Designing Steel Connections in Substation and Transmission Structures
Sandman Structural Engineering’s Electrical Power team routinely works at the edges of prescriptive steel design. Substation and transmission structures are defined by irregular load paths, multi-axial forces, and connection geometries that rarely align with textbook AISC examples. As the team’s portfolio expanded, so did the frequency of atypical steel connections that demanded a more rigorous and transparent verification approach.
Engineering Challenges
To address this challenge, the team adopted IDEA StatiCa as a core tool for analyzing and verifying complex connections across multiple power infrastructure projects, including substations, transmission structures, and associated steel support frames. Power structures don’t consistently give you clean, repeatable shear tabs and moment connections. Every structure has its own load path and ideally would have a tool that can actually show how the forces flow through the steel.
About the Structures
As you can see in their featured projects, Sandman Structural Engineering's work has encompassed a range of electrical infrastructure structures subjected to significant axial forces, bending moments, and load reversals driven by conductor tension, equipment loads, wind, and ice. Steel A-frames, braced frames, and portal configurations were common, with connections often acting as critical articulation points in the global load path. Rather than isolating a single project, Sandman’s Electrical Power Team engineers applied IDEA StatiCa across a series of designs, using it to develop consistent, defensible connection solutions for both highly complex and relatively simple details within the same structures.
A-Frames and H-frames are one of the most common dead-end structures in a substation facility. Dead-end structures are where the electrical line ends or angles off and are usually made with heavier steel because they carry the transmission line conductors at full tension or at slack span.
Picture from: https://www.sandmanse.com/projects/king-ranch-substation
The A-frames have at least four legs and one conductor beam. The "knuckle" connection joins two legs to the conductor beam and the mast at the top. The joint was required to accommodate large axial forces while allowing rotation and redistributing bending effects without introducing unintended secondary stresses. Traditional AISC design approaches offered limited guidance for this configuration, and simplified hand calculations risked excessive conservatism or incomplete force representation. Spreadsheet-based methods would also be limited in capturing the true interaction between plates, bolts, and welds under combined loading.
Connection Solutions
IDEA StatiCa Connection allowed the team to model the knuckle joint in full three-dimensional detail, capturing plate contact, bolt behavior, weld forces, and nonlinear stress distribution using the CBFEM approach. This enabled direct verification of the connection under the governing load combinations without relying on conservative assumptions about force distribution. Engineers were able to evaluate stress flow through the knuckle plates and connecting members, confirm rotation capacity, and optimize the geometry to achieve a balanced, efficient design.
Beyond the knuckle connection, the same structure included several simpler connections, such as HSS Column splices and insulator beam-to-column leg connections. These were also verified in IDEA StatiCa, allowing the team to apply a consistent workflow across the entire connection package. Even for details that could have been checked using traditional methods, the software provided clarity and confidence by visualizing stresses and utilization levels, reducing the likelihood of overlooked governing limit states.
Solution and Results
By integrating IDEA StatiCa into their electrical power workflow, Sandman Structural Engineering significantly reduced design uncertainty and internal review time. Engineers could quickly iterate connection geometry, immediately see the impact on stress distribution, and converge on solutions that were both constructible and efficient. The ability to produce clear, code-based calculation packages, including reports, detail drawings, and 3D models, also improved communication with reviewers and project stakeholders, particularly on connections that fell outside standard detailing conventions.
Rather than avoiding unconventional details or defaulting to overly conservative designs, engineers were able to engage with complex connection behavior at an earlier stage in the design process. This resulted in cleaner load paths, better-aligned member forces, and increased confidence that the final structures would perform as intended under real operating conditions.
Summary
IDEA StatiCa is proud to have been a part of Sandman Structural Engineering’s Electrical Power toolkit. Its application across multiple substation and transmission structure projects has demonstrated that even in industries dominated by unique, one-off connections, rigorous nonlinear connection analysis can be both practical and repeatable. By embracing tools capable of matching the complexity of power infrastructure, the team continues to deliver reliable, well-verified designs while expanding what is feasible within steel connection engineering.
United States
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