SEISMIC PERFORMANCE OF SCBF BRACED FRAME GUSSET PLATE CONNECTIONS

Concentrically braced frames (CBFs) are desirable for seismic design. They are stiff and strong for preventing damage during small, frequent events, but Special CBFs (SCBFs) dissipate energy during severe, infrequent earthquakes through tensile yielding and post buckling inelastic deformation. Brace buckling places significant force and deformation demands on the brace-beam-column gusset plate connections. Variations of the AISC Uniform Force Method are used for the design of SCBF gusset plate connections, but their seismic behavior is not well understood and may not meet expectations. An analytical and experimental study into the seismic performance of CBFs and their gusset plate connections is described. The current connection design method, past research results, and results of the current research study are described. The results show improved SCBF performance may be achieved by permitting greater flexibility and inelastic deformation in the gusset plate and by designing the gusset plate welds based upon the plastic capacity of the gusset plate. This proposed design procedure balances the resistances predicted for the various yield mechanisms and failure modes of the brace and the connection