Fracture toughness demands in welded beam-column moment connections

Detailed 2D and 3D finite-element analyses are used to study fracture toughness requirements in welded beam-column connections. Toughness demands are quantified in terms of the elastic stress intensity factor K-1 and inelastic crack tip opening displacement. The analyses confirm observations from the Northridge earthquake and full-scale connection tests that standard, pre-Northridge connections with built-in weld root flaws and low toughness E70T-4 weld metal are likely to fracture without significant yielding. Subsequent analyses are used to examine modifications to the connection details that reduce loading-induced toughness demands on the welds and thereby improve the fracture resistance. Data describe how fracture demands are affected by the weld matching ratio, joint panel shear strength, weld reinforcing, and residual stresses.