Finite element modeling of gusset plate failure using OpenSees

Graduation date: 2015The collapse of the I-35W Bridge in Minneapolis, MN in 2007 prompted an investigation into the design and inspection of the steel truss bridges. Further investigation into the collapse revealed that a gusset plate experienced sway buckling, causing the bridge failure. This bridge failure motivated research into the analysis and design of gusset plates. Another major motivation for the current research is the effect of the connecting member's stiffness on the capacity of the gusset plate, which is not considered in the current design methods. The research presented in this thesis discusses a nonlinear finite-element analysis approach using OpenSees for load rating gusset plates in steel structures.\ud Using OpenSees to analyze and design gusset plates is a new approach and therefore validation of the model was required. Simple tension, bending, shear, h-refinement, element type, patch, and elastic range tests were conducted to validate the model. The major parameters studied in this research include: element size, material properties, connecting member stiffness, plate geometry, out-of-plane shape, and magnitude of out-of-plane imperfection at the loaded members in the gusset plate. The displacement at the centroid of the loaded members was monitored as well as out-of-plane displacement and stress contours in the gusset plate.\ud The results showed a strong correlation to other finite-element analysis program predictions and experimental results from sway buckling experiments. This research affirmed recent findings that the connecting member stiffness has a significant effect on the load capacity of a gusset plate connection. The results and comparisons also show that the new method using OpenSees is conservative in predicting sway buckling in gusset plates with connecting members. The predicted failure load for both single and double gusset plate connections was found to be conservative as well. The current research has shown great promise in its ability to accurately and conservatively predict failure of gusset plates, which will assist in the design of gusset plates in the future