Engineering Structures, cilt.363, 2026 (SCI-Expanded, Scopus)
This paper presents the results of a comprehensive experimental study on 64 unstiffened T-stubs. All three failure modes defined in Eurocode EN 1993-1-8 were systematically examined by varying key parameters such as flange plate thickness, bolt-to-stem distance, edge distance, bolt diameter, and bolt grade. The experimental findings revealed average test-to-predicted strength ratios of 1.35 and 1.21 for Method 1 and Method 2 of EN 1993-1-8, respectively. For more than 15 specimens, however, the existing design model failed to accurately predict the failure mode. Classical double-curvature yielding was observed in the majority of specimens. However, some specimens displayed a distinct yield pattern, characterized by single-curvature yielding with corner yielding—behavior not explicitly addressed in the Eurocode. To resolve these discrepancies, the study proposes modifications to geometric parameters and introduces an additional yield pattern that incorporates the observed single-curvature yielding with corner yielding. These adjustments reduced the average test-to-predicted strength ratio to 1.06 and significantly improved the accuracy of both failure mode and yield pattern predictions. As part of the investigation, both ultimate and plastic resistances were evaluated. The average ratio of ultimate to plastic resistance was found to be 2.49, indicating a substantial reserve strength beyond the plastic limit. The proposed yield pattern was also validated through finite element analyses.