Date of Award
8-22-2025
Date Published
September 2025
Degree Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Civil and Environmental Engineering
Advisor(s)
Eric Lui
Keywords
Finite element analysis;Gusset connections;Inelastic buckling;Partial plane shear yielding (PPSY);Truss analogy
Subject Categories
Civil and Environmental Engineering | Civil Engineering | Engineering
Abstract
Gusset plates are critical components in steel structures, serving as primary connection elements for structural members in buildings and truss bridges. The failure of gusset plates—particularly due to buckling—can lead to sudden and catastrophic structural consequences. Despite their significance, current design codes offer rather limited guidance on how to predict buckling capacity accurately, and often ignore key parameters that have large impact on the capacity of gusset plates. To address this gap, this dissertation proposes the use of truss analogy, viz., a Strut-and-Tie Model (STM)-based analytical framework, to predict the yielding, fracture and buckling capacities in gusset plates. The primary aim is to propose a more rational model that not only captures the mode of failure but also reliably assesses the behavior of gusset plates, in contrast to conventional empirical assumptions. To account for yielding and fracture in gusset plates, this study proposes modifications and extensions to the current design approach, which is presently limited to the Whitmore region of the plate, to include other critical regions. While built upon the current approach, the proposed methodology is applicable to other regions of the gusset plate, thereby expanding its pertinence and predictability. For gusset plate failure due to buckling, which is considered more challenging, this study validated a simplified finite element (FE) modeling approach through comparison with eleven test results from two well-known experimental programs. The results demonstrated that, despite geometric simplifications, the FE models accurately captured both the ultimate capacity and the deformation behavior of these gusset plates, confirming their reliability for subsequent parametric studies. In carrying out the buckling analysis, 96 simulation cases were used. The study began by systematically eliminating secondary variables such as bolt spacing, cut length and bracing stiffness, which were found to have negligible impact on the global capacity and shear stress distribution. This filtering process ensures that the model calibration focuses only on the most influential parameters. In addition, a convergence study was conducted using 15 representative models to determine an appropriate mesh size, which was set to 1% of the gusset plate's edge length, ensuring a balance between computational efficiency and solution accuracy. Subsequently,130 finite element models for corner gusset plates and 216 models for truss gusset plates were developed to investigate the effects of key analytical parameters. Among these, factors such as gusset plate thickness, inclination angle of the bracing/diagonal member, connected length and width, applied load ratios, and the length of the Whitmore region were identified as having significant influences on structural response and were therefore incorporated into the analytical model. Based on the compressive principal stress vectors obtained from the finite element results, the gusset plate was idealized as three distinct components. Taking into account the nonlinear material behavior, a stress evaluation method was formulated to capture the non-uniform stress distribution within the gusset plate. Given that buckling failure often occurs on the edge of a gusset plate, the stress distributions along the gusset plate’s vertical and horizontal free edges were used to perform curve fitting based on plate buckling theory. The analytical predictions were shown to give good agreement with the finite element results across a broad range of geometric configurations and loading conditions, demonstrating the robustness and predictive accuracy of the proposed model. Moreover, an additional 86 finite element models were developed to investigate the relationship between the key parameters identified above and the occurrence of Partial Plane Shear Yielding (PPSY). Based on the finite element analysis (FEA) results, the potential critical surfaces where PPSY might initiate were identified. By combining these findings with the stress evaluation method proposed earlier, a predictive approach for PPSY was developed. Finally, based on the analytical models developed above, a comprehensive design guideline was proposed. For gusset plates under tension, both the effects of yielding and fracture are explicitly considered; and for gusset plates under compression, this guideline incorporates three design approaches—elastic buckling, inelastic buckling, and Partial Plane Shear Yielding (PPSY). By enveloping the critical conditions from each approach, the required gusset plate thickness can be determined directly from the geometric configuration of the connection.
Access
Open Access
Recommended Citation
Zheng, Dong, "A Rational Approach to Analyze and Design Gusset Plates Using Truss Analogy" (2025). Dissertations - ALL. 2207.
https://surface.syr.edu/etd/2207
