515Prestressed Concrete Bridge Members

515.01 Description. This work consists of preparing shop drawings, furnishing and

manufacturing prestressed concrete bridge members, testing, fabricator performed quality control, documentation, shop coating, and handling, transporting, storing, and erecting prestressed con crete bridge members. Prepare shop drawings and erect prestressed concrete bridge members, according to Item 501 and the additional requirements specified below. Shop coating shall conform to Item 512.

515.02 Fabricator Approval Procedure. Select fabricators that are pre-qualified and evaluated

by the Office of Materials Management (OMM) according to Supplement 1079 and listed by the Department before the Contract letting Date.

515.03 Levels of Fabricator Qualification. There are three levels of fabricator qualification.

OMM will classify each fabricator at the highest level of fabrication it is qualified to perform. Level Description of Capabilities 1 Straight strand prestressed box beam members 2 Straight strand prestressed I-beam members 3 Draped strand prestressed I-beam members

515.04 General. Produce all members according to Item 511, except as otherwise specified

herein.

515.05 Fabricator Documentation Responsibility. The fabricator shall keep and maintain

records for each project bid line number concerning:

515.06 Shop Drawings. Provide shop drawings conforming to 501.04 and the following

requirements. Include all details, dimensions, dimensional tolerances, and size of materials, lifting devices, inserts, reinforcing steel supports, fabricator incorporated reinforcing, contractor supplied items, piece mark diagrams for field connection and erection of a ny steel and all prestress members, and all other information necessary for the complete fabrication and erection of the prestressed members. Show all items that will be incorporated into each prestressed member, including Contractor supplied hardware. All steel hardware to be incorporated into the prestressed member and added after Contract Sale shall be galvanized according to 711.02; and meet clearances specified in 509.04. Provide mill certs to the fabricator, prior to the prefabrication meeting. Provide the detensioning procedure and pattern conforming to 515.16.

515.07 Pre-Fabrication Meeting. At least 3 days after the Department receives shop drawings,

conduct a pre -fabrication meeting at the fabricator’s facilities, or another location agreed to by all parties. As part of the pre -fabrication meeting request, provide a initial fabrication schedule for the prestressed beam project including:

515.08 Materials. Furnish materials conforming to:

Reinforcing steel ................................... 509 Concrete ........................................... 515.15 Portland cement ............ 701.01 thru 701.09 Aggregate * ...................................... 703.02 Air-entraining admixture ................. 705.10 Chemical admixtures for concrete ... 705.12 Prestressing steel .............................. 711.27 Transverse tie rods ........................... 711.01 Welded wire reinforcement.............. 709.12 * For fine aggregate, use natural sand for members without a separate wearing course. Modify coarse aggregate as follows: Do not allow more than 0.4 percent deleterious materials. For gradation, use No. 6, 67, 68, 7, 78, or 8 size coarse aggregate.

515.09 Materials Approval. The fabricator shall control, test, and validate material

requirements for all materials either incorporated into the prestressed fabricated item or supplied under Item 515 as component parts to the fabricated items. The fabricator shall provide Supplement 1079 documentation to the inspector at the time of final inspection. The Department will not sample materials at the fabricator’s shop for Department approval. The Department will randomly sample materials to verify the fabricator’s performance.

515.10 Casting Beds. Use steel or concrete casting beds set above grade to ensure the beds

remain above the accumulation of water resulting from production and curing operations. Design beds and abutments capable of safely resisting all forces applied to them without apprecia ble movement or deflection. These forces include compression and eccentric forces due to end-jacking operations, forces at hold down points when draped strands are used, and downward forces due to the dead weight of the members. Verify casting bed losses a nnually and provide the data as an update to the Fabricator ’s Quality Control Plan.

515.11 Weather Conditions During Production. Make temperature change adjustments to

initial strand tensioning according to PCI Quality Control Manual 116.

515.12 Equipment. Provide hydraulic jacks of sufficient capacity and stroke to tension strands.

Use either single or multiple strand tensioning. Provide tensioning jacks equipped with automatic cutoff valves and equipped with 6 inch (150 mm) minimum diameter gages that provide readings at 500 pound (2 kN) increments. Calibrate gages for the jacks with which they are to be used. Have a graph or table showing the calibration available for the inspector. Calibrate jacks according to a method acceptable to the Laboratory at le ast every 6 months or as required by the Director. Maintain calibration documentation as part of the project’s QC inspection records. Design the jacking system to ensure uniform stress in all strands. If simultaneously tensioning multiple strands, use approved types of dynamometers to equalize the initial stress on all strands before applying the full tensioning load with the master jack Provide dynamometers with sufficient capacity to ensure that the desired readings are in the middle to upper range.

515.13 Inspection Facilities. The fabricator shall provide the inspector office accommodations

conforming to the following requirements:

515.14 Construction Methods. Use metal forms capable of producing members within the

tolerances shown on the plans. Forms made of material other than metal may be used for bulkheads, voids, and shear keys. Ensure that the surfaces of the forms in contact with the concrete are smooth and the joints between panels are tight. The soffit form shall have a plane surface at right angles to the vertical axis of the members and have the two bottom edges beveled 3/4 inch (19 mm) with a triangular strip built into the forms. Increase the length of the forms for elastic shortening and normal concrete shrinkage, and design the forms to accommodate this movement. Provide water-resistant formwork for box beam voids constructed of a material that resists breakage and deformation during placement of concrete. Provide form material that does not excessively increase the dead load of the beams. Prevent the release agent from contacting the prestressing strands or reinforcing steel. Install and assemble reinforcing steel according to the approved shop drawings. If authorized, weld reinforcing cages using welders qualified to AWS D1.4 . Do not weld epoxy coated or galvanized reinforcing steel unless approved by Office of Material Management. Repair all coating areas damaged by welding according to the coating manufacturer’s instructions. Reject reinforcing steel with a loss of cross-section of reinforcing caused by welding. Provide a protective covering for the prestressed steel from the elements until the strand is pulled into the bed. Accurately place strands in the positions shown on the shop drawings. Do not use strands with kinks, bends, nicks, broken wires, scale, loose rust, or other defects. The fabricator may use slightly rusted reinforcing steel provided the rust is not sufficient to cause visible pits. Before placing the concrete, carefully clean the strands of all dirt, grease, oil, or other foreign matters. Do not splice strands. Tension strands uniformly to the stress indicated on the shop drawings. If multiple stands are stressed simultaneously, use dynamometers to equalize the initial stress on all strands before applying full tension load with master jack. Measure the required stress in the strands using the calibrated jacking equipment gages, and check the measured stress by the elongation of the strands. If the stress from the gages and the measured elongation are not within a 5 percent tolerance of the design, stop stressing the strands and determine the reason for the differences. The quality control specialist shall keep a record of the jacking forces and elongations of all strands. Secure the strands by suitable anchorage devices capable of developing at least 85 percent of the ultimate strength of the strands. The anchorage shall not allow the strand to slip after the tensioning operation. If using draped strands, the loss of stress due to friction shall not exceed 5 percent. Tension the strands at both ends. The quality control specialist shall measure the loss due to friction by a procedure approved by the Office of Material Management. Place hold-down points within 3 inches (90 mm) of the locations shown on shop drawings and within 12 inches (0.3 m) of the locations shown on the plans. Unless otherwise shown in the plans, do not install inserts or holes in the beam web within a distance of 1.5 times the beam height from the end of the beam.

515.15 Concrete. The fabricator shall provide concrete mix designs to Office of Materials

Management. The submittal will include:

515.16 Release of Prestressing Strands. Do not release prestressed strands until the concrete

reaches a minimum strength of 4000 pounds per square inch (28.0 MPa), or plan defined release strength. Determine strength of concrete by testing cylinders produced according to AASHTO T 23 and cured in the same method as the member. Test cylinders in the fabricator’s laboratory. Assure all tested cylinders obtain the required strength of 4000 pounds per square inch (28.0 MPa) or the plan defined release strength. Provide the Department the ability to witness the cylinder testing by notifying the inspector before testing. Before releasing prestressed strands, loosen or remove forms and hold -downs and all other attachments restricting either horizontal or vertical movement of prestressed members. Release the strands immediately upon completing accelerated curing. Heat releas e and burn the strands simultaneously between each beam and at all exposed points between anchorages, and follow an approved pre-determined pattern, to equalize the forces being transferred to the various areas of the cross-section of the member. Submit an y alternative strand release plans during the prefabrication meeting to OMM for approval. For heat release, use a low-oxygen flame to uniformly heat at least a 4 inch (100 mm) long section of strand before completely cutting the strand.

515.17 Fabrication Tolerances. Construct all members to conform to the following tolerances.

TABLE 515.16-1, BEAM DIMENSIONAL TOLERANCES Description Box Beam I Beam Length of beam ±1/8" per 10 ft (1 mm/m) max ±3/4" (19 mm) ±1/8" per 10 ft (1 mm/m) max ±1" (25 mm) Depth of beam ±1/4" (6 mm) -1/4" (6 mm) +1/2" (13 mm) Depth of I beam flange including fillets N/A ±1/4" (6 mm) Beam (box)/Flange (I) Flange Width ±1/4" (6 mm) -1/4" (6 mm) +3/8" (10 mm) Flange Thickness excluding fillets

515.18 Prestressed Member Acceptance and repair. Throughout the fabrication process reject

all prestressed members not meeting specification requirements except as noted below for camber. For all rejected members provide the Department with a complete description of the rejection, and unless waived by the Director, an Ohio registered professional engineer’s written evaluation of the criticalness of the rejection and the professional engineer’s proposed repair method that will repair the rejected member to an acceptable condition. The Department will determine the acceptability of the member and the repair procedure. If acceptable, the fabricator will only make repairs witnessed by the Department’s inspector unless waived by the Director. Use the Precast/Prestress Concrete Institute’s Manual for the evaluation and repair of Precast, Prestressed Concrete Bridge Products MNL-137-06 as a general guide. The Department will not accept for shipping, prestressed members with measured camber exceeding the Design Camber (D30), used to establish the seat elevations, according to 511.07, by more than the Sacrificial Haunch thickness nor camber more than one inch less than Design Camber, until a corrective work plan has been approved by the Engineer. The plan shall be signed, sealed and dated by an Ohio Registered Engineer and shall include all revised plan information necessary to place the deck to the plan thickness. If the prestressed members are acceptable, exclusive of the deviation from Design Camber, the Department will pay for all costs incurred resulting from measu red camber exceeding Design Camber or more than 1 inch under Design Camber calculated for the actual beam age at the time of deck placement, as Extra Work, 109.05.

515.19 Handling Storage, Transportation, and Erection. Handle, store, transport, and erect

the members in an upright position. The direction of support reactions during storage and transportation shall be the same as the member will experience in its in -service position. Do not ship prestressed members until the concrete obtains its 28-day design strength and the inspector’s approval. Provide at least 30 inches (762 mm) horizontally between each beam for inspection. Provide at least 8 inches (200 mm) of vertical clearance from the bottom. Use storage support locations as close as practical to the in -service support locations. During sto rage, provide unyielding horizontal supports and bracing capable of maintaining the members in a vertical position. Transportation support locations shall be the sole responsibility of the fabricator with respect to member stresses and safe delivery to the job site. Obtain the Director’s written approval to transport the members in a position other than vertical., Provide lifting devices capable of withstanding the required loads to lift and erect the members. During erection, accurately place the prestressed beams on their bearings to ensure a uniform load on all bearings. When shifting a member, lift the member up completely off of its bearings. Temporarily brace the first I-beam erected to its substructure support units in the vertical position before releasing the beam from the crane. Tie each subsequent I - beam to the previously braced beam(s). Provide bracing after erection adequate to prevent sliding, tipping, or other movement that may result from high winds, creeping down the grade, or other causes, until placement of the diaphragms. Within any one day erect and brace at least 2 adjacent members in any one sp an before suspending operations for the day. Place box beams to ensure a correct fit of the shear keys and ensure proper grouting of the shear keys. To prevent box beams from rotating, place removable blocking wedges between the beams at each tie rod location, where tie rods pass through the joint, prior to torquing. Offset blocking 6 to 12 - inches from the centerline of the tie rod on each side. Insert blocking wedges to a maximum depth of 5-inches in the keyway throat. A minimum 1.5 -inches keyway throat width must be maintained throughout the tie rod torquing process. After placing the beams and installing tie devices, fill the longitudinal shear keys as shown in standard drawing PSBD -1-25 using non-shrink shear key grouts, 705.22, approved by OMM. Stop the grout at the top of the shear key as shown. The grout in the shear key will crack if extended above the shear key into the throat. Mix, install, and cure the grout according to the manufacturer’s published recommendations to obtain a design com pressive strength of 5000 pounds per square inch. Once the grout has reached compressive strength of 5000 pounds per square inch, remove blocking wedges. On full width construction, do not pour the bridge decks or allow vehicular loads on a prestressed concrete box beam structure until the grout in the shear keys obtains the specified design strength of 5000 pounds per square inch. On part width construction, do not allow the deck pour or vehicle loads on each stage until after the shear keys in that stage obtain 5000 pounds per square inch. Stage 1 can have vehicle loads during construction of stage 2. Do not open the stage 2 portion of part width construction or pour the closure pour portion of the deck as shown in PSBD -1-25 until after the grout in the shear key between stages obtains the specified design strength of 5000 pounds per square inch. At the Director’s discretion, repair or replace members damaged by improper handling, storage, transportation, or erection.

515.20 Safety Requirements. Provide effective safety measures to prevent injuries to personnel

due to breakage of strands or failure of anchorage devices during the tensioning operations. Provide adequate protection and assure the OMM inspector can perform inspection of beams and manufacturing processes. The Department inspector will report any inadequate safety precautions to the plant QCS and to OMM if fabricator remedial action is not taken. OMM inspectors will follow safety rules established by the fabricator, at a minimum. Where fabricator safety rules interfere with the inspectors’ duties, the process should be altered to allow the inspections to be performed while maintaining the required level of safety.

515.21 Method of Measurement. The Department will measure Prestressed Concrete Bridge

Members by the number of members. The Department will measure the intermediate diaphragms by the number of each placed.

515.22 Basis of Payment. Payment for prestressed concrete beams include all inserts, sleeves,

fittings, reinforcing steel fully or partially encased in the members, threaded rods, embedded inserts, embedded bearing sole plates, temporary bracing, fixed anchor dowels, and all tran sverse tie rods necessary to complete this work. The Department will consider all costs associated with all structural steel, including bolts, nuts, washers and plate washers for steel intermediate diaphragms, as well as concrete and reinforcing steel for cast-in-place concrete intermediate diaphragms as incidental to the intermediate diaphragms. The Department will pay for expansion joint end diaphragms, semi -integral diaphragms, pier diaphragms, bearing load plates, bearing pads, and other expansion materials, separately. The Department will not pay for repaired or replaced members damaged by improper handling, storing, transporting, or erecting. The Department will pay for accepted quantities at the contract prices as follows: Item Unit Description 515 Each Prestressed Concrete Non- Composite Box Beam Bridge Members, Level 1 515 Each Prestressed Concrete Composite Box Beam Bridge Members, Level 1 515 Each Straight Strand Prestressed Concrete Bridge I-Beam Members, Level 2 515 Each Draped Strand Prestressed Concrete Bridge I-Beam Members, Level 3 515 Each Intermediate Diaphragms ITEM 516 EXPANSION AND CONTRACTION JOINTS, JOINT SEALERS, AND BEARING DEVICES

Prestressed Concrete Bridge Members in other states

• Alabama 513 · PRESTRESSED CONCRETE BRIDGE MEMBERS
• Georgia 507 · Prestressed Concrete Bridge Members
• Oklahoma 503 · Prestressed Concrete Bridge Members