Section 555 — Steel Structures
Description
555.01This work consists of constructing steel structures and the steel structure portions of composite structures.
Material
555.02Conform to the following Section: Structural metal 717
Construction Requirements
555.03Submittals. Submit the following according to Subsection 104.06 :
(a)Steel certifications. Provide copies of mill orders at the time orders are placed with the manufacturer. Provide certified mill test reports and production certifications before the start of fabrication using material covered by these reports. Include on certified mill test reports the chemical analyses and physical test results for each heat of steel used in the work and for steels with specified impact values, include the results of Charpy V - notch impact tests. Confirm on the test report that the material was so produced when fine -grain practice is specified. Provide production certifications instead of mill test reports for material that is not normally supplied with mill test reports and for items such as fills, minor gusset plates, and similar material when quantities are small and the material is taken from stock.
(b)Fabrication drawings. Show complete detailed dimensions and sizes of component parts of the structure and details of miscellaneous parts. Show the direction of plate rolling where specific orientation of plates is required. Show plate gi rder flanges and webs cut from plates so the long dimension of the girder parallels the rolling direction. Identify the type and grade of each piece that is to be made of steel other than AASHTO M 270, Grade 36 steel. Show assembly marks that are cross- referenced to the original pieces of mill steel and their certified mill test reports. Show shop- welded splice locations. Locate shop -welded splices to avoid points of maximum tensile or fatigue stress. Locate splices in webs at least 12 inches from shop splices, flange butt joints, or stiffeners. Additional nondestructive tests may be required on shop -welded splices.
(c)Erection drawings. Fully illustrate the proposed method of erection. Show details of falsework bents, bracing, guys, dead- men, lifting devices, and bridge member attachments. Show the erection sequence, crane and barge locations, crane capacities, lifting point locations, and bridge member masses. Show complete details for anticipated phases and erection conditions. If required during drawing revi ew, provide calculations showing that allowable stresses are not exceeded and that member capacities and final geometry are correct. Include drawings for temporary works according to Section 562.
(d)Camber diagram. Show the ca mber at each truss or arch rib panel point, at field splice locations, and at the specified span length fractions of continuous beams and girders or rigid frames. Show calculated cambers to be used in preassembly of the structure according to Subsection 555.14.
(e)Transportation drawings. Show support points, tie -downs, temporary stiffening trusses or beams, and other details needed to support and brace the member. Provide calculation sheets showing self-weight plus dynamic load allowance stresses induced by the loading and transportation procedure. Use dynamic load allowance stresses of at least 100 percent of the self -weight dead load stress. Do not allow fatigue stresses to exceed the constant -amplitude fatigue threshold for the appropriate categories. Verify computed girder stresses satisfy the AASHTO, LRFD Bridge Design Specifications . Ship and store members in the same orientation as the completed structure unless otherwise approved.
555.04Fabrication Notice. Give written notice at least 21 days before starting fabrication work. Do not manufacture material before notification and drawings are approved.
555.05Inspection. Ultrasonically inspect girder flanges before fabrication according to ASTM A578 and the following:
(a)Inspect after flanges are stripped from the master plate;
(b)Use ASTM A578, Supplementary Requirement S2.1 for acceptance standards; and
(c)Inspect flanges in the plant or warehouse where the flanges are stripped.
555.06Storing Material. Store structural material above the ground on platforms, skids, or other supports. Keep material free of dirt, grease, and other foreign matter. Protect from corrosion and stray electrical currents.
555.07Fabrication. Fabricate structural steel in a fabricating plant that is certified under the AISC, Quality Certification Program . Provide and fabricate fracture critical elements according to AASHTO, LRFD Bridge Design Specifications and Clause 12 of the AASHTO/AWS D1.5, Bridge Welding Code . Remove mill scale and foreign material from exterior surfaces of exterior girders of uncoated weathering steel by blast cleaning according to SSPC -SP6, Commercial Blast Cleaning . Then dry the surface and apply at least three uniform applications of water mist at 24 -hour intervals to ensure uniform weathering. Do not heat curve steel girders. Do not drill, cut, or weld portions of structural members unless shown in the plans or approved in writing. Coat structural steel according to Section 563. Fabricate bearing devices according to Section 564.
(a)Steel identification. Use a system of assembly -marking of individual pieces and cutting instructions (generally by cross referencing of the assembly -marks shown in the drawings with the corresponding item covered on the mill purchase order). Provide information to the shop that maintains the identity of the original piece. Identify material provided from stock by heat number and mill test report. During fabrication and before assembling members, show the specification of each piece of steel. Mark steel using steel die stamping or firmly attaching a substantial tag to pieces of steel which will be subject to fabricating operations which might obliterate paint marking before assembling into members. These fabrication operations include blast cleaning, galvanizing, heating for forming, or coating. Use low -stress type steel die stamps. Avoid impressions near edges of tensile- stressed plate members. Do not use die stamps on fracture -critical members. Provide an affidavit certifying the identification of steel has been maintained throughout the fabrication operation.
(b)Plates .
(1)Rolling direction. Cut and fabricate steel plates for main members and splice plates for flanges and main tension members, so that the primary direction of rolling is parallel to the direction of the principal tensile and compressive stresses.
(2)Plate cut edges.
(a)Edge planing. Remove sheared edges on plates thicker than 5⁄8 inch to a depth of ¼ inch beyond the original sheared edge or beyond re -entrant cuts produced by shearing. Fillet re - entrant cuts before cutting.
(1)Oxygen cutting. Perform oxygen cutting according to AASHTO/AWS D1.5, Bridge Welding Code .
(2)Visual inspection and repair of plate cut edges. Visually inspect and repair plate cut edges. Conform to AASHTO/AWS D1.5, Bridge Welding Code .
(b)Flange plates. Provide flange plates with either oxygen- cut edges that have ground corners chamfered at least ⅟ 16 inch or provide universal mill plates.
(c)Web plates. Use oxygen cutting to provide the prescribed camber in web plates of built- up beams and girders, box girders, and box arches. Cut sufficient extra camber into the webs to provide for camber losses due to welding and cutting.
(d)Truss members. Prepare longitudinal edges of plates in welded sections of truss web and chord members by oxygen cutting. Use grinding to chamfer the edges of the corners of plates at least ⅟ 16 inch if plates are not joined by welding.
(e)Stiffeners and connection plates. Sheared edges may be used on plate thicknesses up to ¾ inch for stiffeners and connection plates welded transverse to girder webs and flanges. Universal mill plate may be used for plate thicknesses up to 1 inch. Provide other stiffeners and connection plates with oxygen- cut edges.
(f)Lateral gusset plates. Bolted lateral gusset plates may be provided with sheared edges provided the thickness is less than or equal to ¾ inch. Oxygen cut, parallel to lines of stress, gusset plates and other connections wel ded parallel to lines of stress in tension members where the plate thickness exceeds ⅜ inch.
(g)Splice plates and gusset plates. Provide with oxygen- cut edges.
(h)Bent plates. Provide un-welded, load- carrying, rolled steel plates. Bend plates at right angles to the direction of rolling, except cold- bent ribs for orthotropic -deck bridges may be bent in the direction of rolling. Before bending, round the plate corners to a radius of ⅟ 16 inch throughout the portion of the plate where the bending occurs. Cold bend fr acture- critical steels and nonfracture -critical plates and bars. The minimum bending radius for plates bent perpendicular to the direction of rolling is 5 times the plate thickness, except for cross -frame or diaphragm connection plates up to ¾- inch thick, for which the bending radius is 1.5 times the plate thickness. Orient bend lines perpendicular to the direction of the final rolling of the plate where possible. For plates bent parallel to the direction of rolling, the minimum bending radius is increased to 7.5 times the plate thickness, except for web splice plates, fillers, gusset plates not serving as chord splices, connection plates, and web stiffeners. Hot bend steel members only if allowed in the plans. Hot bend the plates at a temperature less than 1200 °F, except for Grades HPS 70W and HPS 100W. Do not heat Grades HPS 70W and HPS 100W to a temperature greater than 1100 °F.
(c)Stiffener fit. Fabricate (mill, grind, or weld) girder end bearing stiffeners and concentrated load bearing stiffeners to provid e full bearing on the flanges to which the load is transmitted or received. Fabricate intermediate stiffeners to provide a tight fit against the compression flange.
(d)Abutting joints. Mill or saw cut abutting joints in truss and column compression members to obtain a square joint and uniform bearing. Other joints not required to be faced may have openings up to ⅜ inch.
(e)Bearing surface facing. Finish bearing surfaces as shown in Table 555-1 and American Society of Mechanical Engineers (ASME ) B46.1, Surface Texture (Surface Roughness, Waviness and Lay), Part I . Table 555-1
ASME Surface Roughness Values
Bearing Surface Surface
Roughness Value,
microinch Steel slabs 2000 Heavy plates in contact in shoes to be welded 1000 Milled ends of compression members, milled or ground ends of stiffeners & fillers 500 Bridge rollers & rockers 250 Pins & pin holes 125 Sliding bearings 125 Machine sliding bearings with a surface roughness greater than 75 microinches so the lay of the cut is parallel to the direction of movement. Fabricate bearing parts to provide uniform even contact with the adjacent bearing surface. Limit the maximum gap between bearing surfaces to 0.04 inch. Machine the base plate sliding surfaces if the plane a nd true base and sole plates exceed the surface roughness value shown in Table 555-1. Machine surfaces of fabricated assemblies only when heat treatment and fabrication on the assembly is complete.
(f)Straightening material. Straighten plates, angles, other shapes, and built -up members using methods that do not fracture or damage the metal when approved. Use mechanical means or a limited amount of localized heat when approved. Do not exceed the temperatures shown in Table 555-2 and control the heat application with temperature -indicating crayons, liquids, or bimetal thermometers. Remove external forces from the material to be straightened, except for the mechanical stress designed to be used in conjunction wit h the heat. Table 555-2
Maximum Straightening and
Stress Relieving Holding Temperatures
Material Maximum Temperature, °F Grades HPS 70W & HPS 100W 1100 Other Steels 1200
555.08Annealing and Stress Relieving. Normalize and anneal (full annealing) according to ASTM A941. Maintain uniform temperatures throughout the furnace during the heating and cooling so the temperature at no two points on the member differs by more than 100 °F. Record each furnace charge, identify the pieces in the charge, and show the temperatures and schedule used. Provide proper instruments including recording pyrometers for determining member temperatures. Provide records of the treatment operation for approval. Do not anneal or normalize Grade HPS 100W or HPS 70W s teel members without approval. See Table 555-2 for the maximum stress relieving holding temperature for these grades. Relieve stress from members (such as bridge shoes, pedestals, or other parts that are built -up by welding sectio ns of plate together) according to Subsection 4.4 of the AASHTO/AWS D1.5, Bridge Welding Code .
555.09Bolt Holes. Punch or drill bolt holes. If required below, either subpunch or subdrill holes 3⁄16 inch smaller than the nominal bolt diameter and after assembling ream or drill full size.
(a)Punched holes. Unless subpunching and reaming is required by Subsection 555.09(h) , punch material forming parts of a member composed of 5 thicknesses or less of metal if the material thickness is no greater than:
(1)¾ inch for Grade 36 steel;
(2)⅝ inch for Grade 50, 50W, 50S, and HPS 50W steel; or
(3)½ inch for Grade HPS 70W and HPS 100W steel. Punch holes ⅟ 16 inch larger than the nominal bolt diameter. Ream holes that require enlarging to admit bolts. Produce clean cut holes without torn or ragged edges.
(b)Reamed or drilled holes. Subdrill and ream or drill holes full- size where there are more than five thicknesses or where the main material is thicker than Subsections 555.09(a)(1) through (3) . Assemble and securely hold together connecting parts that are being reamed or drilled and match -mark before disassembling. Where practical, use twist drills, twist reamers, or roto -broach cutters directed by mechanical means. Ream or drill cylindrical holes ⅟ 16 inch larger than the nominal bolt diameter that are perpendicular to the member. Remove burrs on the outside surfaces.
(c)Accuracy of holes. Drilled or reamed holes may be up to ⅟ 32 inch larger than the true decimal equivalent of the nominal diameter of the drill or reamer. Punch ed holes may be slightly conical. Slotted holes produced by flame -cutting or a combination of drilling or punching and flame cutting, may be up to ⅟ 32 inch larger than the nominal width. Grind flame cut surfaces smooth to a maximum surface roughness of 1000 microinches.
(d)Accuracy of hole group before reaming . Punch, subpunch, or subdrill holes to allow a cylindrical pin 3⁄16 inch smaller in diameter than the nominal size of the punched hole can be inserted in holes after assembling (before reaming). In addition, produce at least 75 percent of the contiguous holes in the same plane such that a cylindrical pin ⅛ inch smaller in diameter than the nominal size of the punched hole can be inserted perpendicular to the face of the member without drifting.
(e)Accuracy of hole group after reaming. Use dimensioned steel templates with hardened steel bushings in the holes. Use connection centerlines when locating templates from the milled or scribed ends of members. Produce at least 85 percent of the holes in a contiguous group of holes with a maximum offset of ⅟ 32 inch between adjacent thicknesses of metal after reaming or drilling.
(f)Numerically -controlled drilled field connections. Drill or punch full -sized bolt holes in unassembled pieces and connections using numerically-controlled drilling or punching equipment.
(g)Holes for ribbed bolts, turned bolts, or other approved bearing -type bolts. Provide finished holes with a driving fit.
(h)Preparation of field connections. Drill full size holes through all thicknesses of material assembled in proper position for field connections and field splices. Do not punch full -size holes in longitudinal main load -carrying members, transverse floor beams, or components designated as fracture critical members. Other options include the following:
(1)Main members of trusses, arches, continuous beam spans, bents, towers (each face), plate girders, and rigid frame connections and splice holes. Subpunch or subdrill and ream while assembled or drill full size to a steel template.
(2)Rolled beam stringers con tinuous over floor beams or cross frames. Drill full -size holes for field splices unassembled to a steel template.
(3)Floor beam and stringer field end connection holes. Subpunch and ream while assembled or drill full size to a steel template.
(4)Cross frames, lateral bracing components, and the corresponding holes in connection plates between girders and cross frames or lateral components. Punch full- size holes. Locate, position, and firmly bolt the template in place when reaming or drilling full size field-connection holes through a steel template. Use duplicates of templates used for reaming matching members or the opposite faces of a single member. Locate templates used for connections on like parts or members so that the parts or members are duplicates and require no match- marking.
555.10Pins and Rollers.
(a)Fabricating pins and rollers. Fabricate straight and smooth pins and rollers without flaws. Forge and anneal pins and rollers or use cold- finished carbon steel shafting for diameters less than 9 inches. Slowly cool forged pins to a temperature below the critical range to prevent damage from rapid cooling. Bore a hole in the pin at least 2 inches in diameter full- length along the pin axis before annealing.
(b)Boring pin holes. Do not exceed the pin diameter by mo re than ⅟ 50 inch for pins 5 inches or less in diameter or exceed by more than ⅟ 32 inch for larger pins when boring pin holes. Bore pin holes smooth, straight, at right angles with the axis of the member, and parallel with each other. Produce the final surface using a finishing cut. Produce a maximum variation in the distance outside- to-outside of end holes in tension members and inside- to-inside of end holes in compression members of ⅟ 32 inch from that specified. Bore pin holes in built- up members after the member is assembled.
(c)Threads for bolts and pins. Conform to the ASME B1.1, Unified Inch Screw Threads (UN, UNR, and UNJ Thread Forms) , Class 2A for external threads and Class 2B for internal threads. Provide six threads per inch for pin ends with a di ameter of 1⅜ inches or greater.
555.11Eyebars. Provide eyebars that are straight and without twists. Limit the inclination of bars to the plane of the truss to a 0.5 percent slope. Locate pin holes on the centerline of the eyebar. Securely clamp eyebars that are to be placed side- by-side in the structure in the order they are to be placed on the pin. Bore the pin holes to the finished diameter from both ends or flame cut the pin holes at least 2 inches smaller than the finished pin diameter. Simul taneously cut the edges of eyebars that lie between the transverse centerline of their pin holes with two mechanically operated torches abreast of each other guided by a substantial template to prevent distortion of the plates. Use low -stress type steel die stamps to match -mark eyebars for shipment and erection. Locate stamps on the visible edge each member when the bars are nested in place on the structure.
555.12Assembly B olting. Clean metal contact surfaces. Assemble, securely pin, and draw together member parts. Drill, ream, and bolt the assembly. If necessary, take assembly apart to remove burrs and shavings produced by the operation. Assemble the members without twists, bends, and other deformation. Drift only enough to bring the parts into position without enlarging holes or distorting metal.
555.13Welded Connections. Conform to AASHTO/AWS D1.5, Bridge Welding Code . Install shear connector studs according to Chapter 9. Perform preproduction testing according to Subsection 9.7.1 and inspect installe d studs according to Subsection 9.8.
555.14Preassembly of Field Connections. Submit method and details of preassembly for approval. Preassemble field connections of truss, arch, continuous beam, plate girder, bent, tower, and rigid frame main members. Us e preassembly methods and details consistent with approved erection procedures and camber diagrams. Assemble girders and beams in their cambered (no load) condition. When members are assembled with webs vertical, support the members at intervals of 20 feet, or two -tenths of the span length, whichever is less. When the webs are horizontal, support intervals may be increased provided there is no noticeable deflection between points of support. Assemble trusses in full dead -load position unless the design of the structure provides for secondary stresses created by the fully cambered assembly. Start assembly from a location in the structure and proceed in one or both directions. Support trusses at each panel point. Preassemble at least three contiguous panels. F or successive assemblies, include at least one section or panel of the previous assembly plus two or more sections or panels added at the advancing end. For structures longer than 150 feet, make each assembly at least 150 feet long. Verify the geometry of the completed structure or unit. Verify or prepare field splices.
(a)Bolted connections. Where applicable, assemble major components with milled ends of compression members in full bearing. While assembled, ream subsized holes to the specified size.
(b)Check assembly. Make a check assembly for each major structural type of each project based on proposed order of erection, joints in bearings, special complex points, or similar considerations. Assemble at least three contiguous shop sections. For trusses, assemble members in at least three contiguous panels, but at least the number of panels associated with three contiguous chord lengths (such as the length between field splices). Other shop assemblies are not required. Obtain approval of each assembly before reaming holes or dismantling the assembly. Inaccurate camber, alignment, hole alignment, milled joint fit, or other problems may require additional check assemblies.
(c)Field -welded connections. Do not field weld connections unless specifically shown in the drawings. Verify the fit of members, including the proper space between abutting flanges, with the segment preassembled.
(d)Match marking. Match mark connecting parts preassembled in the shop to ensure proper fit in the field. Provide a diagram showing match- marks.
555.15Connections Using Unfinished or Turned Bolts . Use bolts conforming to ASTM A307, Grade A with single self -locking nuts or double nuts. Use beveled washers where bearing faces have a slope more than 1:20 with respect to a plane normal to the bolt axis. For turned bolts, provide hex headed bolts of the nominal size specified with a body surface ANSI roughness less than 125 microinches. Ream holes to provide for a light driving fit. Keep bolt threads outside of the holes. Provide a washer under the hexagonal nut.
555.16Connections Using High- Strength Bolts.
(a)Bolted parts. Use only steel material within the grip of the bolt with no compressible material (such as gaskets or insulation). Fabricate steel parts to fit solidly together after bolts are stressed. Remove burrs that prevent solid seating. Limit the slope between the bolted surface and the plane normal to the bolt axis to 1:20.
(b)Surface conditions. Clean dirt, foreign material, and scale (except tight mill scale) from joint surfaces at the ti me of assembly. Remove coating, including inadvertent overspray, from areas within the bolt pattern. In non -coated joints, exclude or remove coating closer than 1 inch or one bolt diameter, whichever is larger, from the edge of holes.
(c)Rotational- capacity t ests. If ordered, or if bolt assembly components were relubricated, perform field rotation -capacity tests according to ASTM F3125 Annex A2 for ASTM F3125 bolts, and ASTM F3148 Annex A1 for ASTM F3148 bolts. Rotational -capacity testing are not required for twist -off bolts (ASTM F3125 Grade F1852 or F2280). (d) Pre-installation verification (PIV) testing. Provide a calibrated bolt tension measuring device with bushings and hardened spacers to test the diameter and lengths of bolt assemblies used in the project. Provide documentation of annual testing by an approved testing agency confirming the accuracy of the bolt tension measuring device. At the start of work, perform a PIV test in a bolt tension measurement device using a representative sample of at least 3 fastener assemblies of each rotation -capacity lot and assembly orientation to be used in the work. Demonstrate the method used to develop a snug condition. Validate the installation method after snugging develops a tension equal to or greater than shown in Table 555-3. Perform periodic retesting when ordered. Table 555-3 Minimum PIV Fastener Tension(1) Nominal Bolt Diameter, inch Specified Minimum
Tensile Strength of
120(2) ksi, pounds Specified Minimum
Tensile Strength of
144(3) or 150(4) ksi, pounds ½ 13,000 16,000 ⅝ 20,000 25,000 ¾ 29,000 37,000 ⅞ 41,000 51,000 1 54,000 67,000 1⅛ 67,000 84,000 1¼ 85,000 107,000 1⅜ 102,000 127,000 1½ 124,000 155,000
(1)Equal to 1.05 times minimum installation tension.
(2)Includes ASTM F3125 Grade A325 and F1852 bolts.
(3)Includes ASTM F3148 Grade 144 bolt.
(4)Includes ASTM F3125 Grades A490 and F2280 bolts. Start all verification tests from the same condition. Install the bolting assembly in a calibrated bolt tension measuring device so that at least three and no more than five threads are located between the bearing face of the nut and the bolt head. Install the bolting assembly to the snug tight condition using the tools, bolting components, assembly configuration, and installation methods to be used in the work. Perform verification tests for bolts too short to be installed in a bolt tension measuring device in solid steel plates with direct tension indicators (DTIs ) instead of a tension measuring device. Fir st calibrate the DTI lot with a longer grip surrogate bolt in the bolt tension measuring device. Pretension the assembly to the required verification tension shown in Table 555-3 and measure an average gap to the nearest 0.001 inc h. Install the short bolt assembly in the solid steel plate with the DTI from the calibrated lot and perform the prescribed pre -tensioning method. Verify that the average gap in the calibrated DTI is no more than the calibrated gap determined from the surr ogate bolt calibration. Do not use DTIs as a bolt tension measurement device for the turn -of-nut and combined installation methods.
(1)Turn of nut verification. After snugging the bolt assembly in the bolt tension measurement device, apply the rotation shown in Table 555-4 to the bolt assembly. After rotation, confirm the bolt tension exceeds that shown in Table 555-3. If tension is less than shown in Table 555-3, determine the cause and resolve before installing bolt assemblies. Cleaning, lubrication, and retesting of these bolting assemblies is allowed if all assemblies are treated in the same manner. To verify bolts that are too short to fit in a bolt tension measuring device, install the bolt in a solid steel plate, snug tighten, and apply the prescribed number of turns from Table 555-4. Fracture of the fastener or stripped threads results in failure of the test. After the assembly is removed, run the nut down the bolt by hand. If the nut can be run down the complete thread length of the bolt, excluding thread run -out, the threads are not stripped and the bolt assembly passes the PIV test. Table 555-4(1) Nut Rotation from the Snug -Tight Condition(2)
Bolt Length
Measured from
Underside of Head
to End of Bolt Geometry of Outer Faces of Bolted Parts
Both Faces
Normal to
Bolt Axis One Face Normal to
Bolt Axis &
Other Face Sloped
No More than 1:20 (Bevel Washer Not Used) Both Faces Sloped
No More Than
1:20 from Normal to Bolt Axis (Bevel Washers Not Used)
Up to & including
4 diameters 1⁄3 turn 1⁄2 turn 2⁄3 turn Over 4 diameters, but no more than 8 diameters 1⁄2 turn 2⁄3 turn 5⁄6 turn Over 8 diameters, but no more than 12 diameters 2⁄3 turn 5⁄6 turn 1 turn
(1)Applicable only to connections where all material within the grip of the bolt is steel.
(2)Nut rotation is relative to bolt, regardless of the element (nut or bolt) being turned. The tolerance is minus 0, plus 60°.
(2)Calibrated wrench verification. After snug tightening the bolt assembly in the bolt tension measurement device, determine the torque required for the installation tool to develop a pretension in the bolting assembly to at least the required verification te nsion shown in Table 555-3. Use the largest torque measured from the three assemblies tested as the minimum installation torque. Use the nut as the turned element in the calibrated wrench method. When tightening from a snug- tight condition, verify that the wrench adjustment selected by the calibration does not produce a nut rotation greater than shown in Table 555-4. If the rotation is greater than shown in Table 555-4, determine the cause and resolve before bolt assemblies are installed in the work. Cleaning, lubrication, and retesting of these bolting assemblies is allowed if all assemblies are treated in the same manner.
(3)Twist -off tension control bolt verification . After snug ti ghtening the bolt assembly in the bolt tension measurement device, tighten the assembly with the installation tool until the splined end shears off. After the splined end has sheared off, confirm the bolt tension exceeds the required verification tension s hown in Table 555-3. If tension is less than shown in Table 555-3, determine the cause and resolve before installing bolt assemblies.
(4)DTI verification. Perform PIV testing for each combination of bolt, nu t, and washer rotational - capacity lot; DTI lot; DTI position and orientation; turned element (bolt head or nut) planned in the work, and when the condition of the fasteners or the knowledge or practice of the wrench operator is in question. Position the DT I under the stationary element or place a hardened washer between the DTI and the turned element. Follow the DTI manufacturer’s recommendations for placement and type of hardened washers. If the bolt is the turned element, place the DTI on the nut side of the fastener assembly. Depending on the DTI position and orientation, a flat plate bushing may be needed for bolt tension measurement device. Install the bolt, nut, washer, and DTI assembly in the bolt tension measurement device so that at least three and preferably no more than five threads are located between the bearing face of the nut and the bolt head. Tension the bolt to the load shown in Table 555-3. If an impact wrench is used, ensure the tension developed using the impact wrench is no more than two- thirds of the required tension. Use a non- impacting method to achieve the required tension. Ensure the number of refusals of the 0.005- inch tapered feeler gauge is no more than shown in Table 555-5. Tabl e 555-5 DTI 0.005- Inch Feeler Gauge Verification Refusal Requirements
DTI Spaces Maximum Verification Refusals
Coated DTIs under
turned element All other cases 4 3 2 5 4 2 6 5 3 7 6 3 8 7 4 9 8 4 Further tension the bolt until the feeler gauge is refused at all spaces without dead flatting the DTI. Do not exceed 95 percent of the average peak tension from the rotation -capacity test results in the bolt in this condition. Remove the bolt from the bolt tension measurement device and run down the nut by hand for the complete thread length of the bolt excluding thread run-out. If any of the above three criteria are not met, determine the cause and resolve before installing bolt, nut, washer, and DTI.
(5)Combined method verification. Apply the manuf acturer’s recommended initial torque and ensure the bolt tension device reads more than the manufacturer’s minimum initial tension. Apply the manufacturer’s recommended angle and ensure the bolt tension measurement device reads a final tension at least the required verification tension shown in Table 555-3. If final tension is less than shown in Table 555-3, determine the cause and resolve before installing bolt assemblies.
(e)Washers. Conform to ASTM F436. U se a hardened beveled washer where the outer face of the bolted parts has a slope greater than 1V:20H with respect to a plane normal to the bolt axis. Use hardened square or rectangular beveled washers for American Standard Beams and Channels. If necessary , clip washers on one side to within seven -eighths times the bolt diameter measured from the washer center. Under the following conditions use hardened washers for connections using ASTM F3125, Grade A325 and Grade A490 bolts:
(1)Under the turned element if the tensioning is done by the calibrated wrench method;
(2)Under both the head and the nut when Grade A490 bolts are installed in material having a specified yield point less than 40 kips per square inch; and
(3)As shown in Table 555-6 . Table 555-6 Washer Requirements for Oversize or Slotted Holes in Outer Plies
Bolt Specified
Minimum
Tensile
Strength Nominal Bolt
Diameter,
inch Hole Type in Outer Ply Oversized or Short -Slotted Long -Slotted 120 ksi ½ to 1½ ASTM F436(1) Minimum 5/16 in-thick plate washer or continuous bar 144 ksi, 150 ksi ≤ 1 > 1 ASTM F436 extra thick or ASTM F436 with minimum ⅜ in-thick plate washer or continuous bar(1) ASTM F436 with minimum ⅜ in-thick plate washer or continuous bar
(1)Not required under the head of ASTM F3125/F3125 Grades F1852 and F2280, or ASTM F3148 Grade 144 bolting assemblies with round heads that meet the requirements of ASME B18.2.6 Fasteners for Use in Structural Applications and have a bearing circle diamet er satisfying the requirements of the relevant ASTM Standard. Do not use multiple stacked washers to satisfy thickness requirements. Alternate design fasteners that provide a bearing circle on the head or nut of at least the diameter of an ASTM F436 hardened washer may be used without washers.
(f)Installation. Use fasteners of the same rotation -capacity lot number for each connection. Protect fasteners from dirt and moisture. Only remove the fasteners from protected storage that are to be installed and tensioned during a work shift. Return unused fasteners to protected storage at the end of each shift. Do not remove as -delivered lubricant from fasteners. Discard and replace fasteners for slip-critical connections that accumulate rust or dirt before instal ling. Snug- tighten all assemblies using the same means and methods as proven in the PIV test. Start snugging with the most rigid part of the connection and proceeding to the free edges. Repeat the snug-tightening sequence until the entire connection is in a snug- tight condition. Install fasteners with specified washers according to Subsection 555.16(e) in properly aligned holes. Tension according to Subsections 555.16(f)(1) through (5). Tension within 10 days of snugging. If there is longer than 10 days between snugging and tension, remove of representative assemblies from the work and conduct new PIV tests. When it is impractical to turn the nut, tension the fastener by turning the bolt, except for the calibrated wrench method, while preventing the nut from rotating when approved. Provide adequate capacity and sufficient air to tension each bolt in 10 seconds if impact wrenches are used. Do not reuse ASTM F3125 Grade A490 fasteners or any fastener which has been galvanized or coated. If approved, non- galvanized ASTM F3125 Grade A325 bolts may be reused once. Touching up or re - torquing previously tensioned bolts (which may have been loosened by the tensioning of adjacent bolts) will not be considered reuse if the tensioning continues from the initial position and does not require greater rotation than shown in Table 555-4.
(1)Turn of nut installation. After snug tightening, apply the applicable rotation shown in Table 555-4 using the same means and methods proven in the PIV test. Apply the rotation starting with bolts in most rigid part of the connection and proceeding to the free edges. Prevent rotation of the part not turned by the wrench during the tensioning operation.
(2)Calibrated wrench installation. After snug tightening, apply the maximum torque as determined in PIV testing to every nut starting with the most rigid part of the connection and proceeding to the free edges. The bolt cannot be the turned element. Return the wrench to touch up previously tensioned bolts which may have been relaxed as a result of the subsequent tensioning of adjacent bolts until all bolts are tensioned to the prescribed amount. Use the calibrated wrench method only when wrenches are calibrated using the PIV test on a shift basis. Recalibrate wrenches when a significant difference is noted in the surface condition of the bolts, threads, nuts, or washers. If manual torque wrenches are used, torque nuts in the tensioning direction when torque is measured. If tightening from a snug -tight condition, verify that the wrench adjustment selected by the calibration does not produce a nut rotation greater than shown in Table 555-4.
(3)Twist -off tension control bolt installation. After snug tightening, shear off the splined ends using the same installation tool used in the PIV test.
(4)DTI installation. After snug tightening, ensure no DTI has more refusals than shown in Table 555-7. Replace DTIs that fail the requirement. Continue to tighten the assemblies until the number of refusals is equal to or greater than shown in Table 555-7 and the feeler gauge can be partially enter ed in at least one gap. Table 555-7 DTI 0.005- Inch Feeler Gauge Installation Refusal Requirements
DTI Spaces Minimum Verification Refusals
Coated DTIs under
turned element All other cases 4 3 3 5 4 3 6 5 4 7 6 4 8 7 5 9 8 5
(5)Combined method installation. Install bolt assemblies in the connection and torque to the initial installation torque provided by the manufacturer. Progress torquing systematically from the most rigid part of the joint to its free edges. Return the wrench to “touch up” previously snugged bolts. After snug tightening, apply the manufacturer’s specified rotation to every turned element. If the bolt length measured from the underside of the head to the end of the bolt exceeds 12 diameters, determine the required rotation by actual tests in a tension device simulating the actual conditions.
(6)Alternate design bolt installation method. If approved, provide alternate fasteners that meet the material, manufacturing, and chemical composition requirements of ASTM F3125, Grade A325 or A490 and:
(a)Meet the mechanical property requirements of the same specification in full -size tests; and
(b)Have body diameter and bearing areas under the head and nut, or their equivalent, at least those provided by a bolt and nut of the same nominal dimension. Install alternate design bolts in connection holes according to the manufacturer’s recommendations and pull the plies to firm contact throughout the connection. Tighten bolts snug- tight without yielding or fracturing the control or indicator element of th e fastener. Further tension fasteners starting with bolts in most rigid part of the connection and proceeding to the free edges. Proper tensioning of the bolts may require more than a single cycle of systematic partial tensioning. Replace individual fastener assemblies if yielding or fracture occurs before the final tensioning cycle. Verify the tension according to Subsection 555.16(d) .
(7)Inspection. Inspect the tensioned fasteners in the presence of the CO. Replace or re -tension loose or relaxed fasteners. Do not remove fasteners by cutting with a torch.
(a)Non-threaded fasteners. Ping each fastener with a hammer to test for soundness.
(b)Threaded fasteners. Use an inspection torque wrench to verify tensioning unless alternate fasteners or DTI devices are used allowing verification by other methods. Calibrate the inspection torque wrench at least once each inspection day. Individually place three fastener assemblies of the same grade, size, and condition as those under inspection in a device calibrated to measure bolt tension. Use a washer under the part turned in tightening each bolt if washers are used on the structure. Use the same material that abuts the part turned in the tension measuring device as used on the structure if washers ar e not used on the structure. In the calibration device, tighten each bolt to the specified tension. Apply the inspecting wrench to the tightened bolt to determine the torque required to turn the nut or head 5 degrees, approximately 1 inch at a 12- inch radius, in the tightening direction. Use the average of the torque required for all three bolts as the job- inspection torque. Randomly select 10 percent (at least two) of the tensioned bolts on the structure in each connection represented by the test bolts. Apply the job- inspection torque to each selected bolt with the inspecting wrench turned in the tensioning direction. If this torque turns no bolt head or nut, the fastener is properly tensioned. If the torque turns one or more bolt heads or nuts, apply the j ob-inspection torque to all bolts in the connection. Re -torque and re -inspect fasteners whose head or nut turns.
555.17Welding. Comply with AASHTO/AWS D1.5, Bridge Welding Code for welding, welder qualifications, prequalification of weld details, and inspection of welds. For tubular connections, conform to AWS D1.1, Structural Welding Code – Steel, Section 10, Part D . Do not weld or tack brackets, clips, shipping devices, or other non- required material to members unless shown in the drawings.
555.18Erection. Install falsework and forms according to Section 562. Coat structural steel according to Section 563. Use steel erectors certified under the AISC, Quality Certification Program .
(a)Handling and storing material. Place stored material on skids above ground. Keep material clean and properly drained. Place and shore girders and beams upright. Support long members (such as columns and chords) on skids placed close enough together to prevent deflection damage.
(b)Bearings and anchorages. Provide and install bridge bearings according to Section 564.
(c)Erection procedures. Erect according to th e approved drawings. Submit revised drawings and verification of stresses and geometry for modifications to or deviations from the approved erection procedure for approval.
(1)Erection stresses. Allow for erection stresses locked in the structure caused by erection methods or equipment that differ from those previously approved. Provide additional material necessary to keep both temporary and final stresses within the allowable limits used in the design. Provide temporary bracing or stiffening devices to accom modate handling stresses in individual members or segments.
(2)Maintaining alignment and camber. Support structural segments to produce the proper alignment and camber in the completed structure. Install cross frames and diagonal bracing during erection to provide stability and ensure correct geometry. Provide temporary bracing at any stage of erection.
(d)Field assembly. Clean bearing surfaces and permanent contact surfaces. Assemble material as shown in the approved drawings and match-marks. Do not hammer, damage, or distort members. For bolted splices and field connections, fill one -quarter of the holes with bolts and one -quarter of the holes with cylindrical erection pins before placing permanent fasteners. For continuous units, pin and bolt all beam and girde r splices and bring the splices to the correct elevations before permanently fastening. For bolted connections, use fit -up bolts with the same nominal diameter as the permanent fasteners, and use cylindrical erection pins with a diameter ⅟ 32 inch larger th an the bolts. Evenly space the pins around the connection. Place pins in the corner holes of the splice plates. Systematically remove fitting -up bolts and cylindrical erection pins and replace them with tightened high- strength bolts. Start from the most rigid part of connection and proceed to the free edges. Release temporary erection supports at a splice or connection only after bolts are installed and tightened. Show special assembly and support situations on the erection drawings.
(e)Pin connections. Use pi lot and driving nuts when driving pins. Drive pins so that the members fully bear on the pins. Screw pin nuts tight and burr the threads at the face of the nut with a pointed tool.
(f)Misfits. Correct minor misfits using small amounts of reaming, cutting, grinding, and chipping. Remove and replace members misfit due to shop fabrication error or deformation during handling or transporting.
555.19Contact with Other Material. Place an unvulcanized virgin polychloroprene rubber (neoprene) waterproofing sheet bet ween the structural steel and timber surfaces. Provide a continuous ⅛- inch thick sheet conforming to AASHTO M 215, with a low temperature Grade 2 and a hardness of 50±5.
555.20Acceptance. Material for steel structures will be evaluated under Subsections 106.02 and 106.03. Construction of steel structures will be evaluated under Subsections 106.02 and 106.04. Bearing devices will be evaluated under Section 564. Coatings will be evaluated under Section 563. Temporary works will be evaluated under Section 562.
Measurement
555.21Measure the Section 555 pay items listed in the bid schedule according to Subsection 109.02 and the following as applicable: When measuring structural steel by the pound, measure structural steel computed according to AASHTO, LRFD Bridge Construction Specifications . When measuring structural steel by the contract quantity, changes in quantities resulting from alternative details proposed by the Contractor and accepted as a part of the drawings are not subject to adjustment according to Subsection 109.06.
Payment
555.22The accepted quantities will be paid at the contract price per unit of measurement for the Section 555 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05 .