Fracture toughness demands in welded beam-column moment connections

Detailed 2D and 3D finite-element analyses are used to study fracture tough ness requirements in welded beam-column connections. Toughness demands are quantified in terms of the elastic stress intensity factor K-1 and inelasti c crack tip opening displacement. The analyses confirm observations from th e 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. Subseque nt analyses are used to examine modifications to the connection details tha t reduce loading-induced toughness demands on the welds and thereby improve the fracture resistance. Data describe how fracture demands are affected b y the weld matching ratio, joint panel shear strength, weld reinforcing, an d residual stresses.