Experimental evaluation of I-shaped beam-to-hollow circular column external diaphragm connections

With their wide range of applications in the design and construction of steel structures, rigid connections are among the most prevalent types of connections. In many cases, hollow circular columns are used as a component in moment resisting frames. Circular columns have a wide range of applications, primarily due to their high flexural strength around the principal perpendicular axes, their ductility, energy dissipation, and low susceptibility to local buckling. These hollow sections are available and used in two forms: rolled sections and sections manually manufactured using plates. The most important weak point of these sections is when they are used in moment resisting frames and structures located in areas with a high level of seismicity. In these cases, design standards necessitate the use of continuity plates along the beam’s flanges. However, due to the inaccessibility of the inner spaces of these types of columns, using continuity plates is either impossible or very difficult. This study introduces an external diaphragm connection between the I -shaped beam and hollow circular column which uses continuity plates outside the section (column). Through an experimental investigation, the behavior and strength of welded and bolted connections are evaluated under cyclic loading. The results show that the proposed detail possesses suitable strength and ductility, and provides the connection with a suitable level of rigidity. The connection satisfies the specifications of existing seismic codes.