RCF PLATFORM TOWER Specs.doc

RCAG TOWER REPLACEMENT

February 5, 2019

JACKSON (JAN) RCAG

FAA-JAN-1602338

SECTION 13100 – ANTENNA TOWERS

PART 1 - GENERAL

1.1 SUMMARY

A.

This section includes the following

1. Design, and Fabrication of one 40 foot tall self supporting antenna tower

2. Design of the Tower Foundation

3. Erection of the Antenna Support Towers

4. Installation of RF Cable System

5. Installation of Tower Lightning Protection System and Grounding

B.

Related Sections and documents

1. Section 03305 – Cast in Place Concrete

2. Section 16000 - Electrical

1.2 REFERENCES

The current issues of the following documents in effect on the date of the invitation for bid form a part of this specification and are applicable to the extent specified herein.

FEDERAL SPECIFICATIONS

RR-G-661

Grating –Bar Type

OSHA 1910.25

Stairways

MILITARY SPECIFICATIONS

MIL-M-17194

Metal, Expanded, Steel

American Society For Testing And Materials (ASTM)

AMERICAN INSTITUTE OF STEEL CONSTRUCTION (AISC)SPECIFICATION

Standard Practice for Steel Buildings and Bridges.

AMERICAN IRON AND STEEL INSTITUTE

Cold-Formed Steel Design Manual

AMERICAN WELDING SOCIETY WELDING HANDBOOK

D1.1 Structural Welding Code

ELECTRONIC INDUSTRIES ASSOCIATION

TIA-222-G Structural Standards for Steel Antenna Towers and Structural Supporting Structures

AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI)

B18.22.1 Plain Washers

1.4 SUBMITTALS

1.4.1 Submittal Descriptions (SD)

Submittals are identified by SD numbers and titles as follows.

SD-02 Shop Drawings

Drawings, diagrams and schedules specifically prepared to illustrate some portion of the work.

SD-03 Product Data

Catalog cuts and brochures illustrating size, physical appearance and other characteristics of equipment.

SD-05 Design Data

Calculations, analyses or other data pertaining to a part of work.

1.4.2 Variations

When proposing a variation, deliver written request to the Contracting Officer, with documentation of the nature and features of the variation and why the variation is desirable and beneficial to Government. If lower cost is a benefit, also include an estimate of the cost saving. In addition to documentation required for variation, include the submittals required for the item. Clearly mark the proposed variation in all documentation. When delivering a variation for approval, Contractor warrants that this contract has been reviewed to establish that the variation, if incorporated, will be compatible with other elements of work.

1.4.3 Format of Submittals

1.4.3.1 Transmittal

Transmit each submittal to office of approving authority.

1.4.3.2 Format for SD-02 Shop Drawings

a. Shop drawings shall not be less than 8 1/2 by 11 inches nor more than 30 by 42 inches.

b. Include on each drawing the drawing title, number, date, and revision numbers and dates.

c. Dimension drawings; Identify materials and products for work shown.

1.4.3.3 Format of SD-03 Product Data

Indicate, by prominent notation, each product which is being submitted; indicate specification section number and paragraph number to which it pertains.

1.4.3.4 Format of SD-05 Design Data and SD-07 Certificates

Provide design data and certificates on 8 1/2 by 11 inches paper

1.4.5 Quantity of Submittals

Submit two copies of submittals for approval by the Contracting Officer.

1.4.6 Submittals Required

SD -02 Shop drawings

Tower design fabrication, foundation and erection drawings SD - 05 Design Data Tower structural design calculations

PART 2 - PRODUCTS

2.1 ANTENNA SUPPORT TOWER DESIGN

2.1.1 General

Each tower designed and furnished by the contractor shall be complete in accordance with all specification requirements including antenna supports, anchor bolts, safety rail, and all hardware essential for the erection of the tower. The contractor shall provide all materials supplies, equipment and services necessary to design, fabricate and prepare for delivery of all items listed in the contract schedule.

2.1.2 Tower Description

2.1.2.1 Four Leg Tower

The tower shall be a self-supporting steel structure with a platform at the top for mounting and servicing antennas. The tower shall be designed to be shipped knocked down and to be erected in the field using only structural bolts. The tower shall be fabricated in 20 foot plus or minus sections except that a 10 foot section shall be provided to obtain the required height( i.e. 30 or 50 feet ) The tower members shall be fabricated from pipe, angular or solid stock. The tower shall have 4 legs.

2.1.2.2 Support Arms and Antenna Mounts

The antennas will be installed on 2 ½ inch ID (2 7/8” OD) aluminum pipes that extend 36 inches above the top guard rail. The antenna support arms shall be spaced around the work platform to permit the installation of 12 antennas with 8 foot minimum separation. This can be accomplished with a rectangular platform with retractable antenna support arms in appropriate lengths and locations to provide the separation. The contractor shall submit designs for the antenna mount and its attachment to the tower.

2.1.2.3 Stairs

.The top of the tower shall be accessed by a staircase from the base of the tower. The staircase shall be designed to comply with OSHA 1910.25.

The staircase shall also meet the following FAA design requirements: 1) maximum staircase angle of 35 degrees and 2) All tower staircases shall have a guardrail installed 42” above the treads on both sides of the staircase in addition to the OSHA required handrail.

2.1.2.4 Work Platform and Guard Rails

The platform shall be fabricated of angle framing members and the floor of the platform shall be fabricated from either expanded metal grating or bar type grating. The minimum area for the work platform shall be 150 square feet less the area for the staircase. The floor shall be secured to the framing. The platform shall be provided with a guard rail composed of vertical posts with a top and intermediate rail located 42 inches and 23 inches respectively above the platform floor. A 4 inch high by 12 gauge toe board shall be secured to the inside of the guard rail posts located ¼” above the floor of the platform. The toe board shall run continuously around the perimeter. The perimeter framing members shall support the rails, toe board as well as the required antenna mounting brackets.

2.1.2.5 Work Platform Access

The staircase access shall be surrounded by a top and intermediate rail and toe board as specified in 2.1.2.4 and shall also have a self-closing gate installed at the top of the stairs.

2.1.2.6 Foundation

Two foundation designs shall be provided for the tower. One design shall be based on a safe soil, ultimate bearing pressure of 2000 pounds per square foot and one on a safe soil, ultimate bearing pressure of 4000 pounds per square foot. Concrete strength shall be based on a 28 day compressive strength of 3000 psi and a maximum slump of 4”. Reinforcing steel shall be intermediate grade billet ASTM A-615 grade 60 deformed bars. Foundation designs shall be oriented toward economical construction based on the costs of labor and materials at the time of the design.

2.1.3 Special Requirements

Unless otherwise indicated EIA Standard TIA-222-G shall govern the design and fabrication of the towers. The design shall be in accordance with AISC and AISI specifications and established engineering practices.

2.1.4 Service Conditions

Towers with a work platform, six stacked UHF/VHF standard communications antennas located atop the structure, with 3ea – 4” PVC Schedule 40 conduits on one side shall sustain the maximum stresses imposed by the following ambient conditions without permanent deformation damage or degradation to operations.

37°47'43.32"N 79°10'50.53"W Elevation is 4,057’ MSL

Wind borne sand and dust

250 lb concentrated load over any one sq ft

20 lb/ sq ft

Stairs 1,000 lb at any point on the stairs

Antenna Projected Area No Ice

2.46 square feet each

Antenna Projected Area 1/2” Radial Ice

3.55 square feet each

Junction box projected area – 12 sq. ft.

6 ea - 4 inch PVC conduits from the foundation to the tower platform

4 ea – ¾” lightning rod and down conductor mounted on a 2” diameter steel pipe extending 240 inches above the platform floor.

Two Junction Boxes – 50lbs each PVC Conduit - 1.98 lb/ft x 6ea = 11.88lb/ft of tower

(braced by the tower and is supported by the foundation)

2.1.5 Design requirements

2.1.5.1 Work Required

The contractor shall submit structural design calculations and design fabrication, foundation and erection drawings. All design calculations shall be indexed and arranged in and orderly manner with appropriate sketches so that any element may be easily identified. Complete structural calculations are required covering all parts of the structures and all related items. Tower twist, sway and displacement shall be determined by analytical method. All design loads shall be identified; design methods and assumptions indicated. When computer printouts form a portion of the design calculations, the contractor shall include all input diagrams and information needed to relate the printout to the design elements. The computer programs utilized shall be identified and a brief description of each shall be included. The submittal shall be certified by a Registered Professional Engineer.

2.1.5.1 Tower Drawings

The drawings shall include plan and elevation views antenna mounts grounding system and any pertinent notes. Erection drawings shall indicate member location, bolt sizes and number ladder attachment with safety climbing device, antenna mounts and all other information to clearly depict required elements for field erection a parts list showing the member size and length shall be provided in the erection drawings shall be provided for the installation of the obstruction light system.

2.1.5.1 Foundations Drawings

The foundation drawings shall include both plan and elevation views. Drawings shall include reinforcing bar size, quantity and position anchor bolt size and position and other pertinent information for the constructing the foundations and anchors.

2.2 MATERIALS

2.2.1 General

Unless otherwise indicated materials shall conform to the specifications and other requirements below. Where no specification is indicated the materials shall be of a good commercial quality suitable for the government s intended use and shall be subject the approval of the CO the contractor shall furnish all materials and items required that the complete structure an in addition shall furnish nuts, bolts and washers and other minor items in an amount 10% in excess of the quantity required for erection.

2.2.2 Tower Legs

The tower legs shall be fabricated of steel pipe , structural angles or plates. Steel pipe shall have a minimum yield strength of 33,000 lbs per square inch per ASTM A-53 or ASTM A-501. Structural angles or plates shall have a minimum yield strength of 36,000 lbs per square inch per ASTM A-36. Legs fabricated from steel having a minimum yield strength of 50,000 shall conform to ASTM A-618 grade 3 for pipe and ASTM A-242 for angles or plates

2.2.3 Tower braces

The tower braces shall be have a minimum yield strength of 33,000 lbs per square inch per ASTM A-53 or ASTM A-501. Structural angles or plates shall have a minimum yield strength of 36,000 lbs per square inch per ASTM A-36.

Horizontal angle members shall be supplied, that can be installed on any face of the tower and that are designed to support the 3 each conduits referenced in section 2.1.4 of this specification. The horizontal members may be no more than 5 feet apart in distance. The horizontal angle members shall be designed to allow grip strut or beam clamps to be attached directly to the horizontals for attaching the PVC conduit .

Tower braces shall be chamfered at a 45 degree angle the width of the angle member on the side that will not contact the tower leg to allow members on the inside of the tower legs proper clearance.

2.2.4 Base Section

The base section of all self supporting towers shall be fixed base utilizing load bearing plates drilled to receive anchor bolts cast into the foundation or it may be a short section or integral part of the first tower increment. If a separate base section is used it shall be cast into the foundation and similar in construction to the other tower increments. Base sections of guyed towers may be fixed base as above or hinged base with a load bearing assembly cast into the foundation or attached with anchor bolts cast into the foundation. Anchor bolts shall be furnished with the tower.

2.2.5 Bolts, Nuts and Washers

Bolts, Nuts and Washers, High Strength - Shall conform to ASTM A-325 or A-490.

Bolts, Nuts and Washers, Other Than High Strength - Shall conform to ASTM A-307 Grade A

Plain Washers Other Than Those in Contact With High Strength Bolt Heads and Nuts - Shall conform to ANSI B-18.22.1 Plain Washers Type B

Locknuts.- A jam nut shall be used on each bolt beneath the full nut . Self locking nuts intended for use on exterior bolted connections with any associated lock washers may be substituted for approval as a substitute for the regular nut and jam nut.

2.2.6 Grating

Expanded Metal Type: Military Specification MIL-M-17194

Bar Type: Federal Specification RR-G-661

Bearing Bars shall be aluminum alloy 6061-T6. Per ASTM B-221

Cross Rods shall be aluminum alloy 6063-T1. Per ASTM B-221

2.3 SAFETY TIE OFF ANCHORS

D-bolt Anchorages shall be integrated into the design so there is an anchorage within 6 feet of the outside railing where each antenna mount meets the top railing and at any location where the swing arm bracing is attached to the top rail.

2.4 FABRICATION

2.4.1 General

Fabrication shall be in accordance with the AISC specification. Members shall not have sharp edges which would be hazardous during handling or other irregularities that would interfere with erection. Welding shall conform to the AWS structural welding code.

2.4.2 Stamping

Each separate member except bolts, washers, etc shall be clearly marked by stamping into the steel the part number shown on the drawings. All parts shall be marked in the same relative position. The mark shall be stamped in the steel before galvanizing and shall be clearly visible in the erected structure. Each piece shall be marked with one inch high letter/number combination.

2.5 FINISHES

Galvanizing – All ferrous parts shall be hot dipped galvanized after fabrication in conformance with ASTM A-123 and A-385. Hardware nuts bolts washers and other minor items shall be galvanized by the hot dip method in conformance with ASTM A-153 The projection portions of anchor bolts plus 12 inches shall be galvanized. The interior of all pipe shall be galvanized.

PART 3 EXECUTION

3.1 PREPARATION FOR DELIVERY

The complete system will be packed to insure carrier acceptance and safe delivery at the destination in containers complying with rules and regulations applicable to the mode of transportation

3.2 FIELD QUALITY CONTROL

Quality control shall be in accordance with the American Institute of Steel Construction Specification. All tests and inspections to determine compliance shall be made by the contractor and shall be subject to Government observation or verification. Contractor shall notify the CO five (5) days in advance of the delivery to allow a government representative to inspect the towers upon delivery.

3.3 REPLACEMENT OF DAMAGED OR MISSING PARTS.

Any damaged or missing parts noted at the time of the delivery inspection shall be replaced at no cost to the government. Parts damaged after the acceptance of the shipment shall, when requested, be replaced by the fabricator at a reasonable cost and time schedule.

3.4 ERECTION INSTALLATION

Construction procedures and erection sequence shall be consistent with the plans and specifications and shall be designed to result in safe and expeditious completion of the work. Any method of erection which results in permanent deformation or warpage of members will be disallowed. Refer to shop drawings furnished with tower.

All anchor bolt locations and base elevations shall be carefully checked and any errors reported to the Government Representative.

True alignment must be maintained as the work progresses and on completion the tower shall be plumb and true. If the error in alignment and true shape does not exceed 1 part in 200, the structure will be considered in alignment.

All required bolts and fasteners shall be installed and on completion of the structure shall be tight when structural alignment is attained

Normally, nuts will be to the outside of vertical members and on the bottom of horizontal members.

Lock nuts, where required, shall be properly installed.

Members which have suffered damage shall be repaired to “as new” condition before use in the structure. The Contractor shall repair minor damage. Damage to Government furnished material not considered minor shall be immediately reported to the Government Representative and repairs made as directed. Field welding, unless shown on the drawings, will not be permitted without the approval of the Government Representative.

3.5 CONSTRUCTION

3.5.1 Grounding New Tower

Except as otherwise provided on the drawings, at least two legs of the tower shall be grounded by ten-foot ground rods connected to the tower with a minimum #4/0 bare copper wire. Wire shall be exothermically welded to the ground rod below grade and Cadwelded to the antenna tower legs 24 inches above the finished surface of the tower foundation. The ground wire shall be protected by a PVC conduit, in the footing. The ground wires shall be connected to the facility grounding system with the 4/0 BSDC counterpoise to be installed with the coaxial cables as specified elsewhere. Refer to drawings.

3.5.2 Lightning Protection

Lightning protection system for new tower shall be furnished and installed as shown on the contract drawings. Two 4/0 BSDC grounds shall also be installed from the perimeter counterpoise through the foundation and into the fiberglass junction boxes at the base of each antenna tower. The PVC conduit through the foundation shall be extended up into the junction boxes. Leave 36 inches of 4/0 BSDC in each box to be terminated by others.

3.5.3 Cable Installation

Contractor shall install 14 runs of Government furnished 7/8” Andrew AVA5-50 heliax cable from inside of building, to base of tower, thence up tower to junction box on top of tower. Cable ends shall at all times be protected from the weather and sharp bends in cable shall be avoided. Cable shall be installed inside Government-furnished junction box as shown on the drawings. Coaxial cable shall be run in six 4” diameter schedule 40 PVC conduits and the conduit attached to the antenna tower by stainless steel unistrut supports as shown on the drawings. All hardware shall be stainless steel as per the drawings.

3.6 PROTECTION

Upon completion of assembly of tower, but before erection, any and all areas which have had the galvanized finish damaged or otherwise abraded, shall be thoroughly cleaned and sprayed with two coats of cold galvanized spray.

END OF SECTION 13100

ANTENNA TOWERS

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