It is often necessary to reinforce connections where there must be moment resistance. This is often the case where lateral loads are high, such as in the case of wind or seismic loading. Wind loading is a significant issue in tall buildings as these essentially act as cantilever structures where the structure of the building must resist high bending moments at the base, but at the top the connections will need to resist shear.
This is a flange-plated moment connection to the column. As such, it is transferring shear through the 5 bolt shear tab and the flange plates are transferring the design moment. The flange plates are the principal connection here rather than reinforcement for the apparently lightly loaded shear tab. This is a cruciform column, with the plates in the column being continuity plates (transverse stiffener plates) that provide continuity for the moment transfer across the column.
They have to align with the beam flanges as closely as possible to maintain the load path and prevent failing the column flanges in bending.
|More to come on some amazing seismic bracing from New Zealand!|