ITEM 441 STEEL STRUCTURES

Transcription

1 ITEM 441 STEEL STRUCTURES Description. This Item shall govern for the fabrication and erection of structural steel and other metals used for steel structures or steel portions of structures as shown on the plans and in accordance with this Item Materials. The metal used for the various portions of the structures shall conform to the requirements of Item 442, "Metal for Structures" General. (1) Qualification of Plant and Personnel. Bridge fabrication plants will be investigated by the Department for competency of the plant, equipment, organization, experience, knowledge, and personnel to produce quality work. Fabrication plants found to be in conformance with guidelines outlined in the AASHTO Standard Specifications for Highway Bridges will be approved by the Director of Materials and Tests. In addition, the contractor of bridge structures of major steel bridges (all bridge structures other than simple rolled beam bridges) shall possess a current Category III Certification from the American Institute of Steel Construction (AISC) Quality Certification Program. (2) Erection Drawings. All erection drawings shall be checked by the Contractor before submitting them for approval. The requirements for the Title Block stated in "Shop Drawings" shall also apply to Erection Drawings. Submission of five (5) sets of preliminary erection drawings and seven (7) sets of detailed erection plans shall be made to the Director of Bridges and Structures, Texas Department of Transportation, 125 East 11th Street, Austin, Texas, One (1) additional copy of detailed erection plans will be required if the structure is a railroad underpass. Additional sets may be required by the Engineer. (a) Preliminary Erection Drawings. For plate girder units, preliminary erection drawings showing the sequence of erection and the location of ground and air splices and supports shall be submitted to the Director of Bridges and Structures for approval prior to the submission of shop drawings. (b) Field Erection Drawings. Prior to field erection the Contractor shall prepare and submit for approval detailed erection plans, bearing the seal of a registered professional engineer, for plate girders (bolted or welded), trusses, and for all railroad underpass structures showing procedures, sequence of work, equipment to be used, falsework, adjacent structures loaded, etc. This detailed procedure shall follow the preliminary procedure previously submitted. Field erection plans for I-beam units will not be required unless specified on the plans. (3) Shop Drawings. The Contractor shall prepare and submit detailed shop drawings for each detail of the general plans requiring the use of structural steel, forgings, wrought iron, castings, or bearings. Shop drawings for plate girder units shall not be submitted before preliminary erection drawings are submitted for approval and will not be returned until the preliminary erection plan has been approved. Camber, sweep, and shop assembly drawings will be required. Values for camber (vertical curvature) and sweep (horizontal curvature) shall be detailed along the length of the girder section at the same locations shown on the contract plans. If not shown on the contract plans, values shall be detailed at a minimum spacing of 1/4 points. Shop assembly drawings (combination of two or more girder sections) shall be detailed at a minimum of 1/4 points for each girder section in the shop assembly. Members that are to be heat curved shall be noted on the shop drawings. All shop splices subject to tension or reversal of stresses shall be so noted on the shop drawings. Fracture critical members shall be identified on the shop drawings by the designation of "FCM". The drawings shall be prepared on sheets 22 by 34 inches or on 11 by 17 inch sheets, or full size drawings may be reduced to half-scale size, if they are completely clear and legible. The margin at the left end shall be 1-1/2 inches wide and the others 1/2 inch. Each sheet shall have a title block in the lower right-hand corner. The title shall include the sheet index data shown on the lower right-hand corner of the project plans, sheet numbering for the shop drawings, name of structure or stream, name of contractor of bridge structures and name of Contractor. Each sheet shall have a bill of material, including the Charpy V-Notch requirement for

2 each piece. The Contractor shall have the contractor of bridge structures check shop drawings before submitting the drawings for approval. Submission shall be made to the Director of Bridges and Structures, Texas Department of Transportation, 125 East 11th Street, Austin, Texas, Six (6) copies of shop drawings will be required, except that one (1) additional copy of each will be required for Railroad Underpass Structures. Additional sets may be required by the Engineer. Upon completion of fabrication, reproducible tracings of approved shop drawings, incorporating all changes, will be required for railroad underpasses only. The Contractor shall be responsible for the correctness and completeness of the drawings and for the fit of shop and field connections. Contract plans will indicate details of joints to be used with the shielded metal arc welding process. When the use of submerged arc welding, gas metal-arc welding or flux cored arc welding processes are anticipated, the shop drawings shall state the correct joint details and welding procedure number. (4) Welding and Fabrication Procedures. (a) Welding Procedures. When structural members are to be fabricated by welding, welding procedures shall be in accordance with the following welding codes: ANSI/AASHTO/AWS D1.5(D1.5) Bridge Welding Code for bridge structures ANSI/AWS/D1.1(D1.1) Structural Welding Code for all structures not considered bridges Welding procedures shall be submitted to the Director of Materials and Tests, l25 East 11th Street, Austin, Texas One copy of each required procedure shall be submitted on the applicable form. Upon approval, the welding procedures will be assigned Welding Procedure Numbers. The shop drawings shall include these numbers adjacent to the appropriate welding symbols. The same procedure, when proposed for subsequent projects, will not require resubmission unless required by the Fracture Control Plan. The applicable approved welding procedure specification for the welding being performed shall be posted on each welding machine. The approved welding procedure shall state the type and thickness of material; the welding process; welding position; electrode classification and size; type of flux; type, grade and flow of shielding gas; number, placement and sequence of weld passes; methods of cleaning; method of backgouging, if applicable; preheat and interpass temperatures; amps; volts; travel speed; joint detail; and other pertinent information required by the Engineer. (b) Galvanized Weldments. Where weldments are to be galvanized, the galvanizing procedure shall be approved prior to its use. The Fabricator shall prepare a test specimen with a minimum length of twelve (12) inches using the same base material, having the same joint configuration and using the welding procedure proposed for production work. This test specimen shall be cleaned and galvanized using the same conditions and procedure to be applied to the production galvanizing. After galvanizing, the test specimen shall be examined and there shall be no evidence of excessive buildup of zinc coating over the weld area. Evidence of excessive zinc coating build up will require modification of the galvanizing procedure. The zinc shall be removed from the weld area of the test specimen as described in ASTM A90 and the weld area visually examined. There shall be no evidence of loss of weld metal or any deterioration of the base metal due to the galvanizing and/or welding procedure. If evidence of deterioration or loss of weld metal is noted, the contractor shall modify the galvanizing and/or welding procedure as required and run a satisfactory retest on the modified procedures prior to production work.

3 When a galvanizing procedure is approved in combination with a welding procedure, the approved procedure may be used without requalification as long as the step by step galvanizing procedure and welding procedure, including base metal, welding process, amperage, voltage, speed of travel, and cleaning remain the same. At any time that problems develop during production galvanizing, a retest of the compatibility of the galvanizing and welding procedures as described above may be required. (c) Fabrication Procedures. When main structural members, as defined in Item 442, "Metal for Structures", are fabricated by welding or bolting, a fabrication procedure will be required from all contractors of bridge structures who are new to Department construction and may be required from any contractor of bridge structures when deemed necessary. A fabrication procedure shall include a list of equipment to be used, sequence of assembly, sequence and detail of connections made, special processes such as planing, facing, etc., detail of heat treating, heat curving, and heat straightening procedures and any other information concerning fabrication, as required by the Engineer. Contractors of bridge structures shall have an approved fabrication procedure for each type of structure (rolled beam with welded or bolted splices, plate girders with welded or bolted splices, trapezoidal steel girders with welded or bolted splices, steel box girders, steel plate girder bents, railroad thru-girder and plate girder, orthotropic deck segments, or other major bridge structure types) prior to starting fabrication. (5) Notice of Beginning Work. Contractors of steel structures shall give the Engineer notice prior to the beginning of work in the fabrication shop as follows: Shops in the State of Texas Shops in the Contiguous United States Shops in Foreign Countries 7 days 21 days 60 days No work shall be performed in the shop before the Engineer has authorized fabrication and returned approved shop drawings. Any purchases of material prior to fabrication authorization shall be at the Contractor's risk. (6) Inspection and Testing. Contractors of steel structures shall provide facilities, materials and equipment (temperature indicators, weld gauges, etc.) that are required for the inspection of material and workmanship in the shop. Unless otherwise authorized by the Engineer, contractors of bridge structures shall provide an office for use by the State, or the State's authorized representative, which is separate from that occupied by the Contractor's personnel. The office shall be located as near as possible to the work being performed. The office shall be a minimum of 150 square feet and be equipped with desks, chairs, filing cabinets, layout table, and plan rack. The office shall be weather tight, adequately lighted, heated, and air-conditioned. Rest room facilities shall be either incorporated or located nearby. The office and equipment shall be maintained so that it will continue to function properly for the intended use. The office shall be approved by the Engineer. The Contractor shall provide the Inspector with as many helpers and equipment as is needed to properly inspect the work. The Inspector shall be allowed free access to the necessary parts of the work. The Department will not perform quality control for the contractor of steel structures. Quality control shall be solely the responsibility of the Contractor of steel structures. The contractor of steel structures shall have a quality control staff qualified in accordance with Welding Codes D1.5 or D1.1, whichever is applicable. The quality control staff shall provide necessary inspection of all materials and workmanship prior to inspection by the Department. When fabrication of structural steel is accomplished outside of the contiguous 48 states, the additional cost of inspection will be in accordance with Article 6.2. The Inspector will have the authority to reject any material or work which does not conform to the requirements of the plans and specifications. In case of dispute, the Contractor may appeal to the Engineer, whose decision will be final.

4 Prior to beginning fabrication, the contractor of steel structures shall furnish the Engineer with two (2) copies of the completed material identification form with supporting mill test reports. These material identification forms will be furnished to the Contractor by the Department without charge. The mill test reports shall reflect: Specification to which material is produced. Heat number of material. Chemical and physical properties of the material required by the material specification. Impact test data when required. Grain size or statement that fine grain practice was used, when required. As material is shipped or placed in approved storage, the Contractor shall furnish the Engineer with two (2) copies of his shipping or storage invoice which shall reflect: Member piece mark identification and calculated weight per piece from the contract drawings. Number of pieces shipped or in storage. Total calculated weight for each invoice, per bid item. The shipping or storage invoice shall have a unique identification number. The acceptance of any material or finished members by the Inspector will not prohibit subsequent rejection if found damaged or defective. Rejected material shall be replaced promptly by the Contractor. (7) Welding. (a) All shop welding operations, processes, equipment, materials, qualifications of welders and welding procedures, workmanship, non- destructive testing, and inspection shall be in accordance with the ANSI/AASHTO/AWS D1.5 Bridge Welding Code (D1.5) or the ANSI/AWS/D1.1 Structural Welding Code (D1.1), except as amended by this Item. (b) Approved Electrodes and Flux-Electrode Combinations. Lists of approved electrodes and flux-electrode combinations will be maintained by the Director of Materials and Tests. All electrodes and flux-electrode combinations used on Department projects must be on the approved lists. For approval of electrodes or flux-electrode combinations, the Contractor or Manufacturer will submit to the Division of Materials and Tests, Austin, Texas, certified copies of all tests required by the applicable AWS Electrode and Electrode Flux Specification in accordance with the applicable Welding Code D1.5 or D Fabrication - General. (1) Handling and Storage of Materials. All material shall be handled in a manner that will prevent damage. If damage to material is caused by handling devices it shall be removed or repaired by acceptable means as outlined in ASTM A6, prior to subsequent fabrication steps. The handling of materials, fabrication, blocking of partially completed members and movement of completed members shall be done in such a manner that the safety of workmen and inspection personnel will not be impaired at any time. Stored material, either plain or fabricated, shall be placed above the ground on platforms, skids, or other supports and kept clean and properly drained. The material shall be kept free from dirt, grease, and other foreign matter and shall be protected from damaging corrosion or coating deterioration.

5 Structural steel shall be protected from salt water or other corrosive environments during either storage or transit. (2) Material Identification. The Contractor's system of assembly-marking individual pieces, and the issuance of cutting instructions to the shop (generally by cross-referencing of the assembly-marks shown on the shop drawings with the corresponding item covered on the mill purchase order) shall be such as to maintain identity of the original piece. report. The Contractor may furnish from stock material that can be identified by heat number and mill test Structural steel for bridge main members shall be identified by color coding and mill identification numbers (heat numbers). All other structural steel may be identified by color code only. Loss of color code marking on any piece, with no other positive identification, or loss of heat number identification on any main member piece, will require testing to establish acceptability to the satisfaction of the Engineer. Testing shall be performed by a commercial agency at the Contractor's expense. (a) Color Coding. Each approved steel shall be identified by color code in accordance with ASTM A6. The color "white" shall be used for ASTM A36 steel. Color codes for steels not specified in ASTM A6 shall be submitted to the Engineer for approval. Color codes shall differentiate between various material toughness requirements (CVN), as well as, any other special physical requirements. Contractors of steel bridges shall submit for approval the color code system that is to be used in their shop. The appropriate color(s) shall be placed on the material upon entry into the shop and shall be carried on all pieces to final fabrication. (b) Transfer of Mill Identification Numbers (Heat Numbers). Pieces of steel for main members of bridge structures which are to be cut to smaller pieces shall, before cutting, have heat numbers transferred using either paint or low-stress stencils. (3) Workmanship. (a) Railroad Structures. For railroad underpass structures, shop workmanship shall be in accordance with Chapter 15 of the latest American Railway Engineering Association (A.R.E.A.) Specification, except that cleaning of faying surfaces of bolted connections shall be in accordance with Article (b) Tolerances. Sections. Fabrication and rolling tolerances for rolled shapes, plates, bars, wide flange sections and miscellaneous steel shall be in accordance with ASTM A6. Tolerances for fabricated girders shall be in accordance with Welding Code D1.5 and this Item. Rolled sections or fabricated sections of slightly different dimensions and weight than the standard sections shown will be acceptable, provided equal or greater Moment of Inertia and Section Modulus for the completed section are provided. Maximum deviation from flatness for webs of wide flange sections shall be the same as for built-up girders. Flanges of completed girders shall be free of kinks, short bends and waviness that depart from straightness or the specified camber by more than 1/8 inch in any ten (10) feet along the flange. I-beams and girders shall be fabricated with a tolerance not greater than the following:

6 The plane of the bearing area of beams and girders shall be perpendicular to the vertical axis of the beam within 1/16 inch. Correction of bearing areas of shoes, beams and girders to the above tolerances, shall be with heat and/or external pressure. Grinding or milling will be permitted if reduction of the required thickness of the member is not reduced by more than 1/16 inch. Box girders shall be fabricated with tolerances not exceeding the following: The plane of the bearings supporting the box girder shall be perpendicular to the vertical axis of the girder within 1/16 inch and true to each other, in that plane, to 1/16 inch. Each bearing shall be true to 1/32 inch across its entire width in the short direction. The plane of the beam supports on the box girder are bearing areas and shall be true to the box girder bearings to 1/16 inch in the short direction and true to the vertical axis of the nesting beams/girders to 1/16 inch. After fabrication, box girders shall be placed on their bearings to field grade, in the shop, and the plane of all bearing areas shall be verified by a method approved by the Engineer. Rolled material must be straight before being laid off or worked. Bearing Devices. Shoes shall be fabricated with a tolerance not greater than the following: The top bolster shall have the center 75 percent of the long dimension true to 1/32 inch, with the remainder true to 1/16 inch, and shall be true to 1/32 inch across its entire width in the short dimension. The bottom bolster shall be true to 1/16 inch across its diagonal. pin. For a pin and rocker type expansion shoe, the axis of rotation shall coincide with the central axis of the When the shoe is completely assembled and the top bolster is moved horizontally simulating the movement of the shoe in the finished structure, no point in the plane of the top bolster shall change elevation by more than 1/16 inch for the full possible travel of the rocker both ways from the neutral position, nor shall the top bolster change inclination with respect to the horizontal by more than one (1) degree during this same travel. (c) Pins, Pinholes, and Rockers. Pinholes shall be bored true to the specified diameter, smooth and straight, at right angles with the axis of the member, and parallel with each other, unless otherwise required. The diameter of the pinhole shall not exceed that of the pin by more than 1/50 inch for pins, five (5) inches or less in diameter, or 1/32 inch for larger pins. (d) Finish Requirements for Weathering Steel Structures in Unpainted Applications. All weathering steel shall be maintained at all levels of fabrication and construction as nearly as possible in the condition received from the mill. All shop welds shall be cleaned as necessary by power grinding or by blast cleaning to remove welding flux, slag and splatter prior to shipment from the plant. No marking will be permitted on the outside face of any fascia beam. (4) Cutting, Planing, Facing, and Fit of Members. Sheared edges of main member plates of more than 5/8 inch in thickness shall be planed to a depth of 1/4 inch.

7 Unless otherwise permitted by the plans, steel plates for main members shall be cut and fabricated so that the primary direction of rolling is parallel to the direction of the main tensile and/or compressive stresses. Steel and weld metal may be oxygen cut by the use of a mechanical guide, to a true profile and a smooth and regular surface free from cracks and notches is obtained. Hand cutting shall be done only where approved by the Engineer. Mill scale and extraneous material shall be removed from the cutting side of A514/A517 steel plates along the lines to be cut. Hand cutting of radii for beam copes and weld access holes is permitted if an acceptable profile and an acceptable finish is produced by grinding. Uses of other cutting processes shall require the approval of the Engineer prior to use. Oxygen gouging shall not be used on A514/A517 or A588 weathering steel. The surface finish of bearing and base plates and other bearing surfaces that are to come in contact with each other or with concrete shall meet the ANSI surface roughness requirements as defined in ANSI B46.1, Surface Roughness, Waviness and Lay, Part I: Steel Slabs ANSI 2000 Heavy plates in contact in shoes to be welded ANSI 1000 Milled ends to compression members, milled or ground ends of stiffeners and fillers ANSI 500 Bridge rollers and rockers ANSI 250 Pins and pin holes ANSI 125 In planing the surfaces of expansion bearings, the cut of the tool shall be in the direction of expansion. Finished machining, boring and straightening shall be subsequent to annealing or normalizing structural members. Normalizing and annealing (full annealing) shall be as defined in ASTM E44. The temperatures shall be maintained uniformly throughout the furnace during the heating and cooling so that the temperature at any points on the member will not differ by more than 100 F. When required by the plans, bridge shoes, pedestals or other parts which are built up by welding sections of plate together shall be stress relieved in accordance with Welding Code D1.5. (5) Bending. Bending shall be such that no cracking of the plate occurs. Minimum bend radii, measured to the concave face of the metal, are given in the following Table 1: Table 1 Thickness In Inches Up thru 1/2 Over 1/2 thru 1 Over 1- thru 1-1/2 Over 1-1/2 thru 2-1/2 Over 2-1/2 thru 4 All grades of structural steel in this specification 2 t 2-1/2 t 3 t 3-1/2 t 4 t

8 Allowance for springback of ASTM A514 and A517 steels shall be approximately three (3) times that for structural carbon steel. For break press forming, the lower die span shall be at least 16 times the plate thickness. Multiple hits are advisable. If a shorter radius is essential, the plates shall be bent hot at a temperature not greater than 1150 F, except for ASTM A514 and A517 steels. If ASTM A514 or A517 steel plates to be bent are heated to a temperature greater than 1125 F, the plates must be requenched and tempered in accordance with the producing mill's practice. Hot bending shall be such that no cracking of plate occurs. Before bending, the corners of the plate shall be rounded to a minimum radius of 1/16 inch throughout the portion of the plate at which the bending is to occur. (6) Repair of Defects Not Outlined in ANSI/AASHTO/AWS D1.5. The Contractor shall submit a repair proposal to the Engineer for approval. No repair work shall begin before approval is received from the Engineer. Repair procedures shall include sketches or full-size drawings as necessary to adequately describe the deficiency and proposed method of repair. These sketches will be dated, and signed by the Inspector, verifying the accuracy of the details. All repair work shall be in strict compliance with the approved repair procedure. (7) Straightening Bent Material. The straightening of plates, angles, other shapes, and built-up members, when permitted by the Engineer, shall be done by methods outlined in an approved procedure that will not produce fracture or other damage. Straightening of individual pieces shall be done prior to assembly into a built-up member. Distorted built-up members shall be straightened by mechanical means or, if approved by the Engineer, by the carefully planned and supervised application of a limited amount of localized heat. When heat is used in connection with mechanical force to straighten material, the mechanical force shall be applied, and held at a constant, prior to any application of heat. Heat straightening of A514/A517 steel members shall be done only under rigidly controlled procedures, each application subject to the approval of the Engineer. In no case shall the maximum temperature of the A514/A517 steel exceed 1125 F, nor shall the temperature exceed 950 F at the weld metal or within six (6) inches thereof. Heat shall not be applied directly on weld metal. In all other steels the temperature of the heated area shall not exceed 1150 F (a dull red). In all cases the temperature of the steel shall be controlled by approved temperature indicating devices, such as crayons, liquids, or bimetal thermometers. Kinks and short bends over 1/8 inch in any ten (10) feet will be cause for rejection of the material. Following the straightening of a bend or buckle, the surface of the metal will be inspected for evidence of fracture. Nondestructive testing may be required by the Engineer. (8) Camber. Girders shall be cambered before heat curving. The web shall be cut to the prescribed camber with suitable allowance for shrinkage due to cutting, welding, and heat curving. Camber for rolled beams may be obtained by heat-cambering methods approved by the Engineer. The heat-curving process may tend to change the vertical camber present before heating. (9) Heat Curving. Steels with a specified minimum yield strength greater than 50,000 psi shall not be heat-curved. Rolled beams and welded I-section plate girders of lower yield strengths may be heat-curved to obtain a horizontal curvature if all the following conditions are met. The Contractor shall submit a detailed procedure to the Engineer for approval prior to heat curving any beam or girder.

9 Minimum Radius of Curvature: For heat-curved beams and girders, the horizontal radius of curvature measured to the centerline of the girder web shall not be less than 150 feet and shall not be less than the larger of the values calculated (at any and all cross sections throughout the length of the girder) from the following two equations: R = 14bD (Fy).5 At R = 7500b FyA In these equations, Fy is the specified minimum yield point in kips per square inch of steel in the girder web, A is the ratio of the total cross-sectional area to the cross-sectional area of both flanges, b is the widest flange width in inches, D is the clear distance between flanges in inches, t is the web thickness in inches, and R is the radius in inches. In addition to the above requirements, the radius shall not be less than 1,000 feet when the flange thickness exceeds three (3) inches or the flange width exceeds 30 inches. The Contractor of steel bridges shall furnish calculations on the shop drawings substantiating that the above requirements have been met if members are to be heat curved. Type of Heating: Beams and girders may be curved by either continuous or V-type heating as approved by the Engineer. For the continuous method, a strip along the edge of the top and bottom flange shall be heated simultaneously; the strip shall be of sufficient width and temperature to obtain the required curvature. For the V-type heating, the top and bottom flanges shall be heated in truncated triangular or wedge-shaped areas having their base along the flange edge and spaced at regular intervals along each flange; the spacing and temperature shall be as required to obtain the required curvature, and heating shall progress along the top and bottom flange at approximately the same rate. For the V-type heating, the apex of the truncated triangular area applied to the inside flange surface (surfaces that intersect the web) shall terminate just before the juncture of the web and the flange is reached. To avoid unnecessary web distortion, heat shall not be applied directly to the web. When the radius of curvature is 1,000 feet or more, the apex of the truncated triangular heating pattern applied to the outside flange surface shall extend to the web. When the radius of curvature is less than 1,000 feet, the apex of the truncated triangular heating pattern applied to the outside flange surface shall extend past the web for a distance equal to 1/8 of the flange or three (3) inches, whichever is less. The truncated triangular pattern shall have an included angle of approximately 15 to 30 degrees, but the base of the triangle shall not exceed ten (10) inches. Variations in the patterns prescribed above may be made with approval of the Engineer. The flange edges to be heated are those that will be on the inside of the horizontal curve after cooling. Heating both flange surfaces is mandatory only when the flange thickness is 1-1/4 inches or greater, in which case both surfaces shall be heated simultaneously. Temperature: The heat-curving operation shall be conducted in such a manner that the temperature of the steel does not exceed 1150 F as measured by temperature indicating crayons or other approved methods. The heated member shall not be artificially cooled. Position for Heating: The girder may be heat-curved with the web in either a vertical or a horizontal position. When curved in the vertical position, the girder must be braced or supported to prevent overturning. When curved in the horizontal position, the girder must be supported near its ends and at intermediate points, if required, to obtain a uniform curvature. The bending stress in the flanges due to the dead weight of the girder must not exceed 0.5 of the specified minimum yield strength. When the girder is positioned horizontally for heating, intermediate safety catch blocks must be maintained at the midlength of the girder within two (2) inches of the flanges at all times during the heating process to guard against a sudden sag due to plastic flange buckling.

10 Sequence of Operations: The girder shall be heat-curved in the fabrication shop before it is painted. The heat curving operation may be conducted either before or after the required welding of intermediate stiffeners to web only is completed. Flange to stiffener connections shall be welded after heat curving has been completed. However, unless provisions are made for girder shrinkage, connection plates, diafram stiffeners and bearing stiffeners shall be located and attached after heat curving. If longitudinal stiffeners are required, they shall be heat-curved or oxygen-cut separately and then welded to the curved girder. When cover plates are to be attached to rolled beams, they may be attached before heat curving if the total thickness of one flange and cover plate is less than 2-1/2 inches and the radius of curvature is greater than 1,000 feet. For other rolled beams with cover plates, the beams must be heat-curved before the cover plates are attached; cover plates must be either heat curved or oxygen-cut separately and then welded to the curved beam Fabrication of Bolted Structures. High-strength bolts and bolting shall be in accordance with Item 447, "Structural Bolting". (1) Pitch and Edge Distance of Bolts. Pitch and edge distance not shown on the plans shall be in accordance with the latest edition of AASHTO Standard and Interim Specifications for Highway Bridges. (2) Bolt Holes and Preparation of Holes for Bolting. All holes shall be either punched, drilled, subpunched and reamed, or subdrilled and reamed 1/16 inch larger than the nominal diameter of the bolt. The following acceptable substitutes may be used at the Contractor's option: Requirement Reaming with parts assembled Subpunching 3/16 in. less dia. than that of the finished hole Subpunching Punching full size Acceptable Substitute Drilling full size with parts assembled or, if approved by the Engineer, drilling full size without assembly, provided the drilling is done by suitable numerically controlled (n/c) drilling equipment, subject to the specific limitations contained in Section (2) (c). Subpunching 1/4 in. less dia. than that of the finished hole. Subdrilling. Drilling full size or subpunching and reaming to size with or without all parts assembled. Holes in vertical load carrying connections and field splices of main members such as trusses, arches, plate girders, continuous beam spans, floor beams, stringers, bents, tower, field bolted diaphragms for curved plate girder units, field bolted diaphragms for railroad structures and rigid frames shall be prepared with parts assembled and either subpunched and reamed or subdrilled and reamed, or drilled full size. Holes for shop fasteners in floor beam end connections and stringer end connections may be subpunched and reamed to a steel template of not less than one inch thickness or reamed while assembled.

11 Field connections for secondary members such as diaframs, lateral bracing and sway bracing may be punched full size unless prohibited below. (a) Punched Holes. Unless prohibited above, members containing not more than five (5) thicknesses of material may be punched full size providing no material is thicker than 3/4 inch for High Yield Carbon (HYC), 5/8 inch for High Strength (HS) or 1/2 inch for Extra High Strength (XHS). The die diameter shall not exceed that of the punch by more than 1/16 inch. Holes shall be clear cut without torn or ragged edges. (b) Subpunched or Subdrilled Holes. Holes shall be subpunched or subdrilled 3/16 inch smaller than the nominal size of the bolt. (c) Reaming and Drilling Holes. Reamed or drilled holes shall be cylindrical and perpendicular to the member. Reaming and drilling shall be done with twist drills guided by mechanical means unless otherwise approved by the Engineer. Reaming and full-size drilling shall be done using a template, or while the connection is assembled. Full-size drilling may be done using Numerically Controlled (N/C) drilling equipment when approved by the Engineer. When the reaming or drilling is done while the connection is assembled, the contact surfaces of the connection parts shall be thoroughly cleaned. The connecting parts shall be held securely, without the use of welds, during hole preparation and the pieces shall be matchmarked prior to disassembly. Match marking will be done using low stress stencils. Following matchmarking, assembled pieces shall be taken apart and all burrs or shavings removed. Reaming or drilling through a steel template shall be done after the template has been accurately located as to position and angle and firmly bolted in place. All steel templates shall have hardened steel bushings in holes accurately dimensioned from the centerlines of the connection as inscribed on the template. The centerlines shall be used in accurately locating the template from the milled or scribed ends of the members. Templates used for reaming matching members, or the opposite faces of a single member, shall be exact duplicates. Templates for connections on like parts or members shall be accurately located so that the parts or members are duplicates and require no matchmarking. When N/C equipment is used, the contractor of bridge structures shall submit to the Engineer for approval the proposed procedures to accomplish the work from initial drilling or punching through check assembly. These procedures shall include the specific members to be N/C drilled or punched, sizes of the holes, location of common index and other reference points, check assemblies, and all other pertinent information. Holes drilled or punched by N/C equipment shall be drilled or punched either through individual pieces, or multiple pieces held tightly together. (3) Accuracy of Holes. Holes not more than 1/32 inch larger in diameter than that specified are acceptable. Slotted holes which are produced by flame cutting or a combination of drilling or punching and flame cutting shall not be more than 1/32 inch greater in width nor 1/16 inch greater in length than specified. The flame cut surface shall be ground smooth. Slightly conical holes which naturally result from punching operations are acceptable provided they do not exceed the tolerances specified herein. a) Punched and Drilled Holes. All holes punched full-size, subpunched, or subdrilled, shall be so accurately positioned that after assembling (before any reaming is done) a cylindrical pin 1/8 inch smaller in diameter than the nominal size of the hole may be entered perpendicular to the face of the member, without drifting, in at least 75 percent of the adjoining holes in the same plane. All holes shall pass a pin 3/16 inch smaller in diameter than the nominal size of the hole. If these requirements are not fulfilled, the misfabricated pieces will be rejected. (b) Reamed and Drilled Holes. When holes are reamed or drilled, 85 percent of the holes in any adjoining group shall, after reaming and drilling, show no offset greater than 1/32 inch between adjacent thicknesses of metal.

12 (c) Misaligned Holes. Correction of misaligned holes may be accomplished by using a tapered reamer in conjunction with a template that is placed and held to force the reaming to the best center of holes for that group. (4) Preparation and Fit of Members. When shown on the plans, abutting joints shall be finished or milled and brought to an even bearing. Where joints are not finished or milled the openings shall not exceed 3/8 inch. Floor beams and girders with end connection angles shall be built to + 1/32 inch of the exact length back to back of connection angles. If end connections are faced, the finished thickness of the angles shall be not less than that shown on the shop drawings. Members to be spliced by high strength bolts shall be in proper alignment. The drifting done during assembling shall be only such as to bring the parts into position and not sufficient to enlarge the holes or distort the metal Fabrication of Welded Structures. (1) Welding. Electroslag and electrogas welding processes will not be allowed. All groove welded web and flange butt joints of main bridge members, other than rolled beams, shall be welded by the submerged arc process whenever practical. All submerged arc welding equipment shall have automatic guidance capable of maintaining the position of the arc and controlling the speed of travel; when once set by the operator no further major manipulation is needed. Small adjustments to compensate for acceptable plate waviness, acceptable tilt of flange, etc., will be acceptable. The use of hand held semiautomatic submerged arc welding for welding bridge members will not be allowed unless altered to provide automatic guidance. Magnetic particle (MT), radiographic (RT) and ultrasonic (UT) nondestructive testing and inspection will be as specified in Welding Code D1.5 for bridge structures and Welding Code D1.1 for all other welding. Unless otherwise shown on the plans, nondestructive testing required in the shop will be done by the Contractor and at his expense. This will include furnishing all materials, equipment, tools, labor and incidentals necessary to perform the required testing. The Department may require further testing as necessary in accordance with Article 5.9. MT, RT, and UT inspection shall be done in the presence of the Engineer or his authorized representative and at locations required by ANSI/AASHTO/AWS D1.5. The Engineer shall examine and interpret all test results of MT and RT inspection. UT inspection shall be performed by a qualified technician approved by the Engineer. The U.T. technician must hold a valid current American Society of Non- Destructive Testing (ASNT) Level II certification in Ultrasonic Inspection and pass a hands on test, which will be administered by the Division of Materials and Tests. Masking (i.e., edge blocks) shall be used at the end of butt welds being subjected to RT inspection. For shop welds on steel that has a specified yield strength over 65,000 psi, RT inspection shall be made on all flange and web splices. These welds shall be inspected not less than 48 hours after they are completed. UT inspection shall be made on full penetration corner and tee joints at the same frequency required by D1.5 or at other locations required by the Fracture Control Plan. Radiographs shall have a density of not less than 2.0 nor more than 3.2 with a density variation of not more than 0.5 and shall be confirmed by the radiographer.

13 Groove welds requiring repairs shall be retested by RT after repairs are made. All RT inspection and necessary repairs shall be done prior to assembly. All splices shall be RT inspected prior to main member assembly. RT inspection of designated welds, when shown on the plans, shall be in addition to the RT inspection required in this Item. (2) Preparation of Material for Welding. Dimensional tolerances, straightness and flatness of structural shapes and plates shall be in accordance with the appropriate Welding Code, D1.5 or D1.1, and this Item. Surfaces to be welded shall be smooth, uniform and free from fins, tears and other defects which would adversely affect the quality of the weld. Surfaces to be welded shall be free from loose scale, slag, rust, grease, or other material. Mill scale that withstands vigorous wire brushing or a light film of drying oil or rust inhibitive coating may remain. Finish of bevels of groove welds shall be milled or ground. Oxygen cut bevels without grinding will not be allowed. Surfaces within four (4) inches of a groove weld joining main stress carrying members and within two (2) inches of fillet welds joining diaframs or lateral bracing to stiffeners or gusset plates shall be free from paint and coated with linseed oil. Sheared plates for webs of built-up members shall be wide enough to allow for trimming of edges where built-in camber is required. Plates with rolled edges used for webs shall be trimmed by oxygen cutting. Preparation of edges by oxygen cutting shall be in accordance with Subarticle (4). The faying surfaces of the web and flange plates and the adjacent surfaces that are to be fillet welded shall have all mill scale removed by grinding prior to assembly and welding of web to flange. (3) Assembly of Parts. Extension bars shall be used on all groove welds and fillet welds of main members. Joint preparation and thickness of the extension bars shall be similar to the joint being welded. Minimum lengths of extension bars shall be one (1) inch for manual and semi- automatic processes and two (2) inches (longer if required to obtain satisfactory work) for automatic processes. For painted structures, joints not sealed by welds throughout their length shall fit close enough to exclude water after painting or shall be sealed with paintable silicone sealant prior to painting. All assemblies to be galvanized shall have all edges of tightly contacting surfaces completely sealed by welding. Except for galvanized structures and flange to web welds, fillet welds shall terminate approximately 1/4 inch from the end of the attachment unless otherwise noted on the contract drawings. Members to be welded shall be brought into correct alignment and held in position by clamping, welding, or tacking within the joint until the joint has been welded. A method to prevent cupping or warping of flanges must be used to disallow the cupping or warping beyond the tolerance of D1.5. These methods must be designed to not interfere with the operation or guidance of the automatic welding equipment. Temporary stiffeners used for jigs and/or warpage control shall not be tack welded to the flange material. Tacking to the web is permissible if the welds are at least 1/6 of the web depth away from the flange. The tack weld shall be removed by grinding flush with the parent metal prior to acceptance. Suitable allowance shall be made for shrinkage, and the joint shall never be restrained on both sides when welding.

14 Abutting parts to be joined by groove welds shall be aligned carefully. All shop groove welds in flange plates shall be ground smooth and flush with the base metal on all surfaces. These requirements shall apply to both parts of equal thickness and parts of unequal thickness. The surfaces shall be ground so that the radii at the points of transition will be four (4) inches minimum. Groove welds in web plates, except at locations of intersecting welds, need not be ground unless shown on the plans. Grinding shall be done in the direction of stress, and in a manner that keeps the metal below the blue brittle range (below 350 F). When groove welds are used to join materials of different thickness or width, there shall be a smooth transition between offset surfaces with a slope of not greater than one (1) in four (4) in thickness transition, and to the proper radii in the case of width transition (See Figures 1 and 2).

15 The member shall meet the combined tilt and warpage tolerances prior to the installation of stiffeners and the stiffeners shall be cut to fit acceptable flange tilt and cupping. Intermediate stiffeners within twelve (12) inches of a splice point shall be shipped tack welded in place. The welding shall be done in the field after the splice is made Shop Assembly. (1) General Shop Assembly for Bolted and Welded Field Connections. All fabrication, welding, and field splice preparation shall be complete before members are removed from shop assembly. Any deviation from this procedure will require the approval of the Engineer. All shop assemblies shall be in the unrestrained condition, free of external forces. Field connections of main members of trusses, arches, continuous beams, plate girders, bents, (box girders to girder connections) towers and rigid frames shall be preassembled prior to erection as necessary to verify the geometry of the completed structure or unit and to verify or prepare field splices. Attaining accurate geometry is the responsibility of the Contractor and he shall propose an appropriate method of preassembly for approval by the Engineer. The method and details of preassembly shall be consistent with the erection procedure shown on the erection plans and camber diagrams prepared by the Contractor and approved by the Engineer. As a minimum, the preassembly procedure shall consist of assembling three contiguous panels accurately adjusted for line and camber or span bent to bent. Assemblies consisting of less than three (3) panels shall require the approval of the Engineer. Successive assemblies shall consist of at least one section or panel of the previous assembly (repositioned if necessary and adequately pinned to assure accurate alignment) plus two (2) or more sections or panels added at the advancing end. At the option of the contractor of bridge structures, sequence of assembly may start from any location in the structure and proceed in one or both directions so long as the preceding requirements are satisfied. All bolted and welded field connections between bent cap girders and plate girders or between plate girders and floor beams shall have their fit verified by shop assembly. Horizontal curvature and vertical camber shall not be measured for final acceptance until all welding and heating operations are completed and the flanges have cooled to a uniform temperature. Horizontal curvature shall be checked with the girder web in the vertical position by measuring offsets from a string line or wire attached to both flanges or by using other suitable means, prior to final shop assembly. Camber will be checked with the girder web in the horizontal position. (2) Shop Assembly for Bolted Field Connections. Each shop assembly, including camber, alignment, accuracy of holes, and fit of milled joints, shall be approved by the Engineer before reaming is commenced or before a N/C or template drilled shop assembly is dismantled. All N/C or template drilled connections shall be performed prior to shop assembly and verified during shop assembly. The field connections of main members of trusses, arches, continuous beam spans, bents, towers (each face), plate girders, field connections of floor beams and stringers, field bolted diaphragms for curved plate girder units, and rigid frames shall be assembled in the shop with milled ends of compression members in full bearing, and then shall have all subsize holes reamed to the specified size while the connections are assembled or drilled full size while the connections are assembled. Parts not completely bolted in the shop shall be secured by temporary bolts to prevent damage in shipment and handling. In no case shall tack welding be used. Connecting parts in field connections shall be matchmarked (using low-stress stencils), and diagrams showing such marks shall be shown on the erection drawings. (3) End Preparation and Shop Assembly for Welded Field Connections. Prior to final shop assembly the ends of beams and girders shall be prepared in accordance with Figure 3 and the requirements herein or as shown on the plans. The centerline of the land of opposing web and flange bevels shall not deviate from each other by more than 1/16 inch.