Panel zone strength in welded moment-resisting-frame connections have a significant effect on the stress and strain distribution in the connection and consequently on connection performance. It is generally believed that panel zone yielding is a yield mechanism that contributes to ductility of moment frame connections,but connections with excessive panel zone deformation may have premature connection fracture and reduced ductility. The conclusion was drawn based on the theoretic analysis and tests on T-shaped connections with continuity plates. effect of panel zone strength on ductility capacity of welded beam-to-column connections without continuity plates were investigated through three-dimensional,nonlinear,finite-element analyses of connection subassemblies. results show that strong panel zone contributes to ductile performance of connections without continuity plates.