C05 Attachment 12 Region 3-0310 Santa Fe National Forest - Encino LO.pdf

PDF 1 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 the Encino Lookout Tower, a 59-foot self-supporting structure located in Rio Arriba County, New Mexico (Region 03, Forest 10), prepared for the U.S. Forest Service by FAA Structural Support. The analysis, completed in January 2026, evaluates the tower's structural capacity to support existing technology and appurtenances using finite element modeling in accordance with TIA-222-H and ASCE-7-22 design standards. The tower achieved a PASS rating with a 76.35% capacity utilization, with diagonal components in the first section identified as the controlling element. The structure successfully meets deflection and twist requirements, with tilt and twist values of 0.64483 and 0.08242 degrees respectively, both below allowable limits of 1.3215 and 2.20244 degrees.

The tower consists of four sections constructed from equal angle leg steel members (L3×3×3/16 to L4×4×5/16), with wind speed design parameters of 104 mph at 9,800-foot elevation in a Class II Structure within Class C Exposure and Class 3 Topography. Analysis assumed rigid connections between tower sections and good working condition of all structural components and attached equipment, though foundation and soil capacities were not evaluated due to lack of design information. The report recommends verification of appurtenance functional performance, rechecking plumb and twist in the short term, and continued monitoring of tilt and twist measurements at intervals of at least once every five years to ensure ongoing structural integrity. All tower members passed individual capacity checks, with the highest utilization occurring in the lower diagonal members at 76.35%.

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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
C05 Attachment 11 Encino LO Structural Data.pdf	PDF	Nov 5, 2026
C05 Attachment 9 127EAX26Q0069 Pre-Bid Sign In Sheet.pdf	PDF	Nov 5, 2026
C05 Attachment 8 RFI Log 001-044.docx	DOCX document	Nov 5, 2026
C05 Attachment 13 031001L010201-Encino Lookout-20250513-C-TSIR-V16_01.pdf	PDF	Nov 5, 2026
C05 Attachment 14 031001L010201-Encino Lookout-20250513-SAR-LO-Data V1.1.pdf	PDF	Nov 5, 2026
C05 127EAX26Q0069 0002.pdf	PDF	Nov 5, 2026
C05 Attachment 17 031005L050501-Barillas Lookout-20230906-SAR-V9.pdf	PDF	Nov 5, 2026
C05 Attachment 16 031005L050501-Barillas Lookout-20230906-SAR-DATA-V9.pdf	PDF	Nov 5, 2026
C05 Attachment 7 WD NM20260011.pdf	PDF	Nov 5, 2026
C05 Attachment 10 CL-100_Plans.pdf	PDF	Nov 5, 2026
127EAX26Q0069 Amendment 00001.pdf	PDF	Oct 8, 2026
127EAX26Q0069 Amendment 00001 Provisions and Clauses.docx	DOCX document	Oct 8, 2026
C04 Attachment 5 WD NM20260028.pdf	PDF	Sep 11, 2026
C04 Attachment 4 Fire Plan and Guidelines.docx	DOCX document	Sep 11, 2026
C04 Attachment 2 Sched of Items.xlsx	XLSX spreadsheet	Sep 11, 2026
C04 Attachment 3 Specifications.pdf	PDF	Sep 11, 2026
C04 127EAX26Q0069.pdf	PDF	Sep 11, 2026
C04 Attachment 1 Statement of Work.pdf	PDF	Sep 11, 2026
C04 Attachment 6 WD NM20260026.pdf	PDF	Sep 11, 2026

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FAA Structural Support 8201 S. MacArthur Boulevard

Oklahoma City, OK 73169

Encino 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 – Encino Lookout Rio Arriba County, New Mexico

Latitude: 36°7'21.17"N, Longitude: 106°33'12.75"W

Report Date

Jan-2026

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

Oklahoma City, OK 73169

Encino Lookout Tower Page

Project

STRUCTURAL ANALYSIS

For

USFS

FAA-AJW-L500

Structural Analysis Report | REV 1.1

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

Oklahoma City, OK 73169

Encino Lookout Tower Page

Project

STRUCTURAL ANALYSIS

For

USFS

FAA-AJW-L500

Structural Analysis Report | REV 1.1

Tower Utilization with Current Configuration of Equipment/Structure PASS 76.35%

Summary:

o This structure is recognized as a Self-Support Lookout Tower.

o Lake Tower has a pass rating for the structure with the equipment currently installed.

o Tower has passed both the deflection and twist, as shown in the tower service results on (page 8) of the structure’s tilt & twist data.

o 76.35% capacity rating on the diagonal components located in the first section of the tower, as listed in the Tower Summary Information (p. 32).

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 on (page 32) for specific member information.

o Structural analysis results are generated on an assumed tower structural integrity of 100% of perfect condition with no known damage.

Oklahoma City, OK 73169

Encino Lookout Tower Page

Project

STRUCTURAL ANALYSIS

For

USFS

FAA-AJW-L500

Structural Analysis Report | REV 1.1

Executive Summary

The analyzed tower is approximately 59 feet Self-Support Lookout Tower constructed of 4 sections supporting existing technology and other assets attached at multiple heights on the tower. The tower is located near Rio Arriba 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 Rio Arriba County, New Mexico using a Type II Structure in a Class 3 Topography and Class C Exposure on a 9,800 FT elevation and 25 FT crest.

The Structural Analysis Report shows the Tower Rating of 76.35% (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.

Oklahoma City, OK 73169

Encino Lookout Tower Page

Project

STRUCTURAL ANALYSIS

For

USFS

FAA-AJW-L500

Structural Analysis Report | REV 1.1

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’s structure has been assessed for acceptable levels of twist, sway and deflection with the existing antennas and mounts attached. However, the foundation and soil haven’t been analyzed to determine their ability to 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

Oklahoma City, OK 73169

Encino Lookout Tower Page

Project

STRUCTURAL ANALYSIS

For

USFS

FAA-AJW-L500

Structural Analysis Report | REV 1.1

Basis of Design

The tower is a Self Support Lookout-type structure made up of 4 sections up to the top of the structure.

Each section is made of an Equal Angle leg section. The tower’s current condition information and tower data were formally recorded through onsite photography and field notes collected during the tower mapping, which were subsequently input into the data sheets either in the field or upon the technicians' return to their base of operations. 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 manufacturer 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.

Oklahoma City, OK 73169

Encino Lookout Tower Page

Project

STRUCTURAL ANALYSIS

For

USFS

FAA-AJW-L500

Structural Analysis Report | REV 1.1

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 OpenTower Designer® Version 10.03.01.03 (Bentley 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.

Oklahoma City, OK 73169

Encino Lookout Tower Page

Project

STRUCTURAL ANALYSIS

For

USFS

FAA-AJW-L500

Structural Analysis Report | REV 1.1

Results

The structural tower analysis yielded the following results:

Tower Strength Capacity Results Load Scenario Controlling Section &

Member Tower Rating

PASS / FAIL

Existing Diagonal (4) 76.35% PASS

Tower Service Results Load Scenario

Tilt - (DEG) Twist - (DEG) Tilt

PASS /

FAIL

Twist PASS /

FAIL ACTUAL ALLOWED ACTUAL ALLOWED

Existing 0 0 0 0 N/A N/A

0.64483 1.3215 0.08242 2.20244 PASS 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.

Oklahoma City, OK 73169

Encino Lookout Tower Page

Project

STRUCTURAL ANALYSIS

For

USFS

FAA-AJW-L500

Structural Analysis Report | REV 1.1

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.) Recheck the Plumb and Twist in short terms.

3.) Tower has passed both the deflection and twist, as shown in the tower service results. Continue to monitor the status of both the tilt & twist of the tower over the span of at least once every 5 years.

Oklahoma City, OK 73169

Encino Lookout Tower Page

Project

STRUCTURAL ANALYSIS

For

USFS

FAA-AJW-L500

Structural Analysis Report | REV 1.1

Appendix A - Detailed Analysis Graphics

Oklahoma City, OK 73169

Encino Lookout Tower Page

Project

STRUCTURAL ANALYSIS

For

USFS

FAA-AJW-L500

Structural Analysis Report | REV 1.1

Appendix B – OpenTower Output Report

Tower Profile

Shear (kip)Axial (kip)Moment (kip-ft)Load CombinationMaximum Reaction

Summary Tower Reaction

4.01219.3580C 12 - 1.2D + 1.0Wo-90°Compression

3.411-14.8810C 20 - 0.9D + 1.0Wo-90°Tension

4.01219.3580C 12 - 1.2D + 1.0Wo-90°Shear

11.04910.153384.897C 13 - 1.2D + 1.0Wo-135° Total Overturning Moment

(1.2D)

11.0497.615383.851C 21 - 0.9D + 1.0Wo-135° Total Overturning Moment

(0.9D)

3.8718.461136.878C 29 - 1.0D + 1.0Ws-135° Total Overturning Moment

(1.0D)

1.6412.93954.6527C 2 - 1.2D + 1.0Di + 1.0Wi-0°Total Compression

11.04910.153384.8967C 13 - 1.2D + 1.0Wo-135°Total Shear

Page 12 of 36OpenTower CE : 10.03.01.03Print Date:1/7/2026

Tower Summary

Scenario1Active Scenario

Longitude

Latitude

County

State

0 degBearing Angle with respect to North

0Base Elevation(ft)

59Tower Height (ft)

4-Leg Self-SupportingTower Type

Wind Load Parameters

9800Ground EL above Sea Level (ft)

0.25Ice Thickness (in)

40Ice Wind Speed (mph)

60Service Wind Speed (mph)

104Wind Speed (mph)

IIStructure Class

TIA-222-H (ASCE 7-16)-Annex SDesign Standard

Seismic Load Parameters

CSeismic Design Category

0.31317 seconds

0.12S₁

0.373

StiffSoilDefaultSite Class

3.0Response Modification Factor

1Importance Factor

IIRisk Category

Equivalent Lateral Force ProcedureMethod

TIA-222-H (ASCE 7-16)Design Standard

Analysis Parameters

LinearType of Analysis

Site Parameters

25 3 C II All

Crest

Height (ft)

Topographi c Category

Exposure