A04_100__Statement_of_work_PedestrianBridges.docx

Statement of Work Water Canyon Trail Bridges

1.0 Overview

· The Bureau of Land Management (BLM), Winnemucca District Office has the requirement for two pre-manufactured steel pedestrian bridges and precast abutments for bridges. The contract will include AASHTO structurally designed self-weathering steel pedestrian bridges, concrete abutments, and anchor bolts with delivery to BLM project site located near Winnemucca, NV.

2.0 Materials

a. Unpainted Weathering Steel shall be fabricated from high strength, low alloy, and atmospheric corrosion resistant ASTM A847 cold-formed welded square and rectangular tubing and/or ASTM A588, ASTM A242, or ASTM A606 plate and structural steel shapes. Steel shall have a minimum yield strength of 50ksi. The minimum corrosion index of atmospheric corrosion resistant steel, as determined in accordance with ASTM G101, shall be 6.0. The minimum thickness of all structural steel members shall be three-sixteenths of an inch (3/16”) nominal and be in accordance with AISC Manual of Steel Construction “Standard Mill Practice Guidelines.” For ASTM 500 and ASTIM A847 tubing, the section properties used for design shall be per the Steel Tube Institute of North America, Hollow Structural Sections, “Dimensions and Selection Properties.”

b. Bolts Field splices shall be fully bolted with ASTM A325 high strength bolts in accordance with AASHTO specifications for structural joints.

c. Deck Decking shall be one of the following:

1. Douglas Fir No. 1 or Southern Pine No. 1 Structural (1000# minimum extreme fiber bending) Grade or approved equal. Wood decking shall have a minimum CCA (Copper Chromium Arsenate) content equal to .40 pounds per cubic foot or approved equal. All wood shall comply with American Softwood Lumber Standard PS-20-70. Each piece of lumber shall be identified by the grade and treatment mark. All lumber specified for treatment shall be treated to the requirements of American Wood Preservers Bureau AWPB LP-22.

2. Synthetic artificial material that mimics natural wood. Color shall conform to the BLM Standard Environmental Colors Chart.

3.0 Bridge and Design Requirements

· Structural Design Requirements

· Frost depth – 24 inches

· Live load – 90PSF

· Ground snow load – 5PSF

· Wind – 90 MPH w/115MPH gust

· Exposure - C

· Seismic zone – D1

· Railing – 50 PLF Rail Live Load, 200 lb. point load

· Provide structural drawings including abutment design and anchor bolt design for each bridge. Drawings provided in the contract documents are for bidding purposes only.

· The upstream bridge spans 60’ and the downstream bridge spans 45’

· Each bridge shall have 4’ clear width. The width shall be the clear width to structural members (or handrails if provided).

· Pratt or Howe style truss with one diagonal per panel and square ended vertical members.

· Railing shall be a minimum 42” above the deck surface and a maximum of 54” above the deck surface. Railing shall conform to the International building code (IBC) and ADA Standards for Accessible Design.

· Each of the bridge abutments shall be placed at the same elevation on both ends.

4.0 Abutment and Anchor Design Requirements

· Abutment foundations shall be designed to support all forces transferred from the bridge.

· Structure can be supported by conventional strip and/or spread footing.

· Provide abutment designs for each bridge. Minimum 28-day strength for the abutment concrete shall be 4,000 PSI. Attached drawings show the channel size and riprap with proposed slopes and bridge elevation/bearing seat elevations. Foundations shall be semi-retaining to depth required for bank slopes shown on drawings.

· The anchor bolts shall be designed to resist all horizontal and uplift forces to be transferred by the superstructure to the supporting foundations.

5.0 Warranty Requirements

· Provide industry standard commercial warranty at a minimum of 10 years for all steel components.

6.0 Delivery Requirements

· Period of performance: Fall 2023, after peak wildfire season and when Whites Creek is at low flow.

· Each bridge must be delivered as one solid steel component. Decking and other accessories may come separate if they are packaged for outdoor storage and movable with a forklift.

· Due to the nature of the project, weather conditions at the project location, manufacturing time, and availability of crane contractor delivery may be delayed and/or scheduled later. Coordinate with BLM for delivery.

7.0 Submittals

· Bidders shall provide a detailed, itemized quote for all bid items (bridges, shipping, precast abutments with drawings and calculations)

· Bidders shall submit preliminary drawings and specifications showing all items addressed in this statement of work

· Once awarded manufacture is to provide finalized structural drawings, specifications and complete design structural calculations with references for the superstructure, abutments and anchor bolts. Structural calculations and drawings must be signed by a Professional Engineer licensed in the State of Nevada.

· Operation and maintenance manual, installation instructions and warranty documentation.