Innovative cast steel high-strength connectors for round hollow structural section brace members have been developed at the University of Toronto for use in Special and Ordinary Concentrically Braced Frames (SCBF and OCBF). The standardized connectors, now available through Cast Connex Corporation under their High-Strength Connector line of products, have been applied in the construction of various seismic-resistant steel-braced frame buildings in the United States and Canada. At one end, the connectors are designed with a circular shape and preparation to allow for complete joint penetration shop welding to a range of round tubular braces of a given outer diameter for the full development of their expected strength. At the other end, the connectors are shaped such that a bolted double-shear connection or longitudinal fillet welds can be used for connecting the shop-welded brace-connector assembly to conventional gusset plates in the field.
This paper describes the mechanical properties of the cast steel material comprising the connectors, provides an outline of the design rationale for the connectors meeting the AISC Seismic Provisions’ requirements for SCBF and OCBF brace connections, and provides a summary of the full-scale structural testing that has been conducted to validate the connector design philosophy.