Effect of Local Details on Ductility of Welded Moment Connections

The results of a 3D finite-element study of the inelastic behavior of unreinforced, flange-welded moment connections in steel seismic moment resisting frames is presented. Computer models of connection subassemblies with notch tough weld metal were developed using the general-purpose computer program ABAQUS. Several issues were addressed in the study: (1) geometry and size of the weld access hole; (2) control of inelastic panel zone deformation; and (3) benefit of a welded beam web. The analytical results provided information on basic performance and the effects of these parameters on inelastic performance, thereby furthering the current understanding of welded connection behavior under seismic loading. Based on the results, recommendations for the seismic design of connections are given. The recommendations include using a groove welded beam web attachment with supplemental fillet welds along the edges of the shear tab and a modified weld access hole geometry. The results indicate that a strong panel zone enhances inelastic connection performance, suggesting that they be used in design. The incorporation of the recommendations into a test program showed good connection ductility in the test specimens.