procedures, both normal and shear force components are anticipated on each gusset interface to obtain compact and economical gusset connections. However, only brace action force was considered in these procedures, and influence of surrounding framing members on the gusset connection performance was simply ignored.As shown in Figure 2, the beam-column joint would either open or close under horizontal seismic action that introduces additional frame action force on the gusset plate (see F g in Figure 2). Apparently, the frame action effects would become increasingly significant when the framing members deformed with a large drift under severe earthquakes. This issue has always been a common concern for concentrically braced frames, especially for the framing systems installed with brace-type hysteretic dampers (e.g., BRBs). Nonlinear time-history analysis by Chen et al. [20] showed that the inter-story drift ratios on the BRBFs could be ranging from 3% to 4% radians under severe earthquakes. This again raises more concerns for safety of these gusset connections if a large drift ratio occurs. Recent tests on large-scale BRBFs with steel framing showed that the frame action would cause fracture near the gusset tips ( Figure 3a), [21][22][23] shear rupture on the gusset-to-beam interface (Figure 3b), [24] or even complete rupture on both gusset interfaces (Figure 3c), [25] prior to failure of the BRBs. To estimate the frame action force, an equivalent strut located at points of 0.6 times the gusset length and height from the column and beam flanges, respectively, was proposed recently to represent the gusset plate. [23,[26][27][28] The strut force was derived by deformation compatibility between the strut and the beam flange. By assuming appropriate stress distribution, several practical procedures, [23,[26][27][28] by combining the brace action and frame action forces into design check of the gusset interface strength, have been presented. FIGURE 2 Frame action effects on welded corner gusset connections FIGURE 1 Corner gusset connections in concentrically braced frames FIGURE 3 Typical failure modes of welded corner gusset connection 2 of 27 ZHAO ET AL. AUTHOR BIOGRAPHIES Junxian Zhao, PhD, is an associate professor of School of Civil Engineering and Transportation, South China University of Technology. His research is on seismic design of structures, innovative seismic damping structural systems, and resilient structures.Ruobing Chen, BS, is a graduate student of School of Civil Engineering and Transportation, South China University of Technology. His research is on the seismic performance of steel buckling-restrained braced frame. 26 of 27 ZHAO ET AL. Yun Zhou, PhD, is a Professor of the School of Civil Engineering, Guangzhou University. His research is on development and implementation of the new structural system with dissipated devices. Haichao Yu, BS, is a graduate student of School of Civil Engineering and Transportation, South China University of Technology. His research is on the seismic performance of reinf...