HStreet-Book 2-Sec 13 Structures_Add5 Legion

H Street/Benning Road Streetcar Implementation Design-Build Project District Department of Transportation Book 2 – Technical Requirements

Structures Addendum 45 Page 1 of 11

13 STRUCTURES

13.1 General The Contractor shall conduct all Work necessary to meet the requirements associated with permanent and temporary structures and modifications to existing structures, including bridges, retaining walls, barriers, box culverts, sign structures, slabs on grade, maintenance facility structures, miscellaneous structures, and lighting structures.

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. All standards shall be the latest edition or revision as of issuance of Request for Proposals, unless noted otherwise.

13.2.1.1 Bridges • DDOT Standard Specifications for Highways and Structures

• DDOT Design and Engineering Manual

• DDOT Standard Drawings

• AASHTO LRFD Bridge Design Specifications (for all new work except as outlined below)

• AASHTO Standard Specifications for Highway Bridges, 17th Edition (for re-use design of piers and footings, bridge girders, and bridge deck modifications)

• AASHTO LRFD Bridge Construction Specifications

• AASHTO Guide Design Specifications for Bridge Temporary Works

• AASHTO Construction Handbook for Bridge Temporary Works

• AASHTO Guide Specifications for Design of Pedestrian Bridges

• AASHTO Manual for Condition Evaluation and Load and Resistance Factor Rating (LRFR) of Highway Bridges

• AASHTO/NSBA Steel Bridge Fabrication Guide Specification

• AASHTO/NSBA Guide Specification for Application of Coating Systems with Zinc-Rich Primers to Steel Bridges, S 8.1

• FHWA Post-Tensioning Tendon Installation and Grouting Manual

• Post-Tensioning Institute (PTI) Acceptance Standards for Post-Tensioning Systems

• CEB-FIP Model Code for Concrete Structures (for time-dependent behavior of concrete) *

• American Railway Engineering and Maintenance-of-Way Association (AREMA) Manual for Railway Engineering

• WMATA TRAM/LRT Guideline Design Criteria

• WMATA Adjacent Construction Project Manual



• Remaining standards set forth in Book 3

* The Contractor may use the CEB-FIP Model Code for Concrete Structures in lieu of the AASHTO LRFD Bridge Design Specifications approximate methods.

13.2.1.2 Retaining Walls • DDOT Standard Specifications for Highways and Structures


• AASHTO LRFD Bridge Design Specifications


• AASHTO Standard Specifications for Highway Bridges, 17th Edition

• AASHTO Guide Design Specifications for Bridge Temporary Works

• AASHTO Construction Handbook for Bridge Temporary Works

• FHWA Mechanically Stabilized Earth Walls and Reinforced Soil Slopes Design and Construction Guidelines

• FHWA Corrosion/Degradation of Soil Reinforcements for Mechanically Stabilized Earth Walls and Reinforced Soil Slopes

• 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 & Construction Monitoring of Soil Nail Walls


13.2.1.3 Box Culverts • DDOT Standard Specifications for Highways and Structures


• AASHTO LRFD Bridge Design Specifications



13.2.1.4 Sign Structures • DDOT Standard Specifications for Highways and Structures


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


13.2.1.5 Lighting Structures • DDOT Standard Specifications for Highways and Structures




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


13.2.1.6 Buildings or Architectural Structures • District of Columbia Municipal Regulations

• ACI Building Code Requirements for Structural Concrete (318-08) and Commentary

• AISC Steel Construction Manual


13.2.2 Meetings See Standards.

13.2.3 Software See Standards.

13.3 Technical Requirements

13.3.1 Project Elements The Contractor shall provide all Work, temporary, permanent or rehabilitation, to provide the following Project elements, at a minimum:

13.3.1.1 Retaining Walls Not used

13.3.1.2 Streetcar Access Doors and Openings Not used

13.3.1.2.1 Access Doors West of First Street NE Not used

13.3.1.2.2 Access Doors East of First Street NE Not used

13.3.1.2.3 Maintenance Facility Access Doors

Not used

13.3.1.2.4 Access Door East of First Street NE Platform

Not used

13.3.1.2.5 Access Door West of Second Street NE



Not used

13.3.1.2.6 Access Opening East of Second Street NE Not used

13.3.1.3 Existing Elements Not used

13.3.1.4 Hopscotch Bridge – Girders, Deck and Approach Not used

13.3.1.5 Hopscotch Bridge – Pier 1

Not used

13.3.1.6 Hopscotch Bridge – Abutment 1 Not used

13.3.2 Bridge Load Rating Not used

13.3.3 Design Parameters

13.3.3.1 Loads and Forces The Contractor shall use the following live loads for design with special provisions as noted below.

• Vehicular live loads for structural design shall include the following:

– For design of all new construction: HL-93 with dynamic load allowance (AASHTO LRFD Bridge Design Specifications Article 3.6.1.2.1)

– For evaluation of existing foundations supporting new superstructures and for deck slab modifications: HS20 with Impact (AASHTO Standard Specifications for Highway Bridges, 17th Edition, Article 3.7)

– Streetcar vehicle: Four 21.5-kip axle loads spaced at 6.17 feet, 32.54 feet, and 6.17 feet. The LRFD Strength II Limit State Load Combination shall be used in lieu of the Strength I Limit State for the Streetcar vehicle

• Pedestrian live loads for structural design shall include the following:

– Pedestrian loading on sidewalks: For design of all new construction, 75 psf (AASHTO LRFD Bridge Design Specifications Article 3.6.1.6). For evaluation of existing foundations supporting new superstructures, load per square foot shall be evaluated per AASHTO Standard Specifications for Highway Bridges, 17th Edition, Article 3.14.1).

– Pedestrian Bridges: 85 psf (AASHTO LRFD Bridge Design Specifications Article 3.6.1.6).

13.3.3.2 Design Method The Contractor shall develop a Corrosion Protection Plan that includes the following:

• The Contractor’s approach to assuring a 75-year service life for the structural elements of the Project.



• The process for determining material selection.

• Estimates of life-cycle costs.

• Detailed provisions for reinforcing steel and structural steel protection.

• Assessment of the effects of concrete permeability, corrosion thresholds, corrosion rate, impacts on cracked concrete, and time to repair.

• Recommendations on the use of calcium nitrite or silica fume, sealers, membranes, reinforcing coatings, increased concrete cover, corrosion inhibitors, and other applicable methods.

Cathodic protection is not required.

13.3.3.3 Appurtenances The Contractor shall design to appropriate standards all connections of miscellaneous items, such as utilities and catenary, to proposed or existing structures.

13.3.4 Additional Design Requirements 13.3.4.1 Geometrics The Contractor shall locate substructure elements and retaining walls to avoid impacts to Utilities and other subsurface items or coordinate their relocation. Utility relocation activities, if necessary for substructure construction, shall be accounted for in the Contract Schedules.

13.3.4.2 Components 1. General

Fracture-critical components will not be allowed.

13.3.4.3 Retaining Walls

13.3.4.3.1 Permanent Retaining Wall Structures The Contractor shall determine the location(s) and types of retaining walls needed on the Project to meet the requirements of the Contract Documents.

Permanent retaining wall types allowed are as follows:

• Cast-in-place concrete walls

• Precast concrete walls

• Drilled shaft tangent retaining walls

• Soil nail walls

• Soldier pile/post-and-panel walls

• MSE walls

• Modular block walls

• Drilled shaft walls

The Contractor shall not use steel sheet pile, timber, or recycled material for permanent retaining walls or retaining wall foundations.



The Contractor shall not change or intermix wall types within an uninterrupted wall segment.

Cast-in-place concrete retaining walls shall be supported on spread footings, driven piles, or drilled shafts. Base leveling pads of concrete, crushed stone, or other manufacturer-recommended material shall be installed for proprietary or alternate wall systems when required.

Drainage for overland flow shall be provided at the top of retaining wall systems. Drainage shall also be provided within the wall system at the bottom rear of the backfill or reinforced fill zone and at the bottom rear of the front face or leveling pad of the wall.

Overall tolerances shall be within 1/2 inch in 10 feet. The settlement of the foundation soils and structure shall not exceed 1 inch after installation of associated bridge foundations and paving.

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

When steps in the horizontal alignment are used in the wall design, the steps shall face away from traffic. Points of inflection in the horizontal alignment of retaining walls with the wall face angling toward or away from traffic are acceptable.

The Contractor shall provide traffic barriers in front of retaining walls when the wall faces are within the clear zone of a roadway. When guardrail is used, the Contractor shall provide enough distance between the guardrail and wall to absorb the design deflection.

When the end of a wall is exposed to approaching traffic within the clear zone, the wall shall be considered a fixed object, and the Contractor shall provide either a guardrail or impact attenuator as protection.

Impact attenuators located at the ends of walls in gore areas shall be Quad Beam Impact Attenuators as specified in Standard Specification 627.

The steepest slope in front of a retaining wall shall be 1:4 (V:H).

The Contractor shall provide traffic parapets on top of retaining walls under any of the following conditions:

• The top of wall is within the roadway clear zone

• The top of wall is within 10 feet of the edge of roadway

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

If a traffic barrier or guard rail is provided between the roadway and the top of retaining wall, a traffic barrier is not required on top of the retaining wall.

For all walls accessible to pedestrians, pedestrian fencing shall be provided within 6 inches of the face of wall and on top of the wall.

The Contractor shall meet the following requirements for each specialty retaining wall structure type:

Drilled Shaft Tangent Retaining Walls

• Not allowed for use on bridge abutments or approach embankments.

• Corrosion protection shall be for a 100-year design life.



• Allowable horizontal deflection at the top of the wall shall not exceed 0.5 percent of the wall height.

• Contractor shall address and detail freeze/thaw issues due to moisture behind the wall facing.

• The design shall account for a frost depth of 2.5 feet.

• Wall facings shall be cast-in-place concrete.

• Minimum wall thickness shall be 6 inches.

• Reinforcing steel shall be epoxy coated.

• The Contractor shall provide DDOT a list of companies who will be performing the construction work details on their experience constructing these wall types.

Soil Nail Retaining Walls

• Not allowed in areas below the water table.


• Level 1 corrosion protection is required. Soil nails shall be fully encapsulated.

• Figure 4.15c, FHWA SA-96-069R, page 145, shall be used for the method of soil nail installation.

• Soil nail strengths shall not be assumed to be greater than 72 ksi.

• Soil nail lengths in any vertical section shall be uniform.

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


• The Contractor shall address and detail freeze/thaw issues due to moisture behind the wall facing.




• Reinforcement in the entire anchorage assembly and cast-in-place concrete facing shall be epoxy coated.

• Anchors shall not extend beyond the permanent Right-of-Way.

Soldier Pile/Post-And-Panel Retaining Walls


• Corrosion protection shall be for a 100-year design life.

• Contractor shall address the issue of larger steel sections and sacrificial steel for the soldier pile.




• Timber used for temporary lagging shall not be treated.

• Contractor shall address and detail freeze/thaw issues due to moisture behind the wall facing.


• When soldier piles are required to penetrate rock, the pile shaft shall be drilled and encased with concrete.

• All pre-drilled pile shafts shall be encased in concrete.



• Reinforcing steel shall be epoxy coated.

• Level 1 corrosion protection shall be provided for all anchors. Anchors shall be fully encapsulated.

• Anchors shall not extend beyond the permanent Right-of-Way limits.

Mechanically Stabilized Earth (MSE) Retaining Walls


• If an MSE Wall abuts a cast-in-place bridge abutment, the Contractor shall submit a joint design and detail for Approval by DDOT. No butt joints shall be allowed at these locations. Joints shall be designed such that there will be no leakage of backfill material.

• If an MSE wall abuts a cast-in-place bridge abutment, the front face of the wall shall be flush with the face of the abutment.

• The Contractor shall provide details for sealing any penetrations to the impervious geomembrane during construction. Care shall be taken by the Contractor to protect the impervious geomembrane during construction.

• The Contractor shall design joints where the traffic barrier meets the approach slab to prevent the drainage of surface water into the reinforced soil zone

• No MSE retaining walls will be permitted where temporary or permanent Utilities are within the reinforced earth zone.

13.3.4.3.2 Temporary Retaining Wall Structures All temporary retaining walls shall be completely removed prior to completion of the Project. Structural components of temporary retaining walls may be reused as part of permanent retaining wall (two-phase wall) systems, provided all structural support elements and materials of the temporary retaining walls meet the requirements of permanent structures. Timber piles may be used as foundations for temporary retaining walls.

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

The Contractor shall use drilled shafts or spread footings to support overhead and cantilever sign structures and sign supports.



13.3.4.5 Lighting Structures The Contractor shall design all high-level lighting structures for the fatigue design loads, including vortex shedding and natural wind gust.

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

13.3.5 Materials 13.3.5.1 Concrete The use of lightweight concrete is acceptable upon Approval by DDOT.

Prestressed Concrete The release and final strengths shall be determined by the Contractor. The design compressive strength shall be limited to 10,000 psi.

Substructure Concrete The minimum concrete strength shall be 4,500 psi.

Precast Concrete The minimum concrete strength shall be 4,500 psi.

Concrete Mix Design Options The Contractor shall comply with DDOT Standard Specification Section 817 pertaining to concrete mix design options.

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

The minimum spacing for prestressing strands shall be 2 inches.

The allowable stresses shall be in accordance to the AASHTO LRFD Bridge Design Specifications and the following:

• Concrete tension at Service Limit state before losses: 0.0948(fci’)0.5≤0.2 ksi

• Concrete tension at Service Limit state after losses: 0.0948(fc’)0.5

13.3.5.3 Post-Tensioning Steel Systems See Standards.

13.3.5.4 Reinforcing Steel See Standards.

13.3.5.5 Structural Steel All structural steel shall meet Section 815 of the Specifications except that all new structural steel for bridge or structural members shall conform to ASTM A709. The required grade of steel shall be per the Contractor’s design.



The Contractor shall not use ASTM A490 bolts.

All high-strength bolts shall conform to ASTM A325, Type 1 for painted connections and Type 3 for unpainted weathering steel connections.

Non-high-strength bolts shall conform to ASTM A307.

13.3.5.6 Timber See Standards.

13.3.6 Field and Shop Painting of Structural Steel Field and shop painting of structural steel shall be done by the Contractor in accordance with the AASHTO/NSBA Guide Specification for Coating Systems with Inorganic Zinc-Rich Primer, S 8.1-2002 The coating system details shall be coordinated with the Corrosion Protection Plan. 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.

Calibration of equipment and dry film thickness examinations shall be performed by the Contractor in accordance with the Society for Protective Coatings (SSPC) PA2 (Measurement of Dry Film Thickness with Magnetic Gages). Only paint systems approved by National Transportation Product Evaluation Program (NTPEP) 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 Contractors). 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 Evaluating the Qualifications of Painting Contractors to Remove Hazardous Paint).

13.3.7 Structural Metals The Contractor shall comply with DDOT Standard Specification 815 for fabrication of structural metals except as noted herein. 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 DDOT’s quality oversight staff shall attend the meeting to discuss fabrication method, materials, and documentation required.

13.3.8 Bracing Temporary bracing shall be provided as needed during construction in accordance with the AASHTO Guide Specifications for Bridge Temporary Works and the AASHTO Construction Handbook for Bridge Temporary Works.



13.3.9 Architectural Finish All strucutral elements shall be finished per the requirments of the Approved Visual Quality Management Plan.

13.3.10 Construction Requirements Not used

13.4 Deliverables Unless otherwise indicated, all deliverables shall be submitted in both electronic format and hardcopy format. Acceptable electronic formats include Microsoft Word, Microsoft Excel, or Adobe Acrobat (PDF) files. At a minimum, the Contractor shall submit the following to DDOT:

Deliverable For Approval

Number of Copies Submittal Schedule Reference

Section Hardcopy Electronic

Corrosion Protection Plan 5 1

Prior to submittal of any Released for Construction

Documents 13.3.3.2