C05 Attachment 17 031005L050501-Barillas Lookout-20230906-SAR-V9.pdf

PDF 2 MB Posted Nov 5, 2026

Attached to: Barillas Peak & Encino Vista Lookout Tower Restoration, Santa Fe NF
Solicitation number: 127EAX26Q0069
Issued by: Department of Agriculture Forest Service

About this file

Written by GovTribe AI · Nov 5, 2026

This is a Feasibility Structural Analysis Report for a 54.4-foot self-support tower located near Santa Fe County, New Mexico, prepared by the Federal Aviation Administration (FAA) Structural Support Branch for the U.S. Forest Service (USFS). The analysis examines the structural adequacy of the existing tower supporting technology and appurtenances under current site-specific environmental loading conditions in accordance with ANSI/TIA-222-H and ASCE-7-22 design standards. The tower was modeled as a cantilever structure with five sections made of equal angle leg members, subject to wind loads of 105 mph basic wind speed and ice loads of 0.22 inches nominal thickness combined with 45 mph wind at the 9,202-foot elevation with 580-foot crest height. The structural analysis yielded a tower rating of 49.9% for existing physical conditions and current equipment configuration, indicating the tower structure passes all strength capacity requirements with controlling leg (T5) utilization at 49.9%. The analysis included service-level deflection calculations, foundation and soil capacity checks (not performed due to lack of design data), and comprehensive member capacity evaluations using finite element modeling via TNX Tower software. The report notes that all information not formally collected was derived from past experience and standard industry practice, and recommends verification of appurtenance functional performance and re-checking of plumb and twist in short intervals. An additional analysis scenario was run showing the tower would pass with two added antennas at the highest available position, though this does not justify proceeding with modifications without updated structural analysis.

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C05 Attachment 15 031005L050501-20221109-Barrillas Lookout-TSIR-Combined-v-13.8_01.pdf	PDF	Nov 5, 2026
C05 Attachment 2 Sched of Items - 127EAX26Q0069 R1.xlsx	XLSX spreadsheet	Nov 5, 2026
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C05 Attachment 16 031005L050501-Barillas Lookout-20230906-SAR-DATA-V9.pdf	PDF	Nov 5, 2026
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FAA Structural Support 8201 S. MacArthur Boulevard

Oklahoma City, OK 73169

Barrillas Lookout Tower

Page

Project

STRUCTURAL ANALYSIS

For

USFS

FAA-AJW-L500

Structural Analysis Report | REV 1.1

FEASIBILITY STRUCTURAL ANALYSIS REPORT

EXISTING STRUCTURE, TECHNOLOGY & OTHER ASSETS

FOR

U.S Forest Service

Tower Location

Region 03, Forest 10

New Mexico – Barillas Lookout Santa Fe County, California

Latitude: 35°34'7.75"N, Longitude: 105°28'24.13"W

Report Date

Jul-2024

Analysis and Report by:

Mohanad Ashor, EIT Civil Engineer

FAA Mike Moroney Air Logistics Center Oklahoma City, Oklahoma

Report Checked by:

Eric Trujillo Civil Engineer

FAA Mike Moroney Air Logistics Center Oklahoma City, Oklahoma

Project

STRUCTURAL ANALYSIS

For

USFS

Table of Contents Table of Contents Executive Summary Detailed Analysis Report Results Appendix A - Detailed Analysis Graphics Appendix B – TNX Output Report

Project

STRUCTURAL ANALYSIS

For

USFS

Executive Summary

The analyzed tower is approximately 54.4 feet Self Support Tower constructed of 5 sections supporting existing technology and other assets attached at multiple heights on the tower. The tower is located near Santa Fe County, New Mexico and supports operational and functional capacity of the sector. Tower has been identified for an update of the tower capacity. A full tower assessment has not been completed only the tower mapping and equipment inventory have been analyzed with current field notes which constitute the basis of the tower model and analysis.

All information not collected to complete the structural analysis will be derived from past experience, standard industry practice and other available information. Information not provided for incorporation into the structural analysis report will constitute a limiting factor for the operational (or functional) capacity of the tower structure.

Completion of a structural analysis does not constitute a verification of the operational degradation of existing technology, appurtenances, and other assets due to potential increases in deflection tilt or twist of the tower structure.

This information was used to determine the tower rating and safe load capacity for the tower in accordance with the provisions contained in ANSI/TIA-222, “Structural Standard for Antenna Supporting Structures and Antennas”. The tower was modeled with the currently recorded existing loading under the site-specific environmental loading for Santa Fe County, California using a Type II Structure in a Class 2 Topography and Class C Exposure on a 9202 FT elevation and 580 FT crest.

The Structural Analysis Report shows the Tower Rating of 49.9% (TIA-222-H, ASCE-7-22) for the existing physical condition of the tower and existing load configuration of attached assets and appurtenances. A tower rating exceeding 100% shows that a tower cannot accommodate the existing technology and other assets under the 222-H design standards.

For all future tower modifications, it is recommended that the tower regardless of rating receive an updated analysis to determine possible effects of the modification on the structure and existing equipment. This should be completed prior to modifications to include the addition or removal of equipment and/or structural components.

Tower Utilization with Current Configuration of Equipment/Structure 49.9% Notes:

o All other tower members are at or below the currently identified member with the highest utilization.

Modifications to the tower can both change the member with the highest utilization and greatly increase the percentage of utilization.

o See section capacity table for specific member information.

Tower Utilization with Updated Configuration of Equipment/Structure PASS Notes:

o Upon US Forest Service request, an additional structural analysis was run with two added antennas, (TeleWave ANT150F2) located at the highest available position. Results should be utilized to inform on the addition of new equipment to the tower, but not as justification to move forward with additions or modifications to the existing tower configuration. All additions or modifications should still receive a structural analysis to confirm the towers’ ability to accept the proposed modifications and/or equipment.

o Structural analysis results are generated on an assumed tower structural integrity of 95% of perfect condition with no known damaged.

Project

STRUCTURAL ANALYSIS

For

USFS

Detailed Analysis Report

Objective

Determine overall structural system adequacy for the existing load scenarios defined for the tower site.

Study Scope

FAA-AJW-L500 Structural Support Branch has completed a tower mapping and review of the current tower structure to do discrepancies with tower geometry among USFS service providers.

The analysis performed represents the estimated tower capacity and utilization to determine an overall Rating and Pass/Fail result for the adequacy of the tower structure. The tower was not analyzed to determine an acceptable level of twist, sway and deflection for microwave emitting dishes attached (existing) to the tower structure. Nor was the foundation and soil analyzed to determine safe load carrying capacity and utilization. The report for the tower at the above referenced site utilizes details and information from government furnished or collected information to construct the existing tower structure and site conditions. Government furnished or collected information has been referenced from tower mapping field notes and pictures. All information not provided or collected to complete the structural system analysis was derived from past experience, standard industry practice and other available information used from other comparable USFS Programs.

Applicable Codes, Standards and References

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STRUCTURAL ANALYSIS

For

USFS

Basis of Design

The tower is a Self Support-type structure made up of 5 sections up to top of the structure. Each section is made of a Equal Angle leg section. The tower’s current condition information and tower data was not formally recorded but can be seen from onsite photography and field notes collected during the tower mapping. The location, asset inventory and physical condition were noted and used to create the original structural analysis mode.

Data Document(s) Tower FAA Tower Mapping 2023 Loading FAA Tower Mapping 2023 Soil N/A Foundation N/A

Criteria, Assumptions and Input

Assumptions

The current documents do not identify enough information or data to provide all of the required input to complete the structural analysis of the tower. The following assumptions were required to complete the structural model;

1. Tower Locality Input (Reference Previous sections)

2. Tower sections rigidly connected at all connection and joints

3. Tower Coatings modeled through tower weight increases

4. Tower and Foundation were installed according to and within manufacturer specifications

5. Tower and Foundations were maintained in accordance with manufacturers specifications

6. Tower and Foundation are in good working order and condition

7. Appurtenances, mounts and technology installed in accordance with man. specifications

8. Appurtenances, mounts and technology able to withstand loading

9. Elevation reference center of antennas and attachment points for mounts.

10. Weights and surface areas of mounts, hardware, feedlines and other incidental assets are included in the weight and surface areas of the appurtenance and attachment unless otherwise modeled

Project

STRUCTURAL ANALYSIS

For

USFS

Limitations

1. Model may not accurately reflect designed tower and foundation due to construction eccentricities from craftsmanship and quality of materials incorporated into construction.

2. Model may not accurately reflect designed or constructed tower due to the maintenance and rehabilitation of the tower during the service life.

3. Model may not accurately affect actual condition of tower from exposure to non-static loading (i.e. dynamic loads or cyclical loads)

4. Model does not characterize or calculate factored loads on appurtenances, mounts and technology attached to tower for capacity results.

Input

The tower was loaded and modeled under existing loading and geometry noted in tower mapping and photography from 2023.

Analysis Method and Modeling

A three-dimensional finite element model of the tower in each scenario was created using TNX Tower® Version 8.2.4.3 (Tower Numeric Inc.). The model was used based on government furnished and collected information and the loading scenarios requested by USFS. The model was analyzed as a cantilever structure subject to wind and ice loads applied to all attached assets and appurtenances such as antennas, mounts, lightening protection, etc. normalized for site specific conditions. No additional environmental loads or miscellaneous construction eccentric loading was considered.

The tower was analyzed for linear first order effects to determine a failing elements and corresponding load capacities. Load capacities and failing elements are identified after the model is analyzed and calculated for the resulting forces, moments and stresses. Additional analysis is conducted to estimate non-linear and second order effects on the tower. The effect of displacement on the member forces (P-Δ effects) is included to identify potential overstressing or local buckling.

After completion of the linear and non-linear idealization of the model a comparison is made of the calculated member stresses with the allowable values set forth in the design standard. All elements and members that exceed the allowable stresses are identified as failing elements. The highest utilized member load capacity governed the overall rating for the tower.

Project

STRUCTURAL ANALYSIS

For

USFS

Results

The structural tower analysis yielded the following results:

Tower Strength Capacity Results Load Scenario Controlling Section &

Member Tower Rating

PASS / FAIL

Existing Leg (T5) 49.9% PASS

Tower Service Results Load Scenario Tilt - (DEG) Twist - (DEG) PASS / FAIL

ACTUAL ALLOWED ACTUAL ALLOWED

Existing 0 0 0 0 PASS

0.500744 0.190875 0.0040524 0.318125 PASS

0.430847 0.528263 0.0148713 0.562313 PASS

0.441135 0.842888 0.0206329 0.524375 PASS

Foundation Capacity Results Load Scenario Bending (KFT) Shear (K) PASS / FAIL

ACTUAL ALLOWED ACTUAL ALLOWED

Existing NOT CHECKED. FOUNDATION DESIGN NOT PROVIDED.

Soil Capacity Results Load Scenario Overturning (KFT) Bearing (KSF) PASS / FAIL

ACTUAL ALLOWED ACTUAL ALLOWED

Existing NOT CHECKED. GEOTECHNICAL INVESTIAGATION NOT PROVIDED.

Project

STRUCTURAL ANALYSIS

For

USFS

Conclusions

The structural system analysis produced the following conclusions:

• Tower Strength Capacity Results Pass

• Tower Service Results Pass

• Foundation Capacity Results Not Checked

• Soil Capacity Results Not Checked

Recommendations

The following items are recommended

1.) Verify the functional and operational performance of appurtenances and attachments.

2.) Re-check of Plump and Twist in short terms.

Project

STRUCTURAL ANALYSIS

For

USFS

Appendix A - Detailed Analysis Graphics

Project

STRUCTURAL ANALYSIS

For

USFS

Project

STRUCTURAL ANALYSIS

For

USFS

Project

STRUCTURAL ANALYSIS

For

USFS

Project

STRUCTURAL ANALYSIS

For

USFS

Appendix B – TNX Output Report

Tower Input Data

The main tower is a 4x free standing tower with an overall height of 54.40 ft above the ground line.

The base of the tower is set at an elevation of 0.00 ft above the ground line.

The face width of the tower is 13.33 ft at the top and 22.50 ft at the base.

This tower is designed using the TIA-222-H standard.

The following design criteria apply:

1. Tower is located in Santa Fe County, New Mexico.

2. Tower base elevation above sea level: 9202.00 ft.

3. Basic wind speed of 105 mph.

4. Risk Category II.

5. Exposure Category C.

6. Simplified Topographic Factor Procedure for wind speed-up calculations is used.

7. Topographic Category: 2.

8. Crest Height: 580.00 ft.

9. Nominal ice thickness of 0.2200 in.

10. Ice thickness is considered to increase with height.

11. Ice density of 56 pcf.

12. A wind speed of 45 mph is used in combination with ice.

13. Temperature drop of 50 °F.

14. Deflections calculated using a wind speed of 60 mph.

15. Weld together tower sections have flange connections..

16. Connections use galvanized A325 bolts, nuts and locking devices. Installation per TIA/EIA-222 and AISC

Specifications..

17. Tower members are ''hot dipped'' galvanized in accordance with ASTM A123 and ASTM A153 Standards..

18. Welds are fabricated with ER-70S-6 electrodes..

19. A non-linear (P-delta) analysis was used.

20. Pressures are calculated at each section.

21. Stress ratio used in tower member design is 1.

22. Local bending stresses due to climbing loads, feed line supports, and appurtenance mounts are not considered.

Options

Consider Moments - Legs Assume Legs Pinned √ Calculate Redundant Bracing Forces Consider Moments - Horizontals √ Assume Rigid Index Plate Ignore Redundant Members in FEA Consider Moments - Diagonals √ Use Clear Spans For Wind Area SR Leg Bolts Resist Compression Use Moment Magnification √ Use Clear Spans For KL/r √ All Leg Panels Have Same Allowable √ Use Code Stress Ratios Retension Guys To Initial Tension Offset Girt At Foundation √ Use Code Safety Factors - Guys √ Bypass Mast Stability Checks √ Consider Feed Line Torque Escalate Ice √ Use Azimuth Dish Coefficients √ Include Angle Block Shear Check Always Use Max Kz √ Project Wind Area of Appurtenances Use TIA-222-H Bracing Resist. Exemption Use Special Wind Profile √ Alternative Appurt. EPA Calculation Use TIA-222-H Tension Splice Exemption √ Include Bolts In Member Capacity Autocalc Torque Arm Areas Poles Leg Bolts Are At Top Of Section Add IBC .6D+W Combination Include Shear-Torsion Interaction √ Secondary Horizontal Braces Leg √ Sort Capacity Reports By Component Always Use Sub-Critical Flow Use Diamond Inner Bracing (4 Sided) √ Triangulate Diamond Inner Bracing Use Top Mounted Sockets √ SR Members Have Cut Ends Treat Feed Line Bundles As Cylinder Pole Without Linear Attachments √ SR Members Are Concentric Ignore KL/ry For 60 Deg. Angle Legs Pole With Shroud Or No Appurtenances Distribute Leg Loads As Uniform Use ASCE 10 X-Brace Ly Rules Outside and Inside Corner Radii Are Known

Project

STRUCTURAL ANALYSIS

For

USFS

Leg C Leg D

Fa ce

Face B

Face D

Square Tower

Face C

Wind 0

Wind 90

Wind

Leg A Leg B

Tower Section Geometry

Tower Section

Elevation ft

Assembly Database

Description Section Width

Number of

Sections

Length

T1 54.40-44.40 13.33 1 10.00 T2 44.40-34.40 15.02 1 10.00 T3 34.40-23.80 16.70 1 10.60 T4 23.80-12.50 18.49 1 11.30 T5 12.50-0.00 20.39 1 12.50

Tower Section Geometry (cont’d)

Diagonal Spacing

Bracing Type

Has K Brace

End Panels

Has Horizontals

Top Girt Offset in

Bottom Girt Offset

T1 54.40-44.40 10.00 K1 Down No Yes 0.0000 0.0000 T2 44.40-34.40 10.00 K1 Down No Yes 0.0000 0.0000 T3 34.40-23.80 10.60 K1 Down No Yes 0.0000 0.0000 T4 23.80-12.50 11.30 K1 Down No Yes 0.0000 0.0000 T5 12.50-0.00 12.50 K1 Down No Yes 0.0000 0.0000

Project

STRUCTURAL ANALYSIS

For

USFS

Leg Type

Size

Grade

T1 54.40-44.40 Equal Angle L3x3x1/4 A572-50 (50 ksi)

Double Angle 2L2 1/2x2x3/16 A572-50 (50 ksi)

T2 44.40-34.40 Equal Angle L3x3x1/4 A572-50 (50 ksi)

Double Angle 2L2 1/2x2x3/16 A572-50 (50 ksi)

T3 34.40-23.80 Equal Angle L3 1/2x3 1/2x1/4 A572-50 (50 ksi)

Double Angle 2L2 1/2x2x3/16 A572-50 (50 ksi)

T4 23.80-12.50 Equal Angle L4x4x1/4 A572-50 (50 ksi)

Double Angle 2L3x2 1/2x1/4 A572-50 (50 ksi)

T5 12.50-0.00 Equal Angle L4x4x1/4 A572-50 (50 ksi)