Lessons Learned from Design and Test of Latticed Steel Transmission Towers

Design of latticed steel transmission towers is a challenging task which involves lengthy modeling and detailing of significant amount of steel members and connections. Testing of the towers designed validates consistency between modeling and detailing and ensures the towers are designed to withstand design loads without premature failures. This paper presents lessons learned from design and testing of latticed steel towers in a recent project of developing a family of nine (9) 500kV transmission towers. The paper provides a discussion about the process of selecting bidders for design, detailing and fabrication of latticed steel towers, and abrief discussion of determining materials used in the towers. The paper also discusses comparisons of different tower weights for various tower base widths and foundation reactions to achieve a cost effective design combining both the tower and its foundations. Examples of modeling tower members using beam elements in PLS-TOWER are presented to illustrate the importance of fully understanding the main purpose of using beam elements in TOWER. Variations between tower modeling and detailing are presented with specific attention to member and connection eccentricities. Finally, lessons learned from six (6) tower tests are discussed.