| Exposed column base plate connections are crucial components in earthquake-resistant steel structures, but previous research has produced a limited quantitative understanding of its load transfer mechanisms. Recently, a large-scale experimental program was performed at the University of California at Davis to achieve a fundamental understanding of the base connection response under axial compression and strong-axis bending. The study described in this Thesis complements the experimental program and consists of two series of finite element simulations conducted to: (1) develop a validated approach for simulation of exposed column base plate connections and (2) to perform an analytical parametric study using the validated approach to generalize the findings of the experimental program to untested situations. The parameters scrutinized in the numerical study are anchor rod grade and configuration, base plate size and thickness, column size, magnitude of axial load, and the direction of lateral load.;The FEM models were validated by comparing the analytical results against various experimental observations (e.g. the load deformation curve, and measurements of anchor rod strains). The finite element simulations reproduced the experimental results and produced new findings. The simulations were determined to appropriately simulate deformation (and failure) modes (i.e. deformed base plate shape, anchor rod yield, etc.), and the excellent ductility of the base connections (i.e. excess of 6% drift capacity). The "thin" base plates displayed more ductility compared to "thick" base plates. The bearing stress distribution gets concentrated underneath the column flange (e.g. compression region), and it varies depending on the base plate thickness. Contrary to current design considerations, inclined and straight yield line patterns developed on the tension and compression region of the base plate, as well as on the sides of the plate, depending on the base plate footprint and thickness. In addition, two base connections with realistic, first-story column sizes were tested to observe their response. It was discovered that a substantially "thick" base plate develops most of its yield lines on the tension region of the plate, caused by the large prying anchor rod forces. |
