13 1 Standards In the event of a conflict among the standards set forth in Book 3 relating to structures, the order of precedence shall be as set forth below, unless otherwise specified: 13 1 Bridges




Название13 1 Standards In the event of a conflict among the standards set forth in Book 3 relating to structures, the order of precedence shall be as set forth below, unless otherwise specified: 13 1 Bridges
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MnDOT Design-Build Program Book 2 – Maryland Avenue Bridge Design-Build Project

Federal Project No. HFL 0354(274) S.P. 6280-353

13STRUCTURES

13.1 General


The Contractor shall conduct all Work necessary to meet the requirements of permanent and temporary structures, including bridges, retaining walls, barriers, buried structures, sign structures, lighting structures, and structure renovations.

13.2 Administrative Requirements

13.2.1 Standards


In the event of a conflict among the standards set forth in Book 3 relating to structures, the order of precedence shall be as set forth below, unless otherwise specified:

13.2.1.1 Bridges


MnDOT Special Provisions*

MnDOT Technical Memoranda*

MnDOT Standard Specifications for Construction*

MnDOT LRFD Bridge Design Manual*

MnDOT Bridge Details Manual, Parts I and II*

MnDOT Bridge Construction Manual*

AASHTO LRFD Bridge Design Specifications

AASHTO LRFD Bridge Construction Specifications

AASHTO Manual for Bridge Evaluation

AASHTO Manual for Condition Evaluation of Bridges

AASHTO Guide Design Specifications for Bridge Temporary Works

AASHTO Construction Handbook for Bridge Temporary Works

AASHTO/NSBA Steel Bridge Fabrication Guide Specification

AASHTO/NSBA Guide Specification for Application of Coating Systems with Zinc-Rich Primers to Steel Bridges

FHWA Post-Tensioning Tendon Installation and Grouting Manual

Post Tensioning Institute (PTI) Guide Specification - Acceptance Standards for Post Tensioning Systems

CEB-FIP Model Code for Concrete Structures (For Time Dependent Behavior of Concrete)

Remaining standards set forth in Book 3

*Document modified for design-build.

13.2.1.2 Retaining Walls


MnDOT Special Provisions*

MnDOT Technical Memoranda*

MnDOT Standard Specifications for Construction*

MnDOT LRFD Bridge Design Manual*

MnDOT Bridge Standard Plans Manual*

MnDOT Bridge Details Manual Parts I & II*

MnDOT Bridge Construction Manual*

MnDOT Standard Plans Manual*

AASHTO LRFD Bridge Design Specifications

AASHTO LRFD Bridge Construction Specifications

AASHTO Guide Design Specifications for Bridge Temporary Works

AASHTO Construction Handbook for Bridge Temporary Works

FHWA Drilled Shafts: Construction Procedures and Design Methods

FHWA Handbook on Design and Construction of Drilled Shafts Under Lateral Load

FHWA Geotechnical Engineering Circular Number 4 Ground Anchors and Anchored Systems

FHWA Manual for Design and Construction Monitoring of Soil Nail Walls

AASHTO Standard Specifications for Highway Bridges

Remaining standards set forth in Book 3

*Document modified for design-build.

13.2.1.3 Buried Structures


MnDOT Special Provisions*

MnDOT Technical Memoranda*

MnDOT Standard Specifications for Construction*

MnDOT LRFD Bridge Design Manual*

MnDOT Design-Build Modifications to the Road Design Manual

MnDOT Bridge Standard Plans Manual *

MnDOT Bridge Construction Manual*

AASHTO LRFD Bridge Design Specifications

AASHTO LRFD Bridge Construction Specifications

Remaining standards set forth in Book 3

*Document modified for design-build.

13.2.1.4 Sign Structures


MnDOT Special Provisions*

MnDOT Technical Memoranda*

MnDOT Standard Specifications for Construction*

MnDOT Design-Build Modifications to the Road Design Manual

MnDOT LRFD Bridge Design Manual*

MnDOT Sign Support Standard (OH Sign Support)

MnDOT Standard Overhead Sign Supports, Interim Design B Details

AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals

Remaining standards set forth in Book 3

*Document modified for design-build.

13.2.1.5 Lighting Structures


MnDOT Special Provisions*

MnDOT Technical Memoranda*

MnDOT Standard Specifications for Construction*

MnDOT Design-Build Modifications to the Road Design Manual

MnDOT LRFD Bridge Design Manual*

MnDOT Standard Plates Manual*

MnDOT Standard Plans Manual*

AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals

Remaining standards set forth in Book 3

*Document modified for design-build.

13.2.2 Personnel


The design of nontypical structural systems shall be performed by a licensed Professional Engineer in the State of Minnesota who has a minimum of four years of cumulative relevant experience in the design of the proposed structural system obtained over the past 12 years. For the purpose of this requirement, nontypical structural systems are defined as follows:

Bridges, excepting those with the following superstructure types:

Prestressed concrete beams

Straight steel girders

Cast-in-place concrete slabs

Retaining walls, with the following exceptions:

Cast-in-place concrete walls

Buried structures, with the following exceptions:

Box culverts

Circular pipes

Sign structures

Lighting structures

13.3 Design Requirements

13.3.1 Bridge Design

13.3.1.1 Geometrics


The front face of abutments for Bridge No. 62626 shall be located a minimum of 60 feet from the centerline of the future northbound and southbound I-35E alignments and the footing shall be designed and constructed to meet all requirements for the future I-35E typical section as shown in Exhibit 11-D (Future Geometry).

Bridge No. 62626 shall be designed and constructed to provide a minimum vertical clearance of 16.33 feet above both the existing and future I-35E profile and geometry.

The Gateway Trail Tunnel (Bridge No. 62X03) shall provide a continuous opening at least 16 feet wide and 11 feet high, except the headwall openings may be smaller to meet requirements of Section 15 (Visual Quality Management). Corner fillets that reduce the opening are allowed at the top of the structure. Corner fillets shall not be larger than 1 foot by 1 foot. The Contractor shall assume a 12-inch structural section for the Gateway Trail when calculating size of the opening.

The Contractor shall not construct bridges with side piers.

All permanent structures shall be constructed at least 10 feet away from MnDOT R/W. Specifically for the Gateway Trail Tunnel, the permanent Gateway Trail Tunnel structure, including portal walls, shall be at least 10 feet from the Trout Brook Tunnel easement.
13.3.1.2 Bridge Type

Superstructure types allowed for Bridge No. 62626 are as follows:

Prestressed concrete beams

Welded steel girders

Reinforced concrete box girders

Post-tensioned concrete box girders

Structure types allowed for Bridge No. 62X03 are as follows:

Concrete box culvert

Three-sided precast concrete bridge

Concrete rigid frame

Bridge No. 62X03 shall satisfy all applicable requirements for buried structures.

The Contractor shall not design bridges with the following:

Intermediate hinges

Fracture-critical components

Floor beams or stringers

All spans in a particular bridge shall have a constant superstructure depth.

The Contractor shall use the same girder material type for all spans in a particular bridge.

Maintain a constant fascia overhang dimension for the entire bridge length.

13.3.1.3 Loads and Load Combinations


The Contractor shall use horizontal acceleration coefficients equal to 3 percent for seismic loads.

Bridges with only three girders require a refined analysis to determine the live load distribution.

The Contractor shall supplement the load combinations in the Standards with the following additional load combination:

MnDOT Strength IV = 1.4(DC, DD, DW, EH, EV, ES, EL, PS, CR, SH) + 1.4(LL, IM, CE, BR, PL, LS) + 1.0(WA) + 1.0(FR) + 0.5/1.2(TU).

13.3.1.4 Structural Analysis and Evaluation

13.3.1.4.1 SPMT Requirements

The Contractor shall use Self Propelled Modular Transporters (SPMT) to move the superstructure of Bridge No. 62626 to its final constructed location. The design of the bridge shall comply with the following requirements:

Analyze bridge spans to satisfy all strength and service limit state requirements when supported by temporary supports, including when bridge spans are in their picked and deflected condition.

Account for the dynamic effects during a bridge move by increasing all dead load stresses by a factor of 1.15 using both cracked and uncracked section properties.

Analyze bridge spans based on elastic behavior with and without the stiffness of the barriers. Model the effect of a cracked and un-cracked section.

A refined analysis is required for the following:

    1. Full superstructure design when the bridge is skewed more than 20 degrees

    2. Full superstructure design when more than one span is moved in a single operation

    3. Design of superstructures for deflection, twist, and concrete cracking

Support all deck formwork from the longitudinal girders. Design and construct the bridge deck to allow for future replacement without shoring.

Design the deck for crack control using a Class 2 exposure condition at its picked and fully deflected condition. Design the medians, sidewalks, and barriers for crack control using a Class 1 exposure condition at its picked and fully deflected condition.

Analyze the span for displacements and twist during a bridge move in accordance with DBSB-2499 (SPMT Bridge Construction).

Use a reduction factor, Фw, equal to 1.0 when determining the compressive stress limits for prestressed concrete beam bridges in accordance with Article 5.9.4.2.1 of the AASHTO LRFD Bridge Design Manual. For post-tensioned concrete box girders, calculate the reduction factor, Фw, in accordance with the AASHTO LRFD Bridge Design Manual.

Provide diaphragms at interior supports for bracing, connections, and local bearing. The SPMT blocking shall be considered an interior support.

Diaphragms shall be detailed to provide the necessary compression flange stability under temporary SPMT cantilevered support conditions.

13.3.1.5 Concrete Design


Prestressed concrete beams may be made continuous for full negative live load at intermediate supports only with internal post-tensioning.

Prestressed concrete beams without post-tensioning shall be designed as simply supported (with no continuity). For bridges containing prestressed concrete beams, the Contractor shall use I-beams or rectangular beams contained in the MnDOT Bridge Details Manual, Part II.

Debonded prestressing strands are not allowed.

The Contractor may use the CEB-FIP Model Code for Concrete Structures (For Time Dependent Behavior of Concrete) in lieu of the AASHTO LRFD Bridge Design Specifications approximate methods.

The Contractor shall not use adhesive anchors for traffic rails. All anchors and attachments shall use embedded connections.

The ultimate capacity of prestressed concrete beam requirements in the MnDOT LRFD Bridge Design Manual Memo to Designers 2005-01 shall not apply.
13.3.1.6 Decks and Deck Systems

The Contractor shall design all decks and slabs using cast-in-place concrete. The minimum concrete thickness of the deck shall be 9 inches.

The Contractor shall assume a minimum of 0.5 inches of wear for determining composite cross-section properties. The self weight of this assumed wear shall be included in design.

The Contractor shall design post-tensioned concrete structures for zero tension at the top of the deck under service loads.

The Contractor shall install a chip seal wearing course on Bridge No. 62626 in accordance with DBSB-2401.35 (Chip Seal Wearing Course). The wearing course shall not be placed until after the bridge is in its final position.

The wearing course shall not be included in structural capacity computations for the design of bridge decks and slabs.

The Contractor shall not use bituminous or bituminous with membrane wearing courses for permanent bridge deck construction.

Stay-in-place forms are not allowed.
13.3.1.7 Foundations

Allowable foundation types for Bridge Nos. 62626 and 62X03 are as follows:

Steel H-piles

Cast-in-place concrete piles

Drilled shafts

The Contractor shall design foundations for a maximum total settlement equal to the lesser of 0.1 percent of the span length supported or 1 inch, and for a maximum differential settlement of 0.5 inches within an individual pier or abutment.

The Contractor shall determine the lateral load resistance of piles for design, using soil parameters obtained from the Foundation Analysis and Design Report. The Contractor shall not use an internal friction angle greater than 35 degrees or soil modulus greater than 125 pounds per cubic inch in the analysis.

The Contractor shall check the overall stability of earth slopes in front of all structures including bridge abutments and piers. Overall stability includes internal, external, compound, and global. The factor of safety for slope stability shall be 1.5 or greater. The steepest slope allowed shall be 1:2 (V:H).
13.3.1.8 Abutments and Piers

The Contractor shall design all abutments and piers using cast-in-place concrete.

The minimum thickness of abutment parapets and wingwalls shall be 18 inches.

Shear lugs shall be used at each abutment as follows:

Bridges with curved superstructures

Straight bridges skewed more than 30 degrees with parapet abutments

Straight bridges skewed more than 30 degrees with semi-integral abutments

MSE walls shall not be constructed in front of bridge abutments.

For integral and semi-integral abutments, the dowel extending out of the end diaphragm into the approach panel shall be stainless steel.

Retaining walls shall not serve as abutments for bridges, except when properly designed cast-in-place concrete cantilever or counterfort/buttress wall types are used. Cast-in-place concrete cantilever or counterfort/buttress retaining walls may be used as wingwalls at abutments.

All piers for Bridge No. 62626 shall be designed and constructed as multi-column piers with crash struts to resist the 400-kip collision load specified in AASHTO LRFD Bridge Design Specifications, Article 3.6.5.

The Contractor shall not design bridges with the following:

Pile bent piers for permanent construction

Hollow piers

Integral pier caps

Splices in adjacent positive moment and negative moment reinforcement in pier caps shall be staggered. Splices in positive moment reinforcement shall be located in negative moment regions.

The Contractor shall provide slope protection for all areas where bridges prohibit growth of natural vegetation in accordance with the visual quality guidelines developed for the Project. Concrete slope paving shall be provided for bridges over roadways, trails, or Railroads. Riprap shall be provided under bridges over stream or lake crossings.
13.3.1.9 Barriers

The Contractor shall use the standard barrier details provided in MnDOT Bridge Details Manual Part II; however, the Contractor may use another barrier if it meets NCHRP Report 350 Crash Testing requirements and the visual quality requirements for the Project.

The height of bicycle railings shall not be less than 54 inches measured from the top of the riding surface.

Protective screening shall be continuous across the bridge and on the wingwalls.

Barriers shall not be included in determining the structural capacity of a bridge cross-section or the structural system.
13.3.1.10 Joints and Bearings

Uplift is not allowed.

13.3.1.11 Load Rating


The Contractor shall load rate all bridges carrying vehicular traffic. The Contractor shall provide the load rating using VIRTIS software. Guidelines for VIRTIS input requirements will be provided by MnDOT. If the bridge cannot be rated with VIRTIS, another commercially available structural analysis software shall be used with the Approval of MnDOT. The software shall be capable of running overweight vehicles as described herein.

The Contractor shall provide a rating manual for any bridge type that is not compatible with VIRTIS. This manual shall include methods that use influence lines and surfaces, instructions, and examples of how to rate the bridge for any type of future permit vehicle. A rating manual example will be provided by MnDOT upon request.

The Contractor shall complete a MnDOT Bridge Rating and Load Posting Report for each bridge on the Project. The VIRTIS software file shall be submitted with the MnDOT Bridge Rating and Load Posting Report. The ratings shall be based on the final configuration of the bridge.

The Contractor shall rate all bridges for LRFR using the following:

HL-93 loading

Minnesota Standard Permit Trucks G-80

Minnesota Standard Permit Trucks G-07 when VIRTIS is not used to load rate the bridge

The LRFR rating factor for bridges shall be a minimum of 1.0 at the Inventory level for HL-93 loading and 1.15 at the Operating level for permit loading.

The Contractor shall demonstrate that the minimum rating factors are being provided during the design of the bridge.

If VIRTIS software is not used, the Contractor shall rate all bridges, except concrete boxes, for LFR using the following:

HS-20 loading

Minnesota Standard Permit Trucks G-80

Minnesota Standard Permit Trucks G-07

For bridges with a minimum of one span over 200 feet long, the permit vehicle loading shall consist of a combination of the permit vehicle and lane load on any one lane of the bridge. The lane load shall be in accordance with Article 3.6.1.2.4 of the AASHTO LRFD Bridge Design Specifications, except the load shall be 0.20 klf.

Decks shall be rated for any design that deviates from MnDOT standard design tables.

Each separate superstructure component, segment, or type within the overall bridge shall be rated and reported; at a minimum, rate for moment and shear at the tenth points of each span.

The overall rating shall be the lowest rating of any individual component, segment, or type. The final rating and each component rating shall be accompanied by the location of the rating, the limit state, and the impact factor.

Where ramps extend onto a bridge, the ramp shall be rated as a separate member.

For culverts, MnDOT Form 90 shall be completed by the Contractor.

13.3.1.12 Additional Design Requirements

13.3.1.12.1 Maintenance and Inspection

All elements of bridge superstructures shall be accessible by ladder or an under-bridge inspection vehicle with a 75-foot arm.

The design and detailing of bridge joints and bearings shall include means for inspection and maintenance access and replacement.

Box girder bridges and other closed elements shall have an inside height of 4 feet or more, an inside width of 3 feet or more, and shall be made accessible for inspection during and after construction. Integral diaphragms shall be designed with an access hole of at least 3 feet wide by 3 feet high and shall be provided with ramps when the bottom of the opening is not flush with the walking surface.

Entrances to closed elements shall not be accessible to the public. Access doors shall swing into closed elements and shall be placed at locations that do not impact traffic under bridges. Access doors shall be accessible and lockable at both ends of the accessible portions of bridges. All locks for bridges shall be keyed alike with removable cylinders should re-keying be required.

Ventilation openings shall be installed for all confined spaces to accommodate a minimum air exchange rate of 6 times per hour.

All structural members shall have measures to prevent access of vermin and birds. All openings on bridges shall be enclosed and/or sealed off with screens to prevent access of vermin and birds.
13.3.1.12.2 Signs, Lighting, Signals, and Utilities

Conduits shall not be placed at the following locations:

Outboard side of box girders

Outboard side of precast concrete fascia beams

External face of substructures

Overhead lighting on bridges shall be located at bridge supports.
13.3.1.12.3 Bridge Grounding

All metal bridge elements above the deck shall be electrically grounded. Electrical grounding shall be in accordance with the applicable provisions of MnDOT Standard Specification 2557, the National Electrical Code, NEMA standards and any local electrical codes.
13.3.1.12.4 Approach Panels

Approach panels shall be cast-in-place.

13.3.2 Retaining Walls

13.3.2.1 Permanent Retaining Wall Structures

Permanent retaining wall types allowed are as follows:

Cast-in-place concrete walls

Soil nail walls

For design conditions outside the design parameters in the MnDOT Standard Plans Manual, cast-in-place concrete retaining walls shall be designed as either cantilever or counterfort/buttress retaining walls.

When proprietary or alternate wall systems other than cast-in-place concrete retaining walls are used, the Contractor shall provide site specifics to the wall provider in the roadway plans. Site specifics include: alignments, profiles, wall heights, loading conditions (e.g., dead loads and live loads), results of foundation investigations, water conditions, locations of all Utilities and drainage pipes (in-place, proposed, and future), site restrictions, expected wall cross-section, and desirable wall face treatments.

Except for at wing walls, the Contractor shall not intermix wall types within an uninterrupted wall segment. At wing walls, wall types can be intermixed if the retaining wall and adjacent wing wall have the same architectural treatment facing.

Cast-in-place concrete retaining walls shall be supported on driven piles or drilled shafts.

The Contractor shall design all retaining walls based on soil conditions found at the Site.

If the longitudinal slope of the footing becomes steeper than 1:10 (V:H), the Contractor shall use stepped footings.

Overall tolerances shall be within 0.5 inches in 10 feet. The total settlement of the foundation shall not exceed 1 inch.

Soil nail retaining wall design shall not include passive resistance of any earth in front of the retaining wall. The top 4.5 feet of soil shall be neglected in determining the passive resistance in front of cast-in-place concrete retaining walls.

Drainage for overland flow shall be provided at the top of retaining walls. Drainage shall also be provided at the bottom rear of the backfill or reinforced fill zone and at the bottom rear of the wall stem.

The Contractor shall not use Type I drainage systems for permanent retaining walls.

Slopes in front of retaining walls shall be 1:4 (V:H) or flatter.

When the end of a wall is exposed to approaching traffic within the clear zone area, the Contractor shall provide either a guardrail or crash cushion from MnDOT’s Approved Products and Certified Products list.

When the end of a wall is located in a gore area, the Contractor shall provide a crash cushion from MnDOT’s Approved Products and Certified Products list.

Soil nail retaining walls shall be protected by traffic barrier or guardrail when the wall face is within the clear zone or within 10 feet of the edge of pavement. The Contractor shall provide enough distance in front of the wall face to prevent any load transfer to the retaining wall upon impact and deflection of the traffic barrier or guardrail.

The Contractor shall provide traffic barriers that meet Test Level 4 requirements of NCHRP Report 350 on top of retaining walls under any of the following conditions:

The wall is within the roadway clear zone.

The wall is within 10 feet of the edge of pavement.

The wall constitutes a hazard to vehicles due to design speed, traffic volume, roadway geometrics, or any other applicable factors.

If a traffic barrier or guardrail is provided between the roadway and the top of retaining wall, the following shall apply:

A traffic barrier is not required on top of the retaining wall.

Fall protection is required at the top of the retaining wall for all retaining walls more than 3 feet high.

For walls accessible to pedestrians or maintenance personnel, one of the following types of protection shall be provided on top of the wall within 6 inches of the face of wall:

Pedestrian fencing

Pipe railing

Ornamental railing

The Contractor shall provide backfill for retaining walls meeting the requirements of MnDOT Standard Specification 3149.2B2 modified as follows: not more than 10 percent, by weight, of the portion passing the 1-inch sieve shall pass the #200 sieve. The backfill shall be compacted in accordance with MnDOT Standard Specification 2105.3F1.
The Contractor shall not use salvaged bituminous material or crushed concrete in the backfill.
13.3.2.1.1 Soil Nail Retaining Walls

Soil nail retaining walls shall not be used on bridge abutments, approach embankments, or in areas below the water table.

The Contractor shall provide Class I corrosion protection. Soil nails shall be fully encapsulated.

Figure 4.15c of FHWA Manual for Design and Construction Monitoring of Soil Nail Walls shall be used for the method of soil nail installation.

Soil nail strengths shall not exceed 72 ksi.

Soil nail lengths in vertical sections shall be uniform in the soil. Anchors shall not extend beyond the permanent Right of Way.

Self-drilling, self-grouting, and screw anchors are not allowed.

The allowable horizontal deflection at the top of the wall shall not exceed 0.5 percent of the wall height.

The design shall account for a frost depth of 4.5 feet.

Wall facings shall be constructed from cast-in-place concrete. The concrete mix designation shall be 3Y43. The minimum thickness shall be six inches.

Reinforcement in the entire anchorage assembly and cast-in-place concrete facing shall be epoxy coated per Mn/DOT Standard Specification 3301.

The Contractor shall submit for Approval a list of companies who will be performing the construction work and their experience with the construction of soil nail retaining walls.
13.3.2.2 Temporary Retaining Wall Structures

Temporary retaining walls shall be removed unless otherwise Approved by MnDOT. Temporary retaining walls left in place shall be identified on the As-built Documents and completely covered by soil or construction material as required per MnDOT Standard Specification 2442 so they are not visible. Temporary retaining wall structures constructed of treated timber shall not be buried and left in place. Structural components of temporary retaining walls may be reused as part of permanent retaining wall (two-phase walls) systems, provided all structural support elements and materials of the permanent retaining walls meet the requirements of permanent structure standards. Timber piles are allowed as foundations for temporary retaining walls.

13.3.3 Buried Structures


Buried structure types allowed are as follows:

Box culverts

Circular pipes

Three-sided precast concrete bridges

The Contractor shall not use long-span corrugated steel structures.

The Contractor shall use standard precast box culvert interior, headwall, and end sections included in the MnDOT Bridge Standard Plans Manual. For design conditions outside the design parameters on the standard precast box culvert drawings, the Contractor may use cast-in-place concrete interior, headwall, and end sections in accordance with the requirements stated in the MnDOT LRFD Bridge Design Manual.

For buried structures designed to provide a grade-separated crossing for pedestrian or bicycle traffic, the Contractor shall comply with the following:

Wrap the top and side joints on box culverts and all joints on precast concrete arches with waterproofing membrane system pursuant to MnDOT Standard Specification 2481.

Tie rod connections on the inside of the structure shall be recessed to prevent any element from projecting into the culvert.

Round head or countersunk bolt types shall be used at tie rod connections on the inside of the structure.

The Contractor shall use three-sided precast concrete bridges that are included on MnDOT’s Approved Product List.

Three-sided precast concrete bridges shall be designed and constructed with a skew of 0 degrees. Segments shall be supported on drilled shafts or piling.

Fall protection shall be installed around all openings when drops are greater than 3 feet and shall be mounted within 6 inches of the face.

13.3.4 Sign Structures


The Contractor shall design all cantilevered overhead sign structures for fatigue design loads, including galloping, natural wind gust, and truck-induced gusts.

The Contractor shall use drilled shafts or spread footings to support simple span and cantilevered overhead sign structures.

13.3.5 Lighting Structures


The Contractor shall design all high-level lighting structures for fatigue design loads, including vortex shedding and natural wind gusts.

The Contractor shall use drilled shafts or spread footings to support lighting and traffic signal structures.

13.3.6 Materials


The Contractor shall not use masonry, timber, or aluminum as materials for permanent bridge superstructures or substructures.

The Contractor shall not use timber or recycled material for permanent retaining walls.

The Contractor shall not use timber piles as foundations for permanent structures.

13.3.6.1 Concrete


The Contractor shall not use lightweight or self-consolidating concrete.

The Contractor shall comply with Section 8.3.9 (Concrete Mix Design) pertaining to concrete mix design options.

The minimum design compressive strength for cast-in-place structures shall be 4,000 psi, but shall not exceed 6,000 psi.

The minimum design compressive strength for precast concrete structures shall be 5,000 psi.

The design compressive strength for prestressed concrete beams shall not exceed 10,000 psi.

13.3.6.2 Prestressing Steel


Prestressed precast concrete beams shall use seven-wire, low-relaxation strands conforming to ASTM A416, Grade 270.

The minimum spacing for pre-tensioned prestressing steel shall be 2 inches.

13.3.6.3 Post-Tensioning Steel Systems


Post-tensioning steel systems shall comply with DBSB-2401.21 (Post-tensioning System).

13.3.6.4 Reinforcing Steel


See Standards.

13.3.6.5 Structural Steel


All structural steel shall conform to ASTM A709. The grade shall be as follows: Grade 50W, HPS50W, or HPS70W for flanges, webs, diaphragms, and stiffeners; and Grade 36 or Grade 50W for bearings and miscellaneous components.

All high strength bolts shall conform to ASTM A325, Type 3.

Non-high strength bolts shall conform to ASTM A307.

13.3.6.6 Timber


See Standards.

13.4 Construction Requirements

13.4.1 Structural Metals


The Contractor shall comply with MnDOT Standard Specification 2471 for fabrication of structural metals. The Contractor shall hold a pre-fabrication meeting at least two weeks prior to beginning shop and/or field fabrication. The Contractor’s quality control staff, the fabricator’s quality control staff, and MnDOT’s quality oversight staff shall attend the meeting to discuss fabrication method, materials, and documentation required under MnDOT Standard Specification 2471. All field and shop welding procedures shall be reviewed and Approved by a Minnesota-licensed Professional Engineer, not employed by the fabricator, who is knowledgeable with the specifications of American Welding Society as they apply to highway structures.

13.4.2 Field and Shop Painting of Structural Steel


Field and shop painting of structural steel shall be done by the Contractor in accordance with MnDOT Standard Specification 2478 or 2479, MnDOT Special Provisions, and AASHTO/NSBA Guide Specification for Application of Coating Systems with Zinc-Rich Primer. The top coat shall be applied on the outside web faces of the exterior girders and the bottom of all bottom flanges in the field.

The insides of steel box girders shall be painted with a two-coat system with primer and a top coat. The top coat shall be white.

Calibration of equipment and dry film thickness examinations shall be performed by the Contractor in accordance with Society for Protective Coatings (SSPC) PA2 (Measurement of Dry Coating Thickness with Magnetic Gages). Only National Transportation Product Evaluation Program (NTPEP) approved paint systems shall be used. Intermediate and topcoat paints shall be by the same manufacturer as the primer.

Testing by the Contractor for soluble salt contamination of steel to be repainted shall be concentrated in areas with coating failure, corrosion, or pitting. Readings greater than 10 parts per million of chlorides or nitrates per test area shall require the contaminated area represented by the test be recleaned and retested.

The Contractor performing shop application of a paint system shall be certified under the AISC Sophisticated Paint Endorsement or in accordance with SSPC QP3 (Standard Procedure for Evaluating Qualifications of Shop Painting Applicators). Contractors performing the removal and/or field application of a paint system shall have current certifications in accordance with SSPC-QP1 (Standard Procedure for Evaluating Painting Contractors – Field Application to Complex Industrial Structures) or SSPC-QP2 (Standard Procedure for the Qualification of Painting Contractors - Field Removal of Hazardous Coatings from Complex Structures).

13.4.3 Architectural Finish


If final concrete finishes are not applied prior to roadways being opened to traffic, the concrete shall be protected from snow and salt spray until finishes can be applied. Temporary surface protection shall be removed prior to applying concrete finish. High-pressure water blasting or sand blasting of the unfinished surfaces will be required where protection is not effective in protecting unfinished surfaces.

13.4.4 Bridge Superstructures


The Contractor shall satisfy the requirements of DBSB-2499 (SPMT Bridge Construction) for Bridge No. 62626. Temporary support locations that result in individual beam placement, deck construction, deck formwork removal, or barrier construction over traffic are not allowed. All formwork to build the bridge in the staging area shall be removed before bridge is moved to its permanent location.

For the bridge structural slab of Bridge No. 62626, the final finish texture shall be in accordance to the chip seal wearing course manufacturer’s recommendations. A roughened final finish texture is required if the bridge will be open to traffic prior to installing the chip seal wearing course. When checked with a 10-foot straightedge placed longitudinally thereon, the surface shall not vary from the straightedge more than 1/8 inch.

The Contractor shall meet the requirements of DBSB-2401.22 (Curing Bridge Slab) for curing bridge decks.

The Contractor shall maintain all waterproof expansion joints for a period of two months starting when public traffic is allowed to drive across the joint. The Contractor shall conduct a field leakage test at the end of the two-month period by flooding expansion joints with water. All damaged and leaking expansion joints shall be repaired or replaced. Prior to checking expansion joints for damage, the Contractor shall sweep the entire bridge deck, beginning a minimum of 50 feet before the bridge and concluding a minimum of 50 feet after the bridge.

13.4.5 Retaining Walls

Final retaining wall alignment shall be within 6 inches of that shown in the Contract Documents and shall be within 1 inch in 10 feet.

13.4.6 Bridge Removal


The removal limits for Bridge No. 6513 shall satisfy the requirements of Standard Specification 2442 at the end of construction of the Project and for the future cross-section as shown in Exhibit 11-D (Future Geometry).

13.5 Deliverables

13.5.1 Bridge Rating and Load Posting Report(s)


The Contractor shall submit the MnDOT Bridge Rating and Load Posting Report to MnDOT for Acceptance four weeks before the bridge is opened to vehicular traffic.

For culverts, MnDOT Form 90 shall be completed and submitted to MnDOT for Acceptance four weeks before the roadway over each culvert is opened to vehicular traffic.

When required, the Contractor shall submit a rating manual four weeks before the bridge is opened to vehicular traffic.




Addendum 3

Structures


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