Tensile Strength, minimum, 70,000 psi (483 MPa)

Elongation, in 2 inch (50 mm), minimum, 12 percent

3.2.1.2 End and buffer sections:

Yield Point, minimum, 33,000 psi (227 MPa)

Tensile Strength, minimum, 45,006 psi (310 MPa)

3.2.2 Test specimens for mechanical properties shall be prepared and tested as specified in ASTM A 525 except that correction for thickness of zinc coated specimens shall be 0.003 in. (0.08 mm) for Type 1 beam and 0.006 in. (0.15 mm) for Type 2 beam.

3.3 Chemical Composition

3.3.1 The chemical composition of the base metal for Type 4 beams shall be as approved by the Engineer.

4. SHEET OR BEAM THICKNESS

4.1 The nominal thickness for the finished beam or sheet shall conform to the requirments as prescribed in Table 1

4.2 For fabricated beams, thickness measurements will be made on tangent portions of the cross-section.

5. SHEET WIDTH

5.1 The beam elements shall be formed from sheets having nominal widths of 19 inches (483 mm) for W-Beams and 29'12 inches (749 mm) of Thrie Beams. Tolerance from the nominal width of minus '18 inch (3.2 mm) will be permissible.

NOTE: The requirements of paragraph 5.1 are intended to define the minimum width sheet permissible. Calculation of exact width dimensions from Figures 1 and 2 shows that the finished product may slightly exceed these widths. However, the dimensions of Figures 1 and 2 can be met within allowable tolerance by using the nominal widths. Use of sheets slightly greater than the nominal widths is permissible provided the tolerances in Figures 1 and 2 are met.

6. GALVANIZED BEAMS

6.1 The beams may be galvanized before or after fabrication. The zinc used for the coating shall be as prescribed in AASHTO M 120, and shall be at least equal to the grade designated as "Prime Western."

6.2 The weight of coating shall conform to the requirements prescribed in Table 2 for the types specified. The weight of coating is the total amount of galvanizing on both sides of a sheet or beam, expressed as ounces per square foot (g/m²) of sheet.

6.3 The sheets or beams shall be of prime finish, that is, free from injurious defects such as blisters, flux, and uncoated spots. Uncoated edges resulting from shearing or punching will not be considered objectionable.

6.4 The coating shall be smooth, free of beading or sharp projections along the edges and shall adhere tenaciously to the surface of the metal. The adherence of the zinc coating to the surface of the base metal shall be determined by cutting or prying with a stout knife, applied with considerable pressure in a manner tending to remove a portion of the coating by paring or whittling, and it shall not be possible to peel any portion of the coating so as to expose the base metal.

6.5 The test specimen size and method of tests for determining the weight of coating shall be as prescribed in AASHTO T 65. At the option of the Engineer, material may be accepted on the basis of magnetic gage determinations made in accordance with ASTM E 376.

TABLE 1

 TABLE 2

7. PAINTED BEAMS

7.1 Beams which are to be painted shall be cleaned and shop painted with one coat of rust-inhibitive primer. The primer shall have a tough and durable surface and shall be thoroughly dry before the sheets are handled or packed for shipment.

8. CORROSION RESISTANT BEAMS

8.1 Beams of corrosion resistant steel shall not be painted or galvanized. They shall be so handled and stored that the traffic face of these beams, used in a continuous run of guardrail, shall not show a distinctive color differential.

9. END OR BUFFER SEMONS

9.1 End or buffer sections shall be of the same or greater thickness of metal and the same Type as the beam to which it is attached or the engineer may specify the minimum thickness of metal and Type.

10. FABRICATION

10.1 The beams and end or buffer sections shall be shaped and punched in conformance with the requirements shown in Figures 1 and 2. Transition sections shall be fabricated in accordance with Figure 4 and shall provide a smooth and uniform transition between beams. They shall be ready for assembly when delivered. Only drilling or cutting necessary for special connections and for sarnpling will be permitted in the field. Warped or deformed beams will be rejected. Beams to be erected on a radius of 150 feet (45 m) or less shall be shop curved to the appropriate curvature of the installation.

11. CONNECTIONS AND SPLICES

11.1 All connections or splices shall be formed with oval shoulder button headed bolts to minimize projections on the road side of the guardrail. Unless otherwise specified, bolts and nuts for Types 1, 2 and 3 beams shall conform to or exceed the requirements of ASTM A 307 and shall be hot-dip zinc coated in accordance with the requirements of AASHTO M 232, Class C. When specified by the Engineer to be mechanically galvanized, bolts and nuts shall be mechanically zinc coated and the coating shall conform to the coating thickness, adherence and quality requirements of AASHTO M 232, Class C. Bolts and nuts for Type 4 beams shall be of an approved corrosion resistant material and conform to or exceed the requirements of ASTM A 307. Splice and post bolts and nuts shall conform to one of the configurations shown in Figure 3. Either of the alternate configurations may be furnished unless otherwise specified by the Engineer.

12. WASHERS AND BACK-UP PLATES

12.1 Washers shall be rectangular as shown in Figure 1. Washers for Types 1, 2 and 3 beams shall be galvanized in accordance with the requirements of AASHTO M 232. Washers for Type 4 beams shall be of an approved corrosion resistant steel. Back-up plates if specified for use at nonsplice points shall consist of one-foot (305 mm) sections of beams and shall be ofthe same Class and Type specified for the full length beams.

13. GALVANIZING REPAIR

13.1 Where the galvanizing on guardrail or fittings has been damaged, the coating shall be repaired by regalvanizing or the surface repaired by painting with two coats of zinc dust-zinc oxide paint confonning to Federal Specification TT-P-641 or MIL-P-21035.

14. MARKING

14.1 Each beam element shall be identified by the following:

Name or Brand of Manufacturer,
Identification Symbols or Code for Heat Number and Coating Lot,
AASHTO Specification Number, and
Class and Type.

14.2 Markings shall not be placed at such a location that they will be obscured after erection,

or in a manner that the brand will be conspicuous to any traffic. Markings placed on the traffic face of the beam shall be placed in the valley of the center corrugation and shall be die imprinted with letters and numerals not exceeding one-half inch in height.

14.3 Marking material shall be such as to resist obliteration during storage, transportation and erection.

14.4 Markings for end sections and back-up plates may be on durable tags securely attached to each section or bundle except that when specified by the Engineer, each individual piece shall be marked.

15. BASIS OF ACCEPTANCE

15.1 All material shall be subject to inspection and sampling at the fabricating plant, warehouse or after delivery to the site of construction.

15.2 Acceptance by Sampling:

15.2.1 The Engineer may take one piece of guardrail, a back-up plate, and end or buffer section from each 200 pieces in a lot, or from each lot if less than 200 pieces are included therein, for determination of comphance with specification requirements. If one piece fails to meet, two other pieces shall be tested. If either of these pieces fail to conform to the requirements of this specification, the lot of material represented by these samples shall be rejected. A lot shall be considered that quantity of material offered for inspection at one time which bears the same heat and coating identification.

15.3 Acceptance by Brand Registration and Guarantee

15.3.1 By mutual agreement between the fabricator and Engineer, acceptance may be based upon a Brand Registration and Guarantee filed with the Engineer by the fabricator. For acceptance of a brand, the fabricator shall furnish a Brand Registration and Guarantee meeting the approval of the Engineer and showing the brand name or designation, the manner in which it will appear on the fabricated beams, the typical mechanical properties, chemical composition if specified, the class and type of guardrail, and other specified properties. lie fabricator shall also guarantee that as long as material is furnished under that brand and designation, it will conform fully to the requirements of the specifications and shall be replaced without cost to the Engineer when found not in conformity with any of the specified requirements. The Brand Registration and Guarantee shall be sworn to for the fabricator by a person having legal authority to bind the company. Upon approval of a Brand Registration and Guarantee, that brand will be accepted without further certification. If, in subsequent actual field use, there is evidence of niisbranding as determined by random sampling and detection of inadequate tensile strength, yield strength, elongation, improper chemical composition, inadequate or improper coating, deficient thickness or improper fabrication, the material will be rejected and approval for further use withdrawn until subsequently reapproved. Samples for test of any material offered for use may be taken at any time deemed desirable by the Engineer.

15.3.2 The manufacturer or fabricator shall make such tests and measurements as necessary to insure that the material produced complies with all specification requirements. These tests and measurements shall be so identified by the identification symbols or code used on the beam that the manufacturer can produce specific reports showing these test results. Copies of reports of these tests shall be kept on file and shall be submitted to the Engineer upon request.

15.3.3 The brand shall be removed or obliterated by the manufacturer or fabricator on all material where control tests, as outlined herein, do not show conformance to this specification.