1、Section 11 STEEL STRUCTURES 11.1 GENERAL 11.1.1 Description This work shall consist of furnishing, fabricating, and erecting steel structures and structural steel portions of other structures in accordance with these Specifications, the Special Provisions and the details shown on the plans. The stru
2、ctural steel fabricating plant shall be certified under the AISC Quality Certification Program, Category I. The fabrication of fracture critical members shall be Category III. Details of design which are permitted to be selected by the Contractor shall conform to Division I of these Specifications.
3、Painting shall conform to the provisions of Section 13, “Painting,” of these Specifications. Falsework used in the erection of structural steel shall conform to the provisions of Section 3, “Temporary Works,” of these Specifications. Structural components designated on the plans or in the special pr
4、ovisions as “fracture critical” shall conform to the provisions of Chapter 12 of the ANSI/AASHTO/ AWS D1.5 Bridge Welding Code. Welding and weld qualification tests shall conform to the provisions of the current ANSI/AASHTO/AWS D1.5 Bridge Welding Code. 11.1.2 Notice of Beginning of Work The Contrac
5、tor shall give the Engineer ample notice of the beginning of work at the mill or in the shop, so that in- spection may be provided. The term “mili” means any rolling mill or foundry where material for the work is to be manufactured. No material shall be manufactured, or work done in the shop, before
6、 the Engineer has been so notified. 11.1.3 Inspection Structural steel will be inspected at the fabrication site. The Contractor shall furnish to the Engineer a copy of all mill orders and certified mill test reports. Mill test reports shall show the chemical analysis and physical test results for e
7、ach heat of steel used in the work. With the approval of the Engineer, certificates of com- pliance shall be furnished in lieu of mill test reports for material that normally is not supplied with mill test re- ports, and for items such as fills, minor gusset plates and similar material when quantiti
8、es are small and the mater- ial is taken from stock. Certified mill test reports for steels with specified impact values shall include, in addition to other test re- sults, the results of Charpy V-notch impact tests. When fine grain practice is specified, the test report shall confirm that the mater
9、ial was so produced. Copies of mill orders shall be furnished at the time orders are placed with the manufacturer. Certified mill test reports and Certificates of Compliance shall be furnished prior to the start of fabrication of material covered by these reports. The Certificate of Compliance shall
10、 be signed by the manufacturer and shall certify that the material is in conformance with the specifications to which it has been manufactured. Material to be used shall be made available to the Engineer so that each piece can be examined. The Engi- neer shall have free access at all times to any po
11、rtion of the fabrication site where the material is stored or where work on the material is being performed. 11.1.4 Inspectors Authority The Inspector shall have the authority to reject materi- als or workmanship which do not fulfill the requirements of these Specifications. In cases of dispute, the
12、 Contractor may appeal to the Engineer, whose decision shall be final. Inspection at the mill and shop is intended as a means of facilitating the work and avoiding errors, and it is ex- pressly understood that it will not relieve the Contractor of any responsibility in regard to defective material o
13、r workmanship and the necessity for replacing the same. The acceptance of any material or finished members by the Inspector shall not be a bar to their subsequent rejec- tion, if found defective. Rejected materials and workman- 565 566 HIGHWAY BRIDGES 11.1.4 ship shall be replaced as soon as practic
14、al or corrected by the Contractor. 11.2 WORKING DRAWINGS The Contractor shall expressly understand that the En- gineers approval of the working drawings submitted by the Contractor covers the requirements for “strength and detail,” and that the Engineer assumes no responsibility for errors in dimens
15、ions. Working drawings must be approved by the Engineer prior to performance of the work involved and such ap- proval shall not relieve the Contractor of any responsibil- ity under the contract for the successful completion of the work. 11.2.1 Shop Drawings The Contractor shall submit copies of the
16、detailed shop drawings to the Engineer for approval. Working drawings shall be submitted sufficiently in advance of the start of the affected work to allow time for review by the Engineer and corrections by the Contractor without delaying the work. Working drawings for steel structures shall give fu
17、ll detailed dimensions and sizes of component parts of the structure and details of all miscellaneous parts, such as pins, nuts, bolts, drains, etc. Where specific orientation of plates is required, the di- rection of rolling of plates shall be shown. Working drawings shall specifically identify eac
18、h piece that is to be made of steel which is to be other than AASHTO M 270 (ASTM A 709) Grade 36 steel. 11.2.2 Erection Drawings The Contractor shall submit drawings illustrating fully his or her proposed method of erection. The drawings shall show details of all falsework bents, bracing, guys, dead
19、-men, lifting devices, and attachments to the bridge members: sequence of erection, location of cranes and barges, crane capacities, location of lifting points on the bridge members, and weights of the members. The plan and drawings shall be complete in detail for all anticipated phases and conditio
20、ns during erection. Calculations may be required to demonstrate that allowable stresses are not exceeded and that member capacities and final geometry will be correct. 11.2.3 Camber Diagram A camber diagram shall be furnished to the Engineer by the Fabricator, showing the camber at each panel point
21、in the cases of trusses or arch ribs, and at the location of field splices and fractions of span length (V4 points mini- mum) in the cases of continuous beam and girders or rigid frames. The camber diagram shall show calculated cam- bers to be used in preassembly of the structure in accor- dance wit
22、h Article 11.5.3. 11.3 MATERIALS 11.3.1 Structural Steel 11.3.1.1 General Steel shall be furnished according to the following specifications. The grade or grades of steel to be furnished shall be as shown on the plans or specified. All steel for use in main load-carrying member com- ponents subject
23、to tensile stresses shall conform to the ap- plicable Charpy V-notch Impact Test requirements of AASHTO M 270 (ASTM A 709). Welded girders made of ASTM A 709, Grade HPS70W steels shall be fabricated in accordance with the AASHTO Guide Specijcations for Highway Bridge Fab- rication with HPS70 W Steel
24、, which supplements the ANSI/AASHTO/AWS DIS Bridge Welding Code. 11.3.1.2 Carbon Steel Unless otherwise specified, structural carbon steel for bolted or welded construction shall conform to: Struc- tural Steel for Bridges, AASHTO M 270 (ASTM A 709) Grade 36. 11.3.1.3 High-Strength Low-Alloy Structur
25、al Steel High-strength low-alloy steel shall conform to: Structural Steel for Bridges, AASHTO M 270 (ASTM A 709) Grades 50 or 50W. 11.3.1.4 High-Strength Low-Alloy, Quenched and Tempered Structural Steel Plate High-strength, low-alloy quenched and tempered steel plate shall conform to AASHTO M 270 (
26、ASTM A 709) Grade 70W, or Grade HPS7OW. 11.3.1.5 High-Yield Strength, Quenched and Tempered Alloy Steel Plate High-yield strength, quenched, and tempered alloy steel plate shall conform to: _ 11.3.1.5 DIVISION II-CONSTRUCTION 5 67 (a) Structural Steel for Bridges, AASHTO M 270 (ASTM A 709) Grades 10
27、0 or 1OOW. (b) Quenched and tempered alloy steel structural shapes and seamless mechanical tubing, meeting all of the me- chanical and chemical requirements of AASHTO M 270 (ASTM A 709) Grades 100 or 1OOW steel, except that the specified maximum tensile strength may be 140,000 psi for structural sha
28、pes and 145,000 psi for seamless mechanical tubing, shall be considered as AASHTO M 270 (ASTM A 709) Grades 100 and 1OOW steel. 11.3.1.6 Eyebars Steel for eyebars shall be of a weldable grade. These grades include structural steel conforming to: (a) Structural Steel for Bridges, AASHTO M 270 (ASTM A
29、 709) Grade 36. (b) Structural Steel for Bridges, AASHTO M 270 (ASTM A 709) Grades 50 and 50W. (ASTM A 563) Grades DH, DH3, C, C3, and D. Nuts for AASHTO M 253 (ASTM A 490) bolts shall conform to the requirements of AASHTO M 291 (ASTM A 563) Grades DH and DH3. Nuts to be galvanized (hot-dip or mecha
30、nically gal- vanized) shall be heat treated Grade DH or DH3. Plain (ungalvanized) nuts shall have a minimum hardness of 89 HRB. Nuts to be used with AASHTO M 164 (ASTM A 325) Type 3 bolts shall be of Grade C3 or DH3. Nuts to be used with AASHTO M 253 (ASTM A 490) bolts shall be of Grade DH3. All gal
31、vanized nuts shall be lubricated with a lubricant containing a visible dye. Black bolts must be oily to touch when delivered and installed. Washers shall be hardened steel washers conforming to the requirements of AASHTO M 293 (ASTM F 436) and Article 11.5.6.4.3. 11.3.1.7 Structural bing 11.3.2.2 Id
32、entifying Marks Structural tubing shall be either cold-formed welded or seamless tubing conforming to ASTM 500, Grade B or hot-formed welded or seamless tubing conforming to ASTh4 501. 11.3.2 High-Strength Fasteners 11.3.2.1 Material High-strength bolts for structural steel joints shall con- form to
33、 either AASHTO M 164 (ASTM A 325) or AASHTO M 253 (ASTM A 490). When high-strength bolts are used with unpainted weathering grades of steel, the bolts shall be Type 3. The supplier shall provide a lot number appearing on the shipping package and a certification noting when and where all testing was
34、done, including rotational capacity tests, and zinc thickness when galvanized bolts and nuts are used. The maximum hardness for AASHTO M i64 (ASTM A 325) bolts 1 inch or less in diameter shall be 33 HRC. Proof load tests (ASTM F 606 Method 1) are required for the bolts. Wedge tests of full-sized bol
35、ts are required in accordance with Section 8.3 of AASHTO M 164. Gal- vanized bolts shall be wedge tested after galvanizing. Proof load tests (AASHTO M 291) are required for the nuts. The proof load tests for nuts to be used with galva- nized bolts shall be performed after galvanizing, overtap- ping,
36、 and lubricating. Except as noted below, nuts for AASHTO M 164 (ASTM A 325) bolts shall conform to AASHTO M 291 AASHTO M 164 (ASTM A 325) for bolts and the specifications referenced therein for nuts require that bolts and nuts manufactured to the specification be identified by specific markings on t
37、he top of the bolt head and on one face of the nut. Head markings must identify the grade by the symbol “A 325,” the manufacturer and the type, if Qpe 2 or 3. Nut markings must identify the grade, the manufacturer and if Type 3, the type. Markings on direct tension indicators must identify the manuf
38、acturer and Qpe “325.” Other washer markings must identify the manufacturer and if Type 3, the type. AASHTO M 253 (ASTM A 490) for bolts and the specifications referenced therein for nuts require that bolts and nuts manufactured to the specifications be identified by specific markings on the top of
39、the bolt head and on one face of the nut. Head markings must identify the grade by the symbol “A 490,” the manufacturer and the type, if Type 2 or 3. Nut markings must identify the grade, the manufacturer and if Type 3, the type. Markings on direct tension indicators must identify the manufacturer a
40、nd Type “490.” Other washer markings must identify the manufacturer and if Type 3, the type. 11.3.2.3 Dimensions Bolt and nut dimensions shall conform to the require- ments for Heavy Hexagon Structural Bolts and for Heavy Semi-Finished Hexagon Nuts given in ANSI Standard B18.2.1 and B18.2.2, respect
41、ively. 568 HIGHWAY BRIDGES 11.3.2.4 11.3.2.4 Galvanized High-Strength Fasteners When fasteners are galvanized, they shall be specified to be hot-dip galvanized in accordance with AASHTO M 232 (ASTM A 153) Class C or, mechanically galvanized in accordance with AASHTO M 298 (ASTM B 695) Class 50. Bolt
42、s to be galvanized shall be eitherAASHT0 M 164 (ASTM A 325) Type 1 or Type 2 except that Type 2 bolts shall only be mechanically galvanized. Galvanized bolts shall be tension tested after galvanizing. Washers, nuts and bolts of any assembly shall be galvanized by the same process. The nuts should be
43、 overtapped to the minimum amount required for the fastener assembly, and shall be lu- bricated with a lubricant containing a visible dye so a vis- ual check can be made for the lubricant at the time of field installation. AASHTO M 253 (ASTM A 490) bolts shall not be galvanized. 11.3.2.6 Load Indica
44、tor Devices Load indicating devices may be used in conjunction with bolts, nuts, and washers specified in Article 11.3.2.1. Load indicating devices shall conform to the requirements of ASTM Specification for Compressible-Washer Qpe Direct Tension Indicators For Use with Structural Fasten- ers, ASTM
45、F 959, except as provided in the following paragraph. Subject to the approval of the Engineer, alternate design direct tension indicating devices may be used provided they satisfy the requirements of Article 11.5.6.4.6 or other requirements detailed in specifications provided by the manufacturer and
46、 subject to the approval of the Engineer. 11.3.3 Welded Stud Shear Connectors 11.3.3.1 Materials 11.3.2.5 Alternative Fasteners Other fasteners or fastener assemblies, such as those conforming to the requirements of ASTM F 1852, which meet the materials, manufacturing, and chemical compo- sition req
47、uirements of AASHTO M 164 (ASTM A 325) or AASHTO M 253 (ASTM A 490), and which meet the me- chanical property requirements of the same specification in full-sized tests, and which have body diameter and bearing areas under the head and nut, or their equivalent, not less than those provided by a bolt
48、 and nut of the same nominal dimensions prescribed in Article 11.3.2.3, may be used, subject to the approval of the Engineer. Such al- ternate fasteners may differ in other dimensions from those of the specified bolts and nuts. Subject to the approval of the Engineer, high-strength steel lock-pin an
49、d collar fasteners may be used as an alternate for high-strength bolts as shown on the plans. The shank and head of high-strength steel lock-pin and collar fasteners shall meet the requirements of Article 11.3.2.3. Each fastener shall provide a solid shank body of sufficient diameter to provide tensile and shear strength equivalent to or greater than that of the bolt specified, shall have a cold forged head on one end, of type and di- mensions as approved by the Engineer, a shank length suitable for material thickness fastened, locking grooves, breakneck groove and pull grooves
