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INSTRUCTORS:
Gary L. Seider, P.E., M.ASCE
Peter Kandaris P.E.
J.T. McGinnis, P.E., G.E., P.Eng
Keith S. Yamatani, P.E.
Brittany Huntsberger, P.E.
Purpose and Background
These presentations were recorded at the Electrical Transmission & Substation Structures Conference 2025.
Effect of Spacing on the Capacity of Helical Guy Anchors (23 minutes)
This presentation examines how horizontal spacing between helical guy anchors affects overall uplift capacity and group efficiency. Using extensive full-scale testing in various soils, the research evaluates how S/B ratios (spacing to helix diameter) influence load sharing, interaction, and failure mechanisms. Results are compared against past studies involving sands and clays, highlighting similarities and key differences. Attendees will learn how soil density and consistency influence the “critical spacing” at which anchors achieve full efficiency. Practical recommendations for field applications are presented, offering simplified spacing guidelines that can be applied even when soil information is limited. The session concludes with considerations for design reliability, right-of-way constraints, and field constructability.
Quality Control for Laterally Loaded Drilled Shafts (22 minutes)
This session provides a detailed look at quality control challenges for drilled shaft foundations subjected to lateral loading, particularly where construction visibility is restricted. Traditional inspection techniques, such as visual checks, sounding, caliper logs, PIT, and CSL, are reviewed along with their limitations in congested shafts containing anchor bolts, cages, and templates. The presentation introduces emerging technologies such as shaft profiling, base cleanliness evaluation, and thermal integrity profiling (TIP), explaining how each method enhances reliability and reduces uncertainty. Real-world cases illustrate how missed anomalies, delayed reporting, or false positives can lead to costly reconstruction or unsafe conditions. Participants will learn how incorporating improved NDT and real-time monitoring into construction workflows can enhance shaft performance assurance. Practical considerations for implementation, field planning, and data interpretation are also included.
Optimized Design of Grillage Foundations (22 minutes)
This presentation focuses on the development, installation, and full-scale load testing of steel grillage foundations used in challenging mountainous terrain. The session outlines the difficulties utilities face with access, large pad grading, equipment mobilization, and construction tolerance control when drilled shafts or other deep foundations are used. Engineers review the performance of multiple grillage configurations tested under uplift loads, with analysis of compaction methods, soil conditions, embedment ratios, and failure mechanisms. Load–deflection curves, observed ground cracking patterns, and comparisons between soil-only and soil-over-rock cases are presented. The speakers explain how test results were paired with Monte Carlo simulations to calibrate resistance factors and validate the vertical side shear design methodology. The outcome is an optimized design approach that improves reliability while reducing weight and cost for transmission structures.
Guidance on Combined Loading Cases for Transmission Line Foundations (20 minutes)
This presentation addresses the industry-wide need for consistent guidance on designing transmission foundations under combined structural and environmental loading. Current codes, NESC, ASCE 74, and GO95, provide limited direction for how to combine extreme wind, ice, flood, seismic, and scour actions with foundation resistance. The session explores environmental mechanisms such as river scour, bank loss, hydrodynamic drag, liquefaction, lateral spread, and fault-related deformation, and how these interact with typical transmission line load cases. Presenters review equations and considerations from hydraulic and geotechnical engineering practice, identifying how probabilistic and deterministic methods should be paired. Guidance is offered for selecting appropriate combined loading scenarios, such as when long-term scour should pair with storm wind cases, or when seismic effects should be considered independently. The presentation contributes to industry efforts to unify best practices and develop future standards.
Benefits and Learning Outcomes
Upon completion of this course, you will be able to:
- Describe how anchor spacing influences group efficiency and uplift capacity for helical guy anchors in different soil conditions.
- Explain modern quality control methods for evaluating drilled shaft integrity during construction.
- Discuss how full-scale testing and calibrated methodologies improve the optimized design of grillage foundations.
- Identify appropriate combined loading scenarios for transmission foundations involving structural and environmental hazards.
Assessment of Learning Outcomes
Students' achievement of the learning outcomes will be assessed via a short post-test assessment (true-false, multiple choice, and/or fill in the blank questions).
Who Should Attend?
- Utility Engineers
- Structural Engineers
- Consulting Engineers
- Contractors
- Suppliers & Manufacturers
- Researchers & Educators
How to Earn Your CEUs/PDHs and Receive Your Certificate of Completion
To receive your certificate of completion, you will need to complete a short post-test and receive a passing score of 70% or higher within 1 year of purchasing the course.
How do I convert CEUs to PDHs?
1.0 CEU = 10 PDHs [Example: 0.1 CEU = 1 PDH]