Strain distribution and failure modes of steel lattice tower gusset plates as a function of their geometry

Steel gusset plates (SGP) are structural elements that connect and transfer loads among various members, such as beams, columns, and trusses, in steel structures like buildings, bridges, and lattice towers. Their geometry significantly affects structural performance, requiring a thorough analysis of strain distribution and failure modes to ensure the integrity and safety of structural systems. However, the design and evaluation of lattice tower gusset plates (LTGP) in particular, present challenges due to complex geometries and the lack of universally accepted design methods. This paper presents a comprehensive comparative study of the strain distribution and failure modes of LTGP across different geometries. Experimental tests were conducted using Digital Image Correlation (DIC) on specimens with different configurations, each featuring a single row of bolts. The force–displacement curves and strain distributions were analyzed to determine the influence of gusset plate width, end-distance, and the number of bolts on their behavior. The study compares the experimental data with the prescriptions of design standards. Additionally, it presents numerical modeling of LTGP connections using finite element analysis in ANSYS®, with validation against experimental results confirming model accuracy. The research program is further complemented by a parametric study examining the effects of end-distance, plate width, and bolt spacing on the ultimate strength of LTGP. • This article presents a comprehensive comparative study of strain distribution and failure modes of steel gusset plates with different geometries in lattice transmission line towers. • Evaluation of three design standards (CSA-S16, 2019; ASCE-10, 2015; Eurocode-3, 2005) reveals notable differences in their predictions, with conservative underestimation by ASCE and Eurocode, and overestimation by CSA. • The integrated approach, combining numerical modeling and experimental data through Digital Image Correlation, proves effective in enhancing understanding and establishing a robust foundation for future research and design considerations in the field. • Plate width, end-distance, and bolt spacing significantly affect steel gusset plate behavior and ultimate strength of steel gusset plates in lattice transmission line towers.