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indicates in the judgment of the Engineer that the shear connectors being obtained are not satisfactory, the Contractor will be required at his expense to make such changes in welding procedure, welding equipment and type of shear connector as necessary to secure satisfactory results.

At the option of the Engineer, the Contractor may be required at any time to submit sample studs of the type and size used under the contract for requalification in accordance with the procedures of (4) below. Payment for such studs will be made in accordance with subsection 109.04.

(4) Shear connector stud weldability qualification procedure:

a. Purpose. The purpose of this procedure is to prescribe weldability tests which will qualify a shear connector stud for welding under shop or field conditions. The tests may be performed by a university, independent laboratory or other testing agency acceptable to the Engineer. The agency performing the tests shall submit to the manufacturer of the stud a certified report giving procedures and results for all tests including the information listed under h. below. b. Duration of qualification.-A type and size of stud with arc shield, once qualified, is considered qualified until the manufacturer makes any change in the base of the stud, the flux, or the arc shield which effect the welding characteristics.

c. Preparation of specimens.—Test specimens shall be prepared by welding representative studs to the center of square specimen plates, 2 to 4 inch thick, of structural steel, AASHO M 183. At the option of the manufacturer, studs may be welded to a large plate and the specimen plates cut to a size suitable for test equipment used.

Studs shall be welded with power source, welding gun and control equipment as recommended by the manufacturer. Welding voltage, current and time, in accordance with d. below, shall be measured by suitable instrumentation and recorded for each specimen. Lift and plunge shall be at the optimum setting as recommended by the manufacturer.

d. Number of test specimens.-Thirty test specimens shall be welded consecutively with optimum current and time. Optimum current and time shall be the mid-point of the range normally recommended by the manufacturer for production welding.

Thirty test specimens shall be welded consecutively with time held constant at optimum but with current 10% below optimum.

Thirty test specimens shall be welded consecutively with time held constant at optimum but with current 10% above optimum.

e. Qualification tests.-Tensile Tests-Ten of the specimens welded in accordance with d. above, first paragraph, ten in accordance with d., second paragraph, and ten in accordance with d., third paragraph shall be subjected to a tensile test in a tensile strength testing device arranged to exert pulling force on both the stud head and the base plate. A stud will be considered as qualified if all test specimens have a tensile strength above the minimum specified in subsection 717.12.

Bend tests-Twenty of the specimens welded in accordance with d., first paragraph, twenty in accordance with d., second paragraph, and twenty in accordance with d., third paragraph shall be placed in a bend test device arranged to hold the base plate in a fixed position while exerting sufficient force at mid point of the stud shank to bend the shank alternately 30 degrees in opposite directions, from the original position, until failure occurs. A stud will be considered as qualified if, on all test specimens, fracture occurs in the shank of the stud and not in the weld.

f. Retests. If failure occurs in a weld in any of the bend test groups or at less than the specified minimum tensile strength of the stud in any of the tensile test groups, those groups will be retested. If such failure repeats, the stud will fail to qualify.

g. Qualification. For a manufacturer's studs and arcshields to be qualified, each group of thirty studs shall, by test or retest, meet the requirements prescribed in e. above. h. Report of tests. The laboratory report shall include the following:

Drawings which show shapes and dimensions with tolerances of studs, arc shields, and flux.

A complete description of materials used in the studs and arc shields, including the quantity and analysis of the flux.

A certification that the studs and arc shields described in the report are qualified in accordance with g. above. 611.13 Erection. General. The Contractor shall provide the falsework and all tools, machinery, and appliances, including driftpins and fitting-up bolts, necessary for the expeditious handling of the work, and shall erect the metalwork, remove the temporary construction, and do all work necessary to complete the structure as required by the contract and in accordance with the plans and these specifications.

If shown on the plans or in the special provisions the Contractor shall dismantle the old structure on the bridge site in accordance with subsection 202.03.

611.14 Handling and Storing Materials. Material to be

stored shall be placed on skids above the ground. It shall be kept clean and properly drained. Girders and beams shall be placed upright and shored. Long members, such as columns and chords, shall be supported on skids placed near enough together to prevent injury from deflection. If the contract is for erection only, the Contractor shall check the material turned over to him against the shipping lists and report promptly in writing any shortage or injury discovered. He shall be responsible for the loss of any material while in his care, or for any damage caused to it after being received by him.

611.15 Falsework. The falsework shall be properly designed and substantially constructed and maintained for the loads which will come upon it. The Contractor, if required, shall prepare and submit to the Engineer construction drawings for falsework, and working drawings for changes in any existing structure necessary for maintaining traffic, in accordance with subsection 105.02.

611.16 Method and Equipment. Before starting the work of erection, the Contractor shall inform the Engineer fully as to the method of erection he proposes to follow, and the amount and character of equipment he proposes to use, which shall be subject to the approval of the Engineer. The approval of the Engineer shall not be considered as relieving the Contractor of the responsibility for the safety of his method or equipment or from carrying out the work in full accordance with the plans and specifications. No work shall be done until such approval by the Engineer has been obtained.

611.17 Straightening Bent Materials. The straightening of plates and angles or other shapes shall be done by methods not likely to produce fracture or other injury. The metal shall not be heated unless permitted by the Engineer, in which case the heating shall not be to a higher temperature than that producing a "dark cherry red" color. After heating, the metal shall be cooled as slowly as possible.

Following the straightening of a bend or buckle, the surface of the metal shall be carefully inspected for evidence of fracture. Fractured material will be rejected.

611.18 Assembling Steel. The parts shall be accurately assembled as shown on the working drawings and any matchmarks shall be followed. The material shall be carefully handled so that no parts will be bent, broken, or otherwise damaged. Hammering which will injure or distort the members shall not be done. Bearing surfaces and surfaces to be in permanent contact shall be cleaned before the members are assembled. Unless erected by the cantiliver method, truss spans shall be erected on blocking so placed as to give the

trusses proper camber. The blocking shall be left in place until the tension chord splices are fully connected with permanent fasteners and all other truss connections pinned and erection bolted. Splices of butt joints of compression members and railing shall not be "permanently fastened" until the span has been swung. Splices and field connections shall have one-half of the holes filled with erection' bolts and cylindrical erection pins (half bolts and half pins) before placing permanent fasteners. Splices and connections carrying traffic during erection shall have threefourths of the holes so filled.

Fitting-up bolts shall be of the same nominal diameter as the permanent fasteners and cylindrical erection pins will be 1/32-inch larger.

611.19 Riveting. Pneumatic hammers shall be used for field riveting except when the use of hand tools permitted by the Engineer. Rivets larger than 5% inch in diameter shall not be driven by hand. Cup-faced dollies, fitting the head closely to insure good bearing, shall be used. Connections shall be accurately and securely fitted up before the rivets are driven.

Drifting shall be only such as to draw the parts into position and not sufficient to enlarge the holes or distort the metal. Unfair holes shall be reamed or drilled. Rivets shall be heated uniformly to a "light cherry red" color and shall be driven while hot. They shall not be overheated or burned. Rivet heads shall be full and symmetrical, concentric with the shank, and shall have full bearing all around. They shall not be smaller than the heads of the shop rivets. Rivets shall be tight and shall grip the connected parts securely together. Caulking or recupping will not be permitted. In removing rivets, the surrounding metal shall not be injured; if necessary, they shall be drilled out.

611.20 Pin Connections. Pilot and driving nuts shall be used in driving pins. They shall be furnished by the Contractor without charge. Pins shall be so driven that the members will take full bearing on them. Pin nuts shall be screwed up tight and the threads burred at the face of the nut with a pointed tool.

611.21 Setting Shoes and Bearings. Shoes and bearing plates shall not be placed on bridge seat bearing areas that are improperly finished, deformed, or irregular. They shall be set level in exact position and shall have full and even bearing. The shoes and bearing plates may be set by either of the following methods:

Method 1.-The bridge seat bearing area shall be heavily coated with red lead paint and then covered with three layers of 12- to 14-ounce duck, each layer being coated thoroughly

on its top surface with red lead paint. The shoes and bearing plates shall be placed in position while the paint is plastic.

As alternatives to canvas and red lead, and when so noted on the plans or upon written permission by the Engineer, the following may be used:

A. Sheet lead of the designated thickness.

B. A preformed fabric pad composed of multiple layers of 8-ounce duck impregnated and bound with high quality natural rubber or of equivalent and equally suitable materials compressed into resilient pads of uniform thickness. The number of plies shall be such as to produce the specified thickness, after compression and vulcanizing. The finished pads shall withstand compression loads perpendicular to the plane of the laminations of not less than 10,000 pounds per square inch without detrimental reduction in thickness or extension.

C. Elastomeric bearing pads.

Method 2.-The shoes and bearing plates shall be properly supported and fixed with grout. No load shall be placed on them until the grout has set for at least 96 hours, adequate provision being made to keep the grout well moistened during this period. The grout shall consist of one part portland cement to one part of fine-grained sand.

The location of the anchor bolts in relation to the slotted holes in the expansion shoes shall correspond with the temperature at the time of erection. The nuts on anchor bolts at the expansion ends of spans shall be adjusted to permit the free movement of the span.

611.22 Preparing Metal Surfaces for Painting. Surfaces of metal to be painted, including galvanized surfaces, shall be thoroughly cleaned to the condition specified in the special provisions by removing rust, loose mill scale, welding slag, dirt, oil, grease, and other foreign substances. Unless provided otherwise on the plans or in the special provisions, the Contractor may use any of the following methods:

Method A, solvent cleaning.-It is intended that solvent cleaning shall be used prior to the application of paint, and with other methods of surface cleaning.

Soil, cement spatter, drawing compounds, salts, soluble welding flux residues, or other foreign matter (other than grease or oil) shall be removed by cleaning with solutions of alkaline cleaners, provided such brushing with stiff fiber or wire brushes, or by scraping, or by cleaners are followed by a fresh water rinse, or by a combination of these methods.

Oil or grease shall be removed by any of the following methods:

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