503.01 Prestressed Concrete Bridge Members
314 502.05 METHOD OF MEASUREMEN T — VACANT
502.06 Basis of Payment
The Department will pay for each pay item at the contract unit price per the specified pay unit as follows: Pay Item: Pay Unit:
A.ENGINEERED FALSEWORK Lump Sum
B.FALSEWORK ENGINEERING SERVICES Lump Sum
C.DETOUR BRIDGE Lump Sum Unless specified in the Contract as pay items, include the cost of forms and falsework, Engineered Falsework and Falsework Engineering Services , in the Contract unit price for the relevant concrete pay item. If the Contractor chooses to use stay -in-place f orms, the Department will not pay for additional quantities of concrete and reinforcing steel in excess of the quantities shown on the Plans. Include the cost of temporary retaining structures and temporary water control systems in the Contract unit price for the relevant excavation pay item. The Department will pay for piling and drilled shafts for detour bridges in accordance with Section 514, "Driven Foundation Piles," and Section 516, "Drilled Shaft Foundations."
503.01 Description
This work consists of providing and placing precast, prestressed beams and other precast concrete bridge component s in the bridge structure. Post -tensioned concrete bridge members are not covered by Prestressing. The stressing of bridge members in which the stressing forces are placed in the steel strand before the concrete is placed. Detensioning. The transfer of stress from the steel strand tendons into the hardened concrete. Sweep. Horizontal deviation from a straight line parallel to the centerline of the member. Camber. Upward deflection of the member caused by prestressing forces. PRESTRESSED CONCRETE BRIDGE MEMBERS 503.02 315 503.02 MATERIALS
A.General Provide materials in accordance with the following sections and subsections: Material: Section or Subsection: Structural Concrete 509 Joint Fillers and Sealants 701.08 Reinforcing Steel for Structures 511 Steel Wire Strand for Prestressing 723.03
B.Concrete Provide Class P concrete meeting the minimum strengths required by the Contract unless otherwise required by the Contract. Design concrete to have at least 75 percent of the 28 -day strength required by the Contract at the time of detensioning, unless otherwise required by the Contract. Cast all members with the same strength required by the Contract using the same mix design.
C.Strand and Structural Steel For a structure, provide t he same type, grade, and manufacturer of strand. For each member, limit the variation in modulus of elasticity to ±1 percent for all members in the same span. Tension stress -relieved strand to 70 percent of the ultimate strength. Tension low -relaxation strand to 75 percent of its ultimate strength. If substituting low -relaxation strand for stress -relieved strand, tension it to 70 percent of the ultimate strength. Make strand substitutions for all strands, in all members in the same span. The Department will not allow substituting stress -relieved strand for low-relaxation strand. Provide strands free of material that may reduce the bond with concrete, including, but not limited to the following: Corrosion that causes pitting or loss of section, Scale, Flaking, Dirt, Grease, Wax, or Oil. Do not use strands that have been broken, steamed, or fully stressed and relaxed more than twice. The Department will allow no greater than 5 percent of the strand in a pattern to contain one broken wire if the 5 percent stressing tolerance is not exceeded. Do not weld to strand or weld near strand.
503.03 Prestressed Concrete Bridge Members
316 503.03 EQUIPMENT
A.Prestressing Equipment Prestress using jacking equipment approved by the Engineer. Use hydraulic jacks that provide and sustain the Contract required forc es, equipped with a pressure gauge or a load cell to determine the jacking stress. Provide plumbing and gauges that prevent fluctuation in the gauge readings before the release of the jacking load. Measure initial stress using a dynamometer or other gradu ated device that can be read within a tolerance of ±100 lb [±500 N]. Measure the final stress with a graduated device that can be read within a tolerance of ±2 percent of the stress. The Department will not allow the use of load cells to measure stress l ess than 10 percent of the cell capacity. Post the allowable operating range on or near the measuring device dial or display. Measure strand elongation within a tolerance of ±0.1 in [±2 mm]. Use jacks and stress measuring gauges calibrated by a testing la boratory approved by the Department. Calibrate each jack and gauge as a unit, with the jack cylinder extended to the position corresponding to final jacking force. Provide a certified calibration chart or curve for each jack and gauge combination. Calib rate annually. Make additional calibrations under the following conditions: After major maintenance, Stresses and elongations differ more than specified limits, or Erratic results are encountered.
B.Forms and Beds Provide forms and beds in accordance wit h Section 502, “Forms, Falsework, and Temporary Works,” unless otherwise required by the Contract. Use only steel forms, except the Department will allow single -use wood bulkheads. The Department will not allow the use of alumin um forms or finishing tools. Provide smooth, mortar -tight forms without surface irregularities. Repair form imperfections that cause the following: Reduce the concrete cover by more than ¼ in [6 mm], Protrude more than 1 in [25 mm], or Cover more than 5 percent of the total surface area. Provide a ¾ in [19 mm] bevel on the exposed edges of prestressed concrete members except for the top of the top flange. Support forms on unyielding casting beds. Use abutments, beds, and forms designed by a registered professional engineer in the State of Oklahoma. Design beds to minimize differential settlement and movement.
C.Calibration Records Keep calibration records for equipment. Use calibration records for tensioning. PRESTRESSED CONCRETE BRIDGE MEMBERS 503.04 317 503.04 CONSTRUCTION METHODS
A.Shop Draw ings Submit shop drawings for prestressed concrete bridge members in accordance with Subsection 105.2, “Plans and Working Drawings.” Ensure the shop drawings include the following: Title sheet with the following: Index of shop drawing sheets, and General notes; Erection sheets showing the following: Location of members, anchor bolts, and diaphragms, Beam lengths and spacing, Bearing centerlines, Span numbers, and Construction phases; Detail sheets of each fabricated mem ber and component showing the following: Member dimensions, Pretensioned and mild reinforcement, Plates, Chair and tie requirements, Inserts, Diaphragm holes, Dunnage and handling locations, Piece mark locations, Bills of materials, and Design information. Ensure the design information on the detail sheets includes the following: Casting length adjustment due to elastic shortening, Strand specification, Stressing data, Compressive strength requirements. Include detail sheets for fabricated components such a s bent rebar, embedded plates, anchor plates, and bearing pads as necessary. Show items such as reinforcing steel, strand, anchors, inserts, and diaphragm holes in detail to avoid placement conflicts. Show, in a sketch or note, the lap lengths of reinfor cing steel, including steel mesh, maximum strand support (chair) spacing, and reinforcing added to support other reinforcing.
B.Contractor’s Quality Control Provide certified quality control (QC) personnel (sepa rate from production personnel); a productio n and QC procedures manual, inspection, and testing to ensure prestressed concrete bridge members comply with the Contract.
503.04 Prestres Sed Concrete Bridge Members
318 Submit a production and QC procedures manual to the Engineer for approval before fabricating members. Include step -by-step details of the fabricating methods for member types and controlling quality. Resubmit the manual every two years or when procedures change. In the manual, describe the following: Stressing procedures, Concrete mix design, Batching and mixing, Placement and finish ing, Curing, Materials requirements, and Other production practices. In the stressing procedures, describe the following: Initial strand tensioning to equalize stresses and eliminate slack in the strands, Uplift and hold -down devices, Pretensioning and det ensioning methods, Elongation and stress measurements, and Anchorage details. In the QC procedures, describe the following: Materials sampling and testing procedures, Bed and product inspection methods, Member identification, Record keeping for bed and pro duct inspection, Stressing records, Materials testing, Calibration records, and Any other QC functions. Describe the use of standard testing methods, such as those from ASTM or AASHTO. Submit QC records to the Engineer upon request.
C.Preparation of Beds and Forms Before each use, clean beds and forms of debris and contaminants. Use commercial quality form oil, or another form release agent approved by the Engineer, that allows the release of the forms and does not discolor the concrete. Prevent build -up of release agents. Prevent contamination of bonded reinforcement, prestressed or non -prestressed, by the form release agent. Clean or replace contaminated reinforcement. Make form joints smooth and tight to prevent cement paste leakage. Maintain forms and ensure the forms conform to the dimensions of the structure shown on the Plans. Check form alignment and grade before casting in accordance with the approved production or QC manual. Maintain form alignment during the casting operation. PRESTRESSED CONCRETE BRIDGE MEMBERS 503.04 319 D. Tensionin g Requirements
1.General Notify the Engineer before tensioning to allow inspection. Prestress members using the following pretensioning method: Tension prestressing strands, Place and cure concrete, and Stress the concrete by releasing the strands from anchorage after the member reaches the strength required by the Contract. Complete post -tensioning in accordance with Section 517, “Post -Tensioning.” Tension straight or draped strands using a single or multi -strand stressing met hod. Design the stressing method to ensure uniform stress among and along the strands. Leave space between members to allow for cutting the strands during release. During stressing, record the stressing measurements, date, time, and ambient temperature. Inspect the strands after tensioning. Clean or replace strands contaminated by form release agent. Restress the strands as directed by the Engineer before placing the concrete if more than 84 hr has elapsed since stressing.
2.Initial Tensioning Equally tension each strand to eliminate slack before starting elongation readings. Use a tension intensity from 5 to 25 percent of the final jacking force. Mark each strand after initial tensioning (but before final tensioning) and after final tensioning to me asure elongation and monitor each anchor wedge for slippage.
3.Target Stressing Values Calculate the target force and elongation in accordance with the following: The target force equals the total jacking force needed for tensioning; The target elongatio n corresponds to the target force; Make appropriate allowances for losses, such as friction, slippage, and relaxation of anchors and splices; and Adjust target values if the temperature difference between the strands and the concrete at placement is greate r than 30 °F [15 °C]. Limit overstressing of strands to 80 percent of the ultimate strength shown on the manufacturer’s mill certification.
4.Stress Measurement Measure strand tension using a pressure gauge or load cell. Mark strands, without damaging them, to measure elongations. For single and multi -strand stressing, record the force and elongation measurements for each strand and strand group. Monitor slippage of individual strands
503.04 Prestressed Concrete Bridge Members
320 for multi -strand stressing, and restress individual strands to compl y with the Contract. Record each strand heat number. Tension until the force and elongation are both within ±5 percent of the respective target value. Ensure the control measurements of force and elongation algebraically agree within ±5 percent. Stop te nsioning before reaching the targets if the force or elongation exceeds the respective target value by more than 5 percent. If discrepancies occur, check the entire stressing operation, and determine and correct the source of error before proceeding.
5.Draped Strands Tension draped strands using one of the following methods. Partially jacking the strands in a straight position from one end of the bed and finishing by vertically displacing the strands into their draped positions; or If more than two beams are on the casting bed, jacking from both ends of the bed and holding the strands in the draped position using rollers, pins, or other low -friction devices approved by the Engineer.
6.Strand Splicing Use no more than one splice per strand. Splice stran ds of similar physical properties with the same source and “twist” or “lay.” During multi -strand stressing, splice either less than 10 percent or 100 percent of the strands. Locate splices outside the prestressed members.
7.Debonding Strand Provide deb onding on strands as required by the Contract. Use one of the following methods: Interlocking plastic tubing, Solid plastic tubing, Two layers of split plastic tubing with seams greater than 90° apart, or Another method approved by the Engineer. Seal ends and seams of debonding with water resistant tape. Ensure debonding is within 2 in [50 mm] of the target length. Measure the length of debonding to the end of the plastic seal.
E.Concrete
1.General Perform concrete work in accordance with Section 509, “Structural Concrete,” except as modified in Section 503. Consolidate the concrete internally, or internally and externally. Do not damage or displace reinforcement during consolidation. Replace reject ed members, at no additional cost to the Department. The Engineer will not accept concrete containing cement balls or that segregates under normal consolidation. Place concrete when the concrete temperature is from 50 °F to 95 °F [10 °C to 35 °C]. Use Type I or Type III cement in Class P concrete. PRESTRESSED CONCRETE BRIDGE MEMBERS 503.04 321 Obtain reinforcing steel cover using plastic coated, epoxy coated, or plastic supports or chairs. Bend uncoated tie wire or metal supports within 1 in [25 mm] of any formed surface away from the form to obtain the cover required by the Contract. Unless otherwise required by the Contract, finish the top surface of members with a rough float, followed by a transverse finishing with a stiff brush. Finish formed surfaces with a Class 1 finish in accordance with Subsection 509.04.G(1), “Class 1, Ordinary Surface Finish.”
2.Curing Unless otherwise required by the Contract, cure precast members using the water method, or the steam or radiant heat method in accordance with Section 509, “Structural Concrete.” To prevent surface drying, fog exposed concrete surfaces until regular curing starts. Perform the following if differential movement between forms and beds causes damage to members during curing: Anchor the forms to prevent differential movement, or Loosen side forms when loosening will not damage the members. Record the temperature surrounding the member using at least three continuous temperature recorders per line for steam or radiant heat curin g. Use at least one temperature recorder per line if the expected ambient temperature is less than 40 °F [4 °C] for water curing.
3.Testing Notify the Engineer for inspection before casting. Sample and test in accordance with Section 509, “Structural Concrete,” except as modified by the following: For beams and piles, sample and test each member at least once. Take the sample from a batch of concrete of which more than 50 percent will be incorporated into the member it represents. Sample concrete at a rate of at least one sample for each 10 yd³ [10 m³] of concrete for prestressed stay -in-place form deck panels. Randomly select batches for sampling in advance. Vary sampling patterns for each casting operation. Determin e slump, air content, temperature, and compressive strength from each acceptance sample. Perform additional sampling and testing for quality control. Cure all cylinders in the same manner as the members they represent in accordance with Section 9.4 of AAS HTO T 23 before detensioning. After detensioning, cure the remaining cylinders in accordance with Section 9.3 of AASHTO T 23. From each sample, make and test at least one cylinder for detensioning and three cylinders for 28 -day testing. Make additional cylinders for detensioning and early testing of 28 -day requirements. Test the 28 -day cylinders at 28 days, regardless of any previous testing. Determine sample strength using a cylinder from each concrete member or sample for deck panels for detensioning. Detension when all sample locations in the line attain the detensioning strength required by the Contract.
503.04 Prestressed Concrete Bridge Members
322 Use the average of three cylinders from the same concrete sample to determine sample strength for 28 -day strength. The Department will evaluate failed compressive strength tests in accordance with Department policy on acceptance of low strength concrete cylinder tests.
F.Detensioning Design detensioning procedures to: Minimize shock to the members, Minimize movement against restrained items such as forms, inserts, and holddowns, Prevent members from impacting each other, and Prevent overstressing or damaging members. List the detensioning procedure for each member or reference them on the Shop Drawings. List referenced procedures in the productio n and QC manual. Detension after the concrete attains the compressive strength for release required by the Contract. Detension immediately after steam or radiant heat curing while the concrete is still warm and moist. Prevent the temperature surrounding the members from falling below 45 °F [7 °C] before detensioning. Detension within 6 hr of ending water curing. Limit the tension force to 5 percent over the target stressing force, or 80 percent of the ultimate strand strength, whichever is less if transf erring the stressing force by jacking. Cut or release strands in an order that minimizes lateral eccentricity of prestress. If cutting strand with an acetylene torch, minimize shock loading by heating the strand to induce slow yielding and to relieve str ess, and then cutting. Correct the strand cutting procedure if indications of shock loading, such as brooming of strand, appear. Cut strands flush with the end of the member using a saw or other device approved by the Engineer. The Department will not al low the use of an acetylene torch within 6 in [152 mm] of concrete surfaces. Use wire brushing or abrasive blast cleaning to remove dirt and residue. Clean and paint flush -cut strand ends and adjoining concrete within 1 in [25 mm] of the strand. Coat th e cut strand ends with at least 5 mil [130 µm] of zinc -rich paint containing at least 90 percent zinc. Thoroughly mix the paint before application. Work the paint into voids with a brush or by spraying. Within 14 days of detensioning, use an epoxy modif ied grout to cover the exposed strand ends and zinc-rich paint. Provide epoxy in accordance with Subsection 701.13, “Epoxy Resin and Other Adhesives for General Use With Concrete,” Type E. Ensure the beam ends are ver tical to the beam end sole plates within a tolerance of ±⅛ in/ft [±3 mm/0.3 m] of the beam height. The Department will not allow drilling or coring members without the approval of the Engineer.
G.Storage, Inspection, and Transportation Maintain members i n an upright position. Handle members using the lifting eyes or loops. Support beams in storage and transit within 2 ft [0.5 m] of the designed bearing locations. Support stay-in-place panels and piles as shown on the Shop Drawings. Prevent damage to me mbers during storage, handling, and transportation. Replace damaged members at no additional cost to the Department. Repair minor chipping, spalling, and scars as directed by the Engineer. PRESTRESSED CONCRETE BRIDGE MEMBERS 503.04 323 Mark members with a piece mark as shown on the Shop Drawings. In clude the member mark number, piece number, job identification, and date cast. The Engineer must inspect, approve, and stamp members at least 48 hr before shipment to the Project. Ship only approved and stamped members. The Contractor is responsible for any defects found after shipment. Allow members that attain the required 28 -day compressive strength to age at least 168 hr before shipment.
H.Tolerances Correct the production process if member dimensions approach a tolerance limit specified in Table 503:1, Table 503:2, Table 503:3, and Table 503:4. Immediately notify the Engineer of members that do not meet these tolerances. Check dimensional tolerances before casting and after removal from the forms. Recheck time -dependent tolerances such as length, c amber, and sweep, within 3 days before shipment. Check camber and sweep when the thermal effects of sunlight are negligible, on cloudy days or during the early morning. Check local smoothness with a 5 ft [1.5 m] straightedge. Ensure dimensional tolerance s are in accordance with Table 503:1 for AASHTO girders and bulb -tees , Table 503:2 for prestressed piling, and Table 503:3 for prestressed deck panels: Table 503:1 Maximum Dimensional Tolerances for AASHTO Girders, J Beams, and Bulb Tees Dimensions Tolerance Length ±1 in [±25 mm] Width (overall) +⅜ in, −¼ in [+10 mm, −6 mm] Width (web) +⅜ in, −¼ in [+10 mm, −6 mm] Depth (overall) +½ in, −¼ in [+13 mm, −6 mm] Depth (flanges) ±¼ in [±6 mm] Sweep ⅛ in/10 ft [1 mm/m] Debonding length ±2 in [±50 mm] Variation from end squareness or skew ±3/16 in/ft [±16 mm/m], ≤±1 in [≤±25 mm] Camber variation from design camber Camber variation from design camber ±⅛ in/10 ft [±1 mm/m] For spans of 80 ft [25 m] or less ≤±½ in [≤±13 mm] For spans over 80 ft [25 m] ≤±1 in [≤±25 mm]
503.04 Prestressed Concrete Bridge Members
324 Table 503:1 Maximum Dimensional Tolerances for AASHTO Girders, J Beams, and Bulb Tees Dimensions Tolerance Differential camber between adjacent members ⅛ in/10 ft [1 mm/m] Position of strands Individual ±¼ in [±6 mm] Bundled ±½ in [±13 mm Draped strand holddown point ±20 in [±0.5 m] Position of plates Sole plates ±⅝ in [±16 mm] Other plates ±1 in [±25 mm] Tipping and flushness of plates Sole plates ±0.5%, ≤±⅛ in [≤±3 mm] Other plates ±¼ in [±6 mm] Position of inserts Diaphragm holes ±1 in [±25 mm] Diaphragm hole variation from squareness or skew ±1 in [±25 mm] Other inserts ±½ in [±13 mm] Position of handling devices Parallel to length ±6 in [±150 mm] Transverse to length ±1 in [±25 mm] Position of stirrups Longitudinal spacing ±2 in [±50 mm] Projection above top ±¾ in [±19 mm] Local smoothness of any formed surface ±¼ in/10 ft [±6 mm/3 m] PRESTRESSED CONCRETE BRIDGE MEMBERS 503.04 325 TABLE 503.2 Maximum Dimensional Tolerance for Prestressed Concrete Piling Dimension Tolerance Length ±1 in [±25 mm] Width or diameter ± ⅜ in [±10 mm] Variation from longitudinal axis (bow) ±⅛ in/10 ft [1 mm/m] Variation from end squareness or skew ± ¼ in/ft [±6 mm/0.3 m], ≤±½ in [≤±13 mm] Position of Individual Strands ± ¼ in [±6 mm] Position of handling devices ±6 in [±150 mm] Longitudinal spacing of spiral reinforcement ± ¾ in [±19 mm] Local smoothness of any formed surface ± ¼ in/10 ft [±6 mm/1.5 m] Table 503:3 Maximum Dimensional Tolerances for Prestressed Concrete Stay -in-Place Forms (Deck Panels) Dimension Tolerance Length (in direction of panel strands) +¾ in, −¼ in [+18 mm, −6 mm] Width +¼ in, −½ in [+6 mm, −12 mm] Thickness +¼ in, −⅛ in [+6 mm, −3 mm] Variation from end squareness or skew ±¼ in [±6 mm] Camber, sweep, and warping ±¼ in/10 ft [±6 mm/3 m] Position of individual strands Vertically +0 in, −¼ in [+0 mm, −6 mm] Horizontally ±½ in [±12 mm] Position of handling devices Parallel to length ±3 in [±75 mm] Transverse to length ±2 in [±50 mm] Local smoothness of any formed surface ±¼ in/10 ft [±6 mm/3 m]
503.06 Prestressed Concrete Bridge Members
326 I. Corrective Actions Correct members that do not meet the tolerances specified in Table 503:1, Table 503:2 , or Table 503:3 , in one of the following ways, at no additional cost to the Department: Replace the member. Correct the member tolerance problem as directed by the Engineer. If unable to correct a usable member, submit the member f or review and acceptance at a reduced price in accordance with Subsection 105.3, “Conformity With Plans and Specifications.” Include a description of the problem and the proposed corrective action. Provide structural and physical evaluation by an Oklahoma registered professional engineer, as required by the Contract. If the submittal is rejected, replace the member at no additional cost to the Department.
503.05 Method of Measuremen T — Vacant
503.06 Basis of Payment
The Department will pay for each pay item at the contract unit price per the specified pay unit as follows: Pay Item: Pay Unit:
A.PRESTRESSED CONCRETE BEAMS Linear Foot [Meter]
C.PRESTRESSED CONCRETE DECK PANELS Square Foot [Square Meter] If the Contractor chooses to use stay -in-place forms, the Department will not pay for additional quantities of concrete and reinforcing steel in excess of the quantities shown on the Plans. The Department will pay for prestressed concrete piling in accordance wit h Section 514, “Driven Foundation Piles.” The Department will consider the cost of embedded plates to be included in the contract unit price for the relevant prestressed member pay item. BRIDGE DECKS, APPROACHES, RAILS, AND PARAPETS 504.03 327 SECTION 504 BRIDGE DECKS, APPROACHES, RAI LS, AND PARAPETS
504.01 Description
This work consists of constructing concrete bridge decks, approach slabs, and railings and parapets for bridges and other structures.
504.02 Materials
Provide materials in accordance with the following sections and subsections: Material: Section or Subsection: Structural Concrete (Class AA) 509 Reinforcing Steel for Structures 511 Water 701.04 Curing Agents 701.07 Metal Bridge Railing Materials 732.03 Aluminum Alloy Tubes for Railings 732.03 Cast Aluminum Alloy Bridge Railing Posts 732.03 Pipe Railing 732.04 Provide a corrosion -inhibiting admixture for cast -in-place bridge deck concrete and precast deck -form concrete, if using stay -in-place prestressed concrete deck forms.
504.03 Equipment
A.Finishing Machine Provide an Engineer approved, self -propelled finishing machine supported on rails or steel -clad headers capable of transversely finishing the bridge deck and approach slabs. Fasten the rails and headers parallel to the deck centerline and set the line and grade with allowance for dead -load deflections. Before placing concrete, submit a machin e description that includes the make, model, a finishing plan, and an equipment breakdown plan that lists spare equipment and parts and estimates for down time. Spare equipment will include one engine for the finishing machine. Provide enough equipment a nd labor to limit down time so that concrete placement can be completed within the time requirements in Table 509:1 .
B.Fogging Equipment Provide a fogging system that creates fog with pressurized water and a series of foggin g nozzles (not more than 3 ft [1 m] apart) that will continuously cover the finished concrete with cool, moist air. Provide high pressure equipment capable of generating at least 1,200 psi [8.3 MPa] at a flow rate of 2.2 gpm [8.3 L/min], or low -pressure e quipment with nozzles capable of supplying a maximum flow rate of 1.6 gpm [6.1 L/min]. Mount fogging equipment to the trailing edge of strikeoff, work bridges, or both with nozzles positioned to spray above a horizontal plane. Provide hand held foggers f or areas
Source: Oklahoma Standard Specifications for Highway Construction, 2019 Edition. Pages 328–340 of 935.