Numerical simulation of improved RHS column-to-I beam flange-plate bolted connections for avoiding tensile fracture

In an attempt to find possible solution for avoiding premature occurrences of brittle fracture in rectangular hollow section (RHS) column-to-I beam connections, an improved type of connection was tested by authors. Instead of welding, the beam was connected to the flange plates by bolts, some distance away from the column face. A series of test was conducted on this improved RHS column-to-I beam flange-plate bolted connection, the results show that the improved connection does not fail by fracture as observed in the conventional connections and has a larger energy dissipation capacity. This paper describes the finite element modeling method employed to analyses both conventional welded RHS column-to-I beam and improved bolted connections. Three highly complex 3D finite element models are created, accounting for material nonlinearity, large deformation and contact behavior involved in the models. The connection models have been analyzed under some loading conditions up to failure. The comparisons with experimental data show that the finite element models have high level of accuracy and can be employed to further optimize the connection design. In addition, the ultimate moment capacity of this improved connection is found to be predicted by simple formulas based on an elementary plastic analysis, and the connection has sufficient overstrength to allow formation of plastic hinges at the beam ends