494SECTION 407—STEEL AND OTHER METAL STRUCTURES
407.01 Description
This work shall consist of furnishing, fabricating, and erecting steel or other metal materials in accordance with these specifications and in conformity with the lines, grades, and dimensions shown on the plans or as established by the Engineer.
407.02 Materials
Steel shall conform to Section 226. Other metals shall conform to their respective sections of the Specifications.
407.03 Working Drawings
The Contractor shall submit to the Engineer working drawings of all structural steel, bearing assemblies, and anchorage devices to be used in the work on the contract for the Engineer’ s review and acceptance. Details shown on the working drawings shall conform to these specifications and the Structural Steel Design Section of the current AASHTO LRFD Bridge Design Specifications. In addition, primary stress units shall be detailed and identified by an individual piece mark. The Engineer’ s review of working drawings shall not relieve the Contractor of responsibility for errors on the drawings or deviations from the plans made by the Contractor unless such changes are preapproved in writing by the Engineer. Shop work shall not be performed until after the working drawings have been reviewed and accepted. The Contractor may, in writing, authorize the fabricator to act for the Contractor in matters relating to the working drawings in accordance with Section 105.10. If authority is granted by the Contractor to the fabricator, a copy of such authorization shall be provided to the Engineer. Working drawings shall specifically identify the composition and grade of metal or alloy of each piece other than steel conforming to ASTM A709, Grade 36. Pieces fabricated of different grades of steel shall not be given the same piece mark, even if they have identical dimensions and details.
407.04 Fabrication Procedures
Workmanship, finish, and fabrication tolerances shall conform to AISC standards and AWS welding codes except where the standards are in conflict with these specifications. Where AISC standards and AWS welding codes allow alternate methods of fabrication, the method used by the fabricator shall be that which produces the higher quality of workmanship and finish. Structural steel shall be fabricated in a shop certified by AISC under the Certification Program for Structural Steel Fabricators. Fabricators producing fracture-critical members, intermediate bridges, or advanced bridges shall be required to meet the supplemental requirements as appropriate. All structural steel fabrication not specifically covered under the Certification Program for Structural Steel Fabricators shall be fabricated in a shop certified by AISC under the Certification Program— Standard for Bridge and Highway Metal Component Manufacturers. All complex coating systems, defined as coatings which require special care in surface preparation, coating, component preparation, application control, curing, and in-process inspection, applied to 407.01 495structural steel shall be applied by a firm certified by AISC under the Certification Standard for Shop Application of Complex Protective Coating Systems. Fabrication and welding of structural steel bridge units shall conform to these specifications and AASHTO/AWS Bridge Welding Code D1.5. Structural components designated in the Contract as fracture-critical shall conform to the provisions of the AASHTO/AWS Bridge Welding Code D1.5, Section 12, Fracture Control Plan (FCP) for Non-redundant Members. Fabrication and welding of other structural and miscellaneous steel shall conform to these specifications and AWS Structural Welding Code D1.1 or AASHTO/AWS Bridge Welding Code D1.5, as appropriate. The Contractor shall give the Engineer at least 21 days advance notice of the beginning of contract work in the fabrication shop so that the Engineer can arrange for an inspection of the fabrication shop by a Department representative. Work shall not be performed in the shop on contract work before the Engineer has been notified. The Contractor shall furnish a complete mill analysis showing chemical and physical results from each heat of steel for all units prior to fabrication. Each piece of steel shall be properly identified as follows: Before cutting, pieces of steel other than steel conforming to ASTM A709, Grade 36, that are to be cut to smaller-sized pieces shall be legibly marked with the ASTM A6 specification identification color code or the material specification designation. The identification color code of the latest system adopted under ASTM A6 shall be used to identify material. If requested by the Engineer, the Contractor shall furnish an affidavit from the fabricator certifying that the fabricator has marked and maintained the identification of steel in accordance with these specifications throughout the fabrication operation.
a.Welds: Only welding or tack welding noted on the Plans shall be performed on structural steel, reinforcing steel, or aluminum units. Partial penetration welding shall not be allowed without the written permission of the Engineer. Preheat shall be applied in accordance with the applicable AWS code for the thickness and grade of material, but in no case shall be less than 70°F . Structural units shall not be used as a worktable. Welding on other work shall be completed before parts are installed on units. Groove welds in flange plates, cover plates, and longitudinal stiffeners shall be ground flush. Groove welds in legs of rigid frames, webs of exterior girders, and beams shall be ground flush on the exposed side. Cope holes shall not be filled. The perimeter of cope holes shall be ground smooth. Temporary erection bolt holes shall be filled with high-strength bolts and tightened in accordance with the specifications herein. Electroslag welding (ESW-NG) will not be allowed on Fracture Critical members. ESW-NG will only be allowed in other cases with written approval of the Engineer and in accordance with AWS D1.5. All ESW-NG shall be inspected in accordance with VTM 29 and VTM 30. Electrogas welding will not be allowed. Welds that do not conform to the specifications as determined by visual inspection or nondestructive testing shall be repaired, or if not repairable, removed and replaced by the Contractor by methods 407.04 496permitted in the specifications or the Engineer will reject the entire piece. The Engineer will re- inspect repaired or replaced welds in accordance with the applicable nondestructive testing method. The Contractor shall submit or shall have the fabricator submit to the Engineer a copy of the certificate of qualifications for each welder, welding operator, or tacker employed in the work. The Contractor shall also submit to the Engineer a certificate stating that the welder, welding operator, or tacker has not exceeded any period of 3 months since the date of qualification without performing satisfactory welding in the required process. The qualification certification shall state the name of the welder, operator, or tacker; name and title of the person who conducted the examination; type of specimens; position of welds; results of tests; and date of the examination. The qualification certifi - cation shall be made by a Department approved agency. Welds for reinforcing steel, including tack welds, shall conform to AWS D1.4. Welding of aluminum shall conform to AWS D1.2. Welds for tubular structures shall conform to AWS D1.1 for cyclically loaded tubular structures, unless using ESW-NG.
b.Straightening and Curving Rolled Beams and Plate Girders:
1.Straightening material: Rolled material shall be straightened before being laid off or worked. When straightening is required, the fabricator shall use methods that will not damage the metal. If straightening is performed by heating, heating shall be performed in accordance with
2.herein. The Engineer will reject sharp kinks or bends in the material.
2.Curving rolled beams and plate girders: The Contractor shall have the fabricator submit a detailed procedure for the method of heat curving beams or girders. Heat shall be applied so as to bring the steel to the temperature required for heat curving as rapidly as possible but not to more than 1200 degrees F , except in the case of steel conforming to ASTM A709 HPS 70W , which shall be no more than 1150 degrees F . The Engineer will reject the unit when any portion of a unit is heated to a temperature in excess of 1200 degrees F , or any ASTM A709 HPS 70W when steel is heated in excess of 1150 degrees F .
a.Sequence of operations: Units shall be cambered before heat curving and shall be heat curved in the fabrication shop before painting. Longitudinal stiffeners shall be heat curved or cut separately and then welded to the curved units. When cover plates are to be attached to the 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 more than 1,000 feet. For other rolled beams with cover plates, beams shall be heat curved before cover plates are attached. Cover plates may be either heat curved or cut separately and then welded to the curved beam.
b.Camber compensation: To compensate for the loss of camber of heat-curved units in service having a radius of 800 feet or less, additional camber shall be provided in the units. The amount of additional camber at the midlength of the unit shall be Ch for units 407.04 497having a radius less than 500 feet and 1/2 Ch for units having a radius from 500 feet to 800 feet. Ch shall be computed as follows: Ch = 0.02 L2Fy EY o where: L = the length, in inches, of the unit specified to be cambered Fy = the specified minimum yield point of the flange in kips per square inch E = the modulus of elasticity in kips per square inch Yo = the distance from the neutral axis to the extreme outer fiber in inches (maximum distance for nonsymmetrical sections). The additional camber, C'h , at any other point in the unit shall be computed as follows: C'h = C' x Ch C where: C = the camber specified at midlength in the design plans C' = the camber specified at any other point in the design plans. The additional camber provided shall be shown on the working drawings.
c.Type of heating: Where heat curving is permitted by the plans, plate girders and rolled beams may be curved by either continuous or V -type heating. Heat curving shall not be performed until camber conforms to the requirements of the specifications and plans.
1.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 uniform curvature.
2.V-type method: 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. Spacing and temperature shall be as required to obtain the required uniform curvature. Heating shall progress simultaneously along the outside surface of the top and bottom flange. When the flange thickness is 1 1/4 inches or greater, heat shall be applied simultaneously to the inside flange surface (surface that intersects with the web) and outside flange surface.
d.Position for heating: The unit may be heat curved with the web in the vertical or horizontal position. When curved in the vertical position, the unit shall be braced or supported so that the tendency of the unit to deflect laterally during the heat-curving process will not cause the unit to overturn. When curved in the horizontal position, the unit shall be properly supported to obtain a uniform curvature. The bending stress in the flanges attributable to the dead weight of the girder shall not exceed the allowable design stress. When the unit is positioned horizontally for heating, safety catch blocks shall be maintained at the midlength of the unit within 2 inches of the flanges at all times during the heating process.407.04 498The Engineer will reject any method of handling, supporting, or loading that may cause or causes the unit to distort permanently (yield without the application of heat).
e.Artificial cooling: The Engineer will not permit quenching to cool the steel. Cooling with dry compressed air will be permitted after the steel has naturally cooled to 600 degrees F .
f.Measurement of curvature: Prior to final acceptance of horizontal curvature, welding and heating operations shall have been satisfactorily completed and the unit cooled to a uniform temperature.
c.Camber: Rolled beams and plate girders shall be cambered in the amount indicated on the plans. Camber shall approximate a parabolic curve. Camber for rolled beams shall be obtained by heat-cambering methods. For plate girders, the web shall be cut to the prescribed camber with a suitable allowance for shrinkage attributable to cutting, welding, and heat curving. Tolerance for the specified camber of welded beams or girders before erection shall not exceed the greater of (A) or (B) where: (A) + 1/4 inch x Feet of test length (Not to exceed 3/4 inch) (B) + 1/8 inch x Feet from nearest end Tolerance for the specified camber of rolled beams as measured at midlength shall be: +1/8 inch x Feet of test length Camber shall be measured with the beam or girder laying on its side on a flat horizontal surface.
d.Bolt Holes: Bolt holes shall be punched, drilled, or reamed as specified herein. Holes shall not be flame cut or electrode cut. Finished holes shall be 1/16 inch larger than the nominal bolt size. Oversized holes will be permitted only with the permission of the Engineer or in accordance with Section 407.06(b). Finished holes shall be within 1/16 inch of the plan gage and match-mating holes, with no offset greater than 1/16 inch. The Engineer will reject holes varying more than 1/16 inch from the plan gage. Burrs shall be removed from holes.
1.Punched holes: The diameter of the die shall not exceed the diameter of the punch by more than 1/16 inch. Holes shall not be punched in structural carbon steel with a specified yield point of 36 ksi or less, thicker than 3/4 inch, or in high-strength structural steel with a specified yield point above 36 ksi, thicker than 5/8 inch. When these thicknesses are exceeded, holes shall be subdrilled and then reamed or drilled full size. Holes may be punched full size (1/16 inch larger than bolts) in secondary units or members and their connecting plates or angles. Holes shall be clean cut, without torn or ragged edges. 407.04 499The Contractor will not be permitted to punch full sized holes in structural members identified in Section 407.04(k)1 or in the Plans, Special Provisions, or elsewhere in the Contract as main (primary) members or units. Subpunched holes that are to be reamed shall be 3/16 inch smaller in diameter than the nominal bolt size. The location offset between subpunched holes assembled for reaming shall be not more than 1/8 inch.
2.Reamed and drilled holes: Holes shall be subdrilled and reamed to 1/16 inch larger than bolts. If numerically controlled drilling equipment is used, the Contractor may be required by means of check assemblies to demonstrate that this procedure can consistently produces holes that conform to the dimensions shown on the plans. Connections shall conform to this section. Shop assembly for numerically controlled drilled connections shall conform to AASHTO’ s Standard Specifications for Highway Bridges.
e.Cut Edges of Plates and Shapes: Cut edges shall have their corners rounded to a radius of 1/16 inch. Sheared edges of plates more than 5/8 inch in thickness shall be planed to a depth of 1/4 inch. Structural steel may be flame cut provided a smooth surface free from cracks and notches is achieved and that an accurate profile is achieved by the use of a mechanical guide. The Contractor will be allowed to free-hand cut only where approved by the Engineer.
f.Facing of Bearing Surfaces: 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 conform to the following surface roughness requirements as defined in ANSI B46.1: Member Roughness Height (microinches) Steel slabs 2,000 Heavy plates in contact in shoes to be welded 1,000 Milled ends of compression units, stiffeners, and fillers 500 Bridge rollers and rockers 250 Pins and pin holes 125 Sliding bearings 125
g.Bent Plates: The radius of bends shall be such that the plate does not crack. The minimum bend radii, measured to the concave face of the metal, shall be as follows: Thickness (t) (inches) Up to 1/2 Over 1/2 to 1 Over 1 to 1 1/2 Over 1 1/2 to 2 1/2 Over 2 1/2 to 4 2t 2 1/2 t 3t 3 1/2 t 4t Low-alloy steel more than 1/2 inch in thickness may require hot bending for small radii. If a shorter radius is essential, the plates shall be bent hot at a temperature of not more than specified in Section 407.04(b) 2. Before bending, the Contractor shall round the corners of the plate to a radius of 1/16 inch through - out the portion of the plate where the bending is to occur.407.04 500(h) Annealing and Stress Relieving: Structural units that are indicated on the Plans, the Specifi- cations, or elsewhere in the Contract to be annealed or normalized shall have finished machining, boring, and straightening done after heat treatment. The fabricator shall uniformly maintain temperatures throughout the furnace during heating and cooling cycles so that the temperature of any two points on the unit will not differ at any time by more than 100 degrees F . A record of each furnace charge shall identify the pieces in the charge and show the temperatures and schedule actually used. Proper instrumentation, including recording pyrometers, shall be provided for determining the temperature of units in the furnace at any time. The fabricator shall keep and maintain records of the treatment operation for inspection by the Engineer.
i.Pins and Rollers: Pins and rollers shall be forged or fabricated of cold-finished carbon steel shafting. In pins larger than 9 inches in diameter, a hole at least 2 inches in diameter shall be bored full length along the axis. Threads for pins shall conform to the American National Coarse Thread Series, Class 2, free fit, except that pin ends having a diameter of 1 3/8 inches or more shall be threaded six threads to the inch. Pinholes shall be bored at right angles with the axis of the unit. Boring holes in fabricated units shall be performed after welding is completed. The diameter of the pinhole shall not exceed that of the pin by more than 1/50 inch for pins 5 inches or less in diameter or by 1/32 inch for larger pins.
j.Stud Shear Connectors: The diameter of the connectors shall be 7/8 inch, and the length shall be at least 4 inches. Heads shall project at least 2 inches above the plane of the bottom of the deck slab and shall be 3 inches below the plane of the top of the deck slab. In determining the required length of the shear connectors, the computed dead-load deflection, vertical curve correction, and actual (measured) camber of the fabricated beam shall be taken into consideration. Studs 3/4 inch in diameter may be substituted for 7/8-inch studs, or vice versa, by making an adjustment in the pitch proportionally to the cross-sectional area of the studs with a spacing of not more than 24 inches. Studs shall be adjusted as necessary to provide clearance for bolts in bolted splices. The fabricator’ s shop plans shall show the location (spacing) and heights of the stud shear connectors regardless of whether they will be welded in the shop or in the field. Studs shall be end welded automatically or semi-automatically to the steel beams. The method and equipment used shall be as recommended by the manufacturer of the studs and must be preapproved by the Engineer. Studs to be field welded shall be welded after structural steel is erected and metal decking or other walking or working surface is in place; however, structural steel with shop-applied studs may be erected provided erection is performed in accordance with Section 107.17.
k.Shop Assembly: Assembly shall be in accordance with the following:
1.Holes for field connections and field splices in the following main units shall be drilled with units assembled or numerically controlled drilled. Holes shall not be punched full size in the following main units or their connecting plates and angles:
a.Girders and rolled beams.
b.Trusses, arches, and towers.
c.Bent and rigid frames.
d.Diaphragms, crossframes, or bracing attached to straight steel box girders or attached to curved rolled beams, curved I girders, or curved steel box girders.407.04 501 e. Any member designated on the plans or in other contract documents as “fracture critical.”
f.Any other main (primary) member(s) or unit(s) identified as such in the Plans, Special Provisions, or elsewhere in the Contract.
2.Holes for floor-beam and stringer-end connections shall be subpunched or subdrilled and reamed to a template or reamed while assembled. Templates used for connections on like parts shall be located so that the parts are identical and require no match marking.
3.Surfaces of metal in contact shall be cleaned before assembly. Parts shall be drawn together and securely clamped before drilling or reaming. Units shall be free from twists, bends, or other deformation.
4.Drift pins may be used only to bring parts into position. If any holes must be enlarged to admit bolts, the hole shall be reamed only to the extent permitted in these specifications.
5.Connecting parts assembled in the shop for the purpose of reaming holes shall be match marked. Miscellaneous parts that are not completely bolted in the shop shall be secured by partial bolting to prevent loss or damage in shipment and handling.
l.Inspection: The Contractor shall perform quality control inspection, including, but not limited to, visual inspection and nondestructive testing. Visual inspection shall be performed in accordance with VTM-33 by inspectors qualified in accordance with ANSI/AASHTO/AWS Bridge Welding Code D1.5 or other appropriate AWS welding code, as applicable. Radiographic and magnetic particle testing shall be performed in accordance with VTM-29 and VTM-31, respectively. Ultra - sonic testing, when specified, shall be performed in accordance with VTM- 30. Railroad structures and fracture-critical units shall be given radiographic and ultrasonic inspections in accordance with VTM-44. The Engineer reserves the right to perform quality assurance inspection. The Contractor shall provide and furnish a Type III field office in accordance with Section 514 for use in the Engineer’ s inspection of material and workmanship within the fabrication shop. In addition to the requirements specified therein, the Contractor shall provide telephone service by a direct access line, a telephone, and maintenance thereof. Costs for installation of the direct access line, the telephone, maintenance, and local service shall be borne by the Contractor. The cost for long-distance will be borne by the Department. The Engineer shall be allowed free access to the necessary parts of the work. One reinspection of corrective action taken on defective material or fabrication will be performed by the Department without cost to the Contractor; the cost of further reinspections shall be borne by the Contractor. The cost of any retests made necessary by the replacement of rejected welds shall be borne by the Contractor. When requested, the Contractor shall provide working space for radio - graphic examination of welds and shall make such space available for at least 6 hours per inspection visit.
407.05 Handling, Storing, and Shipping Materials
Materials and units shall be placed at least 4 inches above the ground on platforms, skids, or other supports. They shall be supported in such a manner that they will not be overstressed or become deformed or otherwise damaged. High-strength bolts, nuts, and washers shall be stored in identifiable original containers in protective storage subject to the approval of the Engineer. Materials shall be kept free from dirt, grease, and other foreign materials; protected from corrosion; and properly drained.407.05 502(a) Material Furnished by Others: If the Contract is for erection only, the Contractor shall check the material delivered against the shipping lists and promptly report to the Engineer, in writing, any shortage or damage. The Contractor shall be responsible for the loss of any material in the Contractor’ s care or for any damage incurred after the shipment is received.
b.Marking and Shipping: Each unit shall be identified with an erection mark, and an erection diagram shall be furnished. The Contractor shall furnish as many copies of shipping statements and erection diagrams as the Engineer may require. The weight of each unit shall be shown on the statements. Units having a weight more than 3 tons shall have the weight marked thereon. Structural units shall be loaded on trucks or cars in such a manner that they may be transported and unloaded at their destination without being excessively stressed, deformed, or damaged. Main structural units shall be supported at their bearings or at such other supports as may be approved or directed by the Engineer. Bolts of one length and diameter and loose nuts or washers of each size shall be packed separately. Pins; small parts; and packages of bolts, washers, and nuts shall be shipped in boxes, crates, kegs, or barrels. A list and description of the contained material shall be plainly marked on the outside of each shipping container.
407.06 Erection Procedures
If the Contract is for erection only, the Contractor will receive the materials designated for use in the finished structure, free of charges, at the place designated, loaded or unloaded as specified. The Contractor shall promptly unload material the Contractor is required to unload and shall be responsible for demurrage charges. Before starting the work of erection, the Contractor shall fully inform the Engineer as to the method proposed to be followed and the size or capacity, amount and type of equipment to be used, which shall be subject to the Engineer’ s approval. No work shall be started until such approval has been obtained. The approval of the Engineer shall not relieve the Contractor of the responsibility for ensuring the safety of the Contractor’ s methods or equipment or performing the work in accordance with the plans and these specifications. When new steel beams are connected to existing steel beams, the Contractor shall temporarily connect the diaphragms to the beams, in a manner to allow for the deflection of the new beams after placement of the deck slab concrete. After the deck slab concrete has cured, the Contractor shall connect the diaphragms as shown on the plans. The Contractor shall erect steel, remove temporary construction, and perform all work required to complete the structure(s) as specified in the Contract, including removing the old structure(s), if specified, in accordance with the plans and the specifications.
a.Field Welding: When erection includes field welding, field welding and inspection shall be per- formed in accordance with Section 407.04.
b.Misfits Field Assembly: Correction of misfits will be considered a legitimate part of erection provided corrective work is necessary on not more than 10 percent of the holes in a continuous group of 10 or more holes or 10-percent of the number of individual pieces with fewer than 10 holes.407.05 503Drift pins may be used only to bring parts into position. Misaligned holes shall be corrected, where allowed by the Engineer, by reaming. However, no hole shall be elongated in any separate part to more than 1/8 inch larger than the nominal bolt size when a reamer not more than 1/16 inch larger than the nominal bolt size is used. The misalignment of holes before reaming shall not be more than 1/8 inch. Necessary work for alignment and assembly exceeding these tolerances will be considered caused by shop errors and will be promptly reported to the responsible party. Damage resulting from handling or transportation shall be promptly reported to the Engineer. When the Contract provides for complete fabrication and erection, the Contractor shall be responsible for misfits and errors and shall make the necessary corrections or replacements. When the Contract is for erection only, the Engineer, with the cooperation of the Contractor, will keep a record of labor and material used, and the Contractor shall render, within 30 days, an itemized bill approved by the Engineer.
c.Assembly of Structural Connections Using High-Strength Bolts: Field connections shall be made with high-strength bolts 7/8 inch in diameter fabricated in accordance with ASTM A325 unless otherwise specified. The Engineer will give consideration to the substitution of adequately designed welded connections if requested in writing by the Contractor.
1.Bolts, nuts, and washers: Bolts, nuts, and washers shall conform to Section 226 and shall each be from one manufacturer on any one structure unless otherwise approved by the Engineer. In addition, each bolt, nut, and washer combination, when installed, shall be from the same rotational-capacity lot. Prior to installation, the Contractor shall perform a field rotational- capacity test on two nut, bolt, and washer assemblies for each diameter and length in accordance with Section 226.02(h)3. Bolts fabricated in accordance with ASTM A490 and galvanized bolts fabricated in accordance with ASTM A325 shall not be reused. Retightening previously tightened bolts, which may have been loosened by the tightening of adjacent bolts, shall not be considered a reuse. Other bolts may be reused only if approved by the Engineer. Threads of plain (uncoated) bolts shall be oily to the touch when installed. Galvanized nuts shall be lubricated by lubricant containing a visible dye. Threads of weathered or rusted bolts shall be cleaned of loose rust, scale, and debris and relubricated. Lubricant shall be as recom - mended by the fastener manufacturer.
2.Bolted parts: Bolted parts shall fit solidly together when assembled and shall not be separated by gaskets or any other interposed compressible material. Before assembly, connecting surfaces, including areas adjacent to the washers, shall be free from scale (except tight mill scale) and shall also be free of burrs, dirt, and other foreign material that will prevent solid seating of the parts. Surfaces for bolted splices in main units fabricated from weathering steel and joint surfaces for other connections, when required on the plans, shall be blast cleaned in accordance with Section 411.04(a) 5. The minimum area to be blast cleaned shall be 12 inches beyond the outermost row of bolts in the flanges and web and shall include the entire contact surfaces of the splice plates and filler plates. Contact surfaces shall be free from dirt, loose scale, burrs, oil, lacquer, and rust inhibitor.
3.Installation: Only as many fasteners as are anticipated to be installed and tightened during a work shift shall be taken from protected storage. Uninstalled fasteners not used shall be returned to protected storage at the end of the shift. Bolts shall be installed with a hardened washer under the nut or bolt head, whichever is the element turned in tightening.407.06 504When bolts fabricated in accordance with ASTM A490 are used with steel having yield points less than 40 kips per square inch, hardened washers shall be installed under the nut and bolt head. An approved tension-indicating device shall be at all job sites where high-strength fasteners are being installed and tightened. Bolt tensioning devices and complete bolt assemblies shall be tested with this device at the start of construction and as required during the installation proce - dure. The calibrating device shall be capable of indicating actual bolt tension within a tolerance of 2 percent. The manufacturer or an approved testing agency shall have checked the device for the accuracy specified herein within the previous 12 months. Record of calibration testing and certification shall be available to the Engineer if requested. When turn-of-nut or direct tension indicators are used, a representative sample of at least three complete bolt assemblies of each diameter, length, and grade shall be tested. For short grip bolts, direct tension indicators with solid plates may be used to perform the required testing. However, the direct tension indicator shall be checked with a longer grip bolt in the approved tension-indicating device prior to testing with short grip bolts. A flat washer may be used when the surface adjacent to the bolt head or nut does not have a slope of more than 1:20 with respect to a plane normal to the bolt axis. Where an outer face of the bolted parts has a slope of more than 1:20 with respect to a plane normal to the bolt axis, a smooth beveled washer shall be used to compensate for the lack of parallelism. The threaded ends of bolts shall be placed on the inside, where practicable, for protection from weather. The length of bolts shall be such that the end of the bolt will be flush with or outside the face of the nut when completely installed without overtensioning the bolt. Fasteners shall be tightened to provide, when all fasteners in the connection are tight, at least the minimum bolt tensions shown in Table lV -3 for the size of the fastener used. Tightening shall be performed by the turn-of-nut method or by the use of a direct tension indicator using a load indicator washer. Power wrenches, if used, shall be of adequate capacity and sufficiently supplied with air to perform the required tightening of each bolt in approximately 10 seconds. If required because of bolt-entering and wrench-operation clearances, tightening by either procedure may be done by turning the bolt while the nut is prevented from rotating provided both the head and nut bear against surfaces having slopes not greater than 1:20.407.06 Required Min. Bolt Tension (lb.) Bolt Size ASTM A 325 Bolts ASTM A 490 Bolts 1/2 12,000 15,000 5/8 19,000 24,000 3/4 28,000 35,000 7/8 39,000 49,000 1 51,000 64,000 1 1/8 56,000 80,000 1 1/4 71,000 102,000 1 3/8 85,000 121,000 1 1/2 103,000 148,000TABLE IV-3 Bolt Tension 505The required minimum bolt tension is equal to 70 percent of specified minimum tensile strengths of bolts rounded to the nearest kip as specified in ASTM A325 and ASTM A490. Snug tight is defined as the tightness attained when a power wrench begins to impact solidly or when the bolts are firmly hand tightened with a spud wrench such that the complete area of the connecting surfaces are brought into firm contact with each other. Snug tightening shall progress systematically from the most rigid part of the connection to the free edges, and then the bolts of the connection shall be retightened in a similar systematic manner as necessary until all bolts are simultaneously snug tight and the connection is fully compacted.
a.Turn-of-nut tightening: Turn of the nut method shall not be used for tightening high- strength bolts. This prohibition can only be waived by written approval of the District Bridge Engineer or if specifically required by the Contract. Request to use turn of the nut method in lieu of Direct Tension Indicator (DTI) washers shall be accompanied by an explanation as to why use of this method is in the best interest of the Department. When the turn-of-nut method for tightening high-strength bolts is approved for use, bolts shall be installed in all holes and tightened to a snug tight condition to ensure that all parts of the joint are brought into contact with each other. Bolts shall be given a suitable match- mark and tightened additionally by the applicable amount of nut rotation specified in Table IV -4, progressing systematically from the most rigid part of the joint to its free edges. During this operation, there shall be no rotation of the part not turned by the wrench. Nut rotation is relative to bolt, regardless of the element (nut or bolt) being turned. For bolts installed by 1/2 turn and less, the tolerance is minus 0 plus 30 degrees; for bolts installed by 2/3 turn and more, the tolerance is minus 0 plus 45 degrees.
b.Direct Tension Indicators (DTI): Direct tension indicator washers shall be used for all high strength bolts, and installation shall be in accordance with Section 407.06(c)3; however, the indicator washer shall not be considered a substitute for the required hardened washer under the turned element. The indicator washer may be considered a substitute for the hardened washer required under the unturned element when bolts conforming to ASTM A490 are used with steel conforming to ASTM A709, Grade 36. Direct tension-indicator washers shall not be painted or coated with any epoxy or similar material prior to installation. The normal installation shall consist of the load indicator washer being placed under the unturned bolt head or unturned nut. However, if conditions 407.06 Disposition of Outer Faces of Bolted Parts One Face Normal to Both Faces Sloped Bolt Length Measured Bolt Axis and Other Not More Than From Underside of Both Faces Face Sloped Not 1:20 From Normal Head to Extreme Normal to More Than 1:20 (Bevel to Bolt Axis (Bevel End of Point Bolt axis Washer Not Used) Washers Not Used) Up to and including 1/3 turn 1/2 turn 2/3 turn 4 diameters More than 4 but not 1/2 turn 2/3 turn 5/6 turn more than 8 diameters More than 8 but not 2/3 turn 5/6 turn 1 turn more than 12 diametersTABLE IV-4 Nut Rotation From Snug Tight Condition 506require installation under the turned bolt portion, a hardened flat washer or nut face wash - er shall be fitted against the tension-indicating protrusions. Tension-indicating washers shall not be substituted for the hardened washers required with short-slotted or oversized holes but may be used in conjunction with them. The initial installation shall be to a snug tight condition, after which final tightening shall be performed by progressing systematically from the most rigid part of the connection to its free edges until the tension indicators on all bolts are closed to at least the required gap. The required gap shall be 0.015 inch or less between the indicator and the underside of the bolt head or nut when no washer is used with the indicator. If a hardened flat washer is used, the required gap shall be 0.010 inch or less between the indicator and the hardened flat washer. If the indication gap is closed completely, do not continue with additional tightening.
4.Inspection: The Engineer will observe the installation and tightening of bolts to determine that the selected tightening procedure is properly used and will determine that all bolts are appropriately tightened.
a.Inspection of installations using tension-indicating washers will normally be accom- plished by checking the residual gap with a metal feeler gage. Installations will be considered satisfactory if the average gap per bolt installation does not exceed 0.012 inch for a tension-indicating washer installed under the bolt head or 0.010 inch for a tension-indicating washer installed in conjunction with a hardened, flat washer or, if the gap has been reduced to zero, at any point around the indicator. The Engineer may verify by calibrated torque wrench that the work conforms to Table IV -3 regardless of the method of installation.
b.Turn of the Nut Method: When the Engineer approves the turn of the nut method for use, the Contractor, in the presence of the Engineer, shall use an inspection wrench to inspect the tightened bolts. No fewer than three typical bolts from the lot to be installed having a length representative of bolts used in the structure shall be placed individually in a cal - ibration device capable of indicating bolt tension at least once each working day. There shall be a washer under the part turned in tightening each bolt if washers are so used on the structure. If no washer is used, the material abutting the part turned shall be of the same specification as that used on the structure. When the inspection wrench is a torque wrench, each calibration test bolt shall be tightened in the calibration device to the minimum tension specified for its size in Table lV -3. The inspection wrench shall then be applied to the tightened bolt, and the torque necessary to turn the nut or bolt head 5 degrees (approximately 1 inch at 12-inch radius) in the tightening direction shall be determined. The average torque measured in the tests of three bolts shall be taken as the job-inspection torque. The torque wrench shall be a dial torque wrench and shall have been checked for accuracy within 1 year of its current use by the manufacturer or an approved testing agency. Bolts that have been tightened in the structure shall be inspected in the presence of the Engineer by applying, in the tightening direction, the inspection wrench and its job- inspection torque to 10 percent of the bolts but not fewer than two bolts selected at random in each connection. If no nut or bolt head is turned by this application of the job-inspection 407.06 507torque, the connection will be accepted as properly tightened. If any nut or bolt head is turned by the application of the job-inspection torque, this torque shall be applied to all bolts in the connection. Bolts whose nut or head is turned by the job-inspection torque shall be retightened and reinspected, or all the bolts in the connection may be retightened and the connection resubmitted for the specified inspection. A written record of the inspection results, indicating the location, test dates, and the results of each inspection shall be submitted to the Engineer as a condition for payment when the turn of the nut method is used.
d.Abutting Joints: Abutting joints in compression units and in tension units where so shown on the plans shall be faced and brought to an even bearing. Where joints are not faced, the opening shall not be more than 3/8 inch.
e.Alignment at Bearings and Transverse Connections: Beam ends, bearing stiffeners, and webs of girders and rolled structural shapes and other beam sections shall be vertical. Diaphragms or cross struts composed of channel sections not attached to bearing stiffeners may be fitted with the planes of their webs perpendicular to the planes of the flanges of longitudinal beams on gradients provided the channel flanges are turned to the downgrade side where practicable. Rolled beams and plate girders and their bearing assemblies shall be fabricated so that their bottom bearing surfaces lie in horizontal planes when in their erected positions. Steel plates for use with flexible bearing pads shall be beveled to conform to this requirement.
f.Falsework: Falsework shall be designed, constructed, and maintained for the loads that will rest upon it. The Contractor shall prepare and submit to the Engineer, for review and acceptance, plans for falsework or for changes to an existing structure necessary for performing the work and maintaining traffic. The Department’ s review of the Contractor’ s plans shall not relieve the Contrac - tor of any responsibility relative to safely performing the work. The Contractor shall have a Professional Engineer holding a valid license to practice engineering in the Commonwealth of Virginia inspect the completed falsework assembly supporting a bridge superstructure prior to placing loads. The Professional Engineer shall provide a certification based upon visual inspection of the completed falsework assembly that the falsework assembly conforms to the approved working drawings. However, such certification shall not require an exhaustive in - spection or testing or make the Professional Engineer liable for any deficiencies in workmanship or materials by the Contractor or for such conditions that cannot be ascertained from a visual in - spection.
g.Straightening Material in the Field: Straightening plates and angles or other shapes shall be done by methods that will not produce fracture or damage. Metal shall not be heated unless permitted by the Engineer, in which case the heating shall not exceed the temperatures specified in Section 407.04(b)2 as measured by temperature-indicating crayons or other approved means. After heating, the metal shall be cooled naturally. The surface of the metal shall be carefully inspected for evidence of fracture following straightening of the shape. If damage is caused by the Contractor, the cost of inspection shall be borne by the Contractor. Any damage attributable to the Contractor will be handled in accordance with Section 108.09(a).407.06 508(h) Assembling Steel: Bearing surfaces that will be in permanent contact in the finished structure shall be cleaned before units are assembled. Permanent bolts in splices of butt joints of compression units and permanent bolts in railings shall not be tightened until blocking and falsework have been removed. Immediately after erection, splices, and field connections shall have at least one-half of the holes filled with bolts or cylindrical erection pins, of which at least one-half of those connections shall be bolts. Bolts shall be placed in such a manner that they are evenly distributed throughout the spliced connection. Splices and connections carrying traffic during erection shall have holes filled with high-strength bolts that have been tensioned and checked prior to opening the structure to traffic. Erection bolts shall be of the same nominal diameter as the high-strength bolts, and cylindrical erection pins shall be 1/32 inch larger.
i.Finishing: Unpainted weathering steel units shall be abrasive blast cleaned in the shop after fabrication. Abrasive blast cleaning shall conform to SSPC-SP6/NACE No. 3, Commercial Blast Cleaning. Upon completion of erection and concrete work, the fascia of exterior beams and girders of unpainted weathering steel shall be cleaned in accordance with Section 411.04(a) 3. Wherever a depressed area is formed where water can be trapped or held, such as the juncture be - tween a beam or girder web and splice plate on a bottom flange, the area shall be completely sealed with polyurethane, or other approved sealant, conforming to FS TT-S-00230C, Type II, Class A, prior to painting. When the sealant is used in conjunction with weathering steel, the sealant shall be integrally pigmented to a dark bronze color. Weathering steel shall be cleaned and coated in accordance with Section 411.
j.Protective Coatings: Non-stainless ferrous metal surfaces shall be cleaned and painted in accor- dance with Section 411. Galvanizing shall conform to Section 233. When new steel beams are connected to existing steel beams, the Contractor shall temporarily con - nect the diaphragms to the beams in a manner to allow for the deflection of the new beams after placement of the deck slab concrete. After the deck slab concrete has cured, the Contractor shall connect the diaphragms as shown on the plans.
407.07 Measurement and Payment
Structural steel, including beams, girders, and miscellaneous steel will be paid for at the contract lump sum price or, when specified, in pounds of the specified metal in the fabricated structure, including bolts shipped, as weighed on a shop scale. However, any weight more than 1.5 percent above the computed weight for the entire structure will not be included for payment. The weight of erection bolts, field paint, boxes, crates, and other containers used for packing and materials used for supporting units during transport will not be included. In contracts having a pay item for structural steel, structural steel components, including shear connectors, bearing plates, bearing assemblies and pads, anchorages, expansion joints, bolts, and pedestals, whether embedded in concrete or not, and other metals or materials shall be included in the price for structural steel unless paid for as a separate pay item(s). Prices for structural steel shall include furnishing, fabricating, galvanizing, transporting, storing, erecting, and field painting. Prices for structural steel shall also include welding where required, costs for services of certified welding inspectors, and costs for the services of non-destructive testing technicians where required.407.06 509If specified in the Contract or permitted by the Engineer, weights of specific metals may be computed, in which case the computations shall be made on the following basis:
a.The unit weights of metal shall be as follows: Material Lb./Cu Ft Aluminum, cast or wrought 173.0 Brass 536.0 Bronze, cast 536.0 Copper alloy 536.0 Copper, sheet 558.0 Iron, cast 445.0 Iron, malleable 470.0 Iron, wrought 487.0 Lead, sheet 707.0 Steel, cast, copper-bearing, carbon, 490.0 silicon, nickel, and stainless Zinc 450.0 Pay items and pay units for specific metals will be as specified in the contract.
b.The weight of rolled shapes and plates up to and including 36 inches in width shall be computed on the basis of their nominal weights and dimensions as shown on the approved working drawings, deducting for copes, cuts, and open holes except bolt holes. The allowed percentage of overrun in weight specified in AASHTO M 160 shall be added to the nominal weights of plates more than 36 inches in width.
c.The weight of high-strength bolt heads, nuts, and washers shall be included on the basis of the following: Diameter (in) Weight Per 100 (lbs.) 1/2 18 5/8 31 3/4 52 7/8 78 1 111 1 1/8 152 1 1/4 206 The weight of high-strength bolts includes the head, the nut, the projection of the bolt through the nut, and one flat washer per bolt.
d.The weight of castings shall be computed from the dimensions shown on the approved working drawings, deducting for open holes. To this weight shall be added 10 percent for fillets and overrun.
e.As an allowance for shop paint, 0.4 percent shall be added to the total computed weight of metal.
f.The weight of metal railing shall be included unless it is a separate pay item.407.07 510(g) Steel grid flooring will be measured and paid for in accordance with Section 409.
h.The weight of steel or brass shims required shall be included. Fabrication of structural steel, when a pay item, shall include fabricating; cleaning and shop painting structural units; bolts; nuts; washers; and transporting and storing units at the designated location. Erection of structural steel, when a pay item, shall include equipment and incidentals required to transport units from their designated storage location to the erection site, unloading and storing, erecting, cleaning, and field painting. The cost of testing unit(s) required by the specifications shall be included in the price for the structural unit(s). Payment will be made under: ———————————————————————————————— Pay Item Pay Unit———————————————————————————————— Structural steel (Type) Lump sum or Pound Fabrication of structural steel (Type) Lump sum Erection of structural steel (Type) Lump sum———————————————————————————————— SECTION 408—BEARING DEVICES AND ANCHORS
408.01 Description
This work shall consist of furnishing and installing bearing plates, pads, rockers, expansion devices, anchors, or other devices used in conjunction with bearings or anchorages at superstructure supports in accordance with these specifications and in conformity with the plans or as established by the Engineer.
408.02 Materials and Fabrication
a.Bearing material and bearing pads shall conform to Section 237 and those specified herein.
b.Metal plates, shapes, bolts, and bars shall be of structural steel conforming to Section 226 and those specified herein.
c.Metal parts shall be fabricated in accordance with Section 407.
d.Painting shall conform to Section 411.
e.Galvanizing shall be performed in accordance with Section 233.
408.03 Procedures
a.High-Load Multi-Rotational Bearings: High-load multi-rotational bearings including sole and masonry plates shall be any type shown on the plans and shall be provided by only one manufacturer.407.07
Source: Virginia Road and Bridge Specifications, 2020 Edition. Pages 522–537 of 1,065.