Bolted large seismic steel beam-to-column connections Part 2: numerical nonlinear analysis

A large bolted steel moment-resisting connection was studied by nonlinear numerical analysis. This connection was a single-sided beam-to-column assembly that is representative of exterior beam-to-column connections. It was composed of a W36 × 150 Grade 50 beam and a W14 × 283 Grade 50 column. The T-stubs were cut from W40 × 264 sections of Grade 50 steel. The T-stub stems were welded and prestressed by high-strength bolts to the beam flanges in a fabricating shop. Final beam-to-column assembly required no additional welding: the T-stub flanges were bolted to the column and the column shear tab was bolted to the beam web. During cyclic testing the beam deformation was minimal due to the active participation of the T-stub flanges. A separation was observed between the T-stub flanges and the column flange. The separation occurred due to plastic bending deformation in the T-stub flanges. This phenomenon allowed energy dissipation and prevented severe buckling in the beam flanges and beam web. The tests revealed the importance of the numerical analysis of the connection to obtain a better understanding of the critical performance parameters. A finite element analysis was conducted on a specimen with rectangular- shaped stems. The analysis consisted of two parts: a solid element analysis of the T-stub under tension load in the stem and a shell element modeling with buckling and instability analysis. The solid element analysis was conducted to study the local behavior of the T-stub, whereas the shell model analysis was performed to study the global behavior of the connection.