Parametric Tests on Unreinforced Steel Moment Connections

Parametric study and design of rib-reinforced steel moment connections

“…Line CJP is located at the complete joint penetration (CJP) groove weld joining the beam and column flanges because many fractures have been found at this groove weld during the Northridge earthquake. Line WAH is located at the root of the weld access hole (WAH), from which the beam flange fractured, as shown by the pre-Northridge connections [3,4,16]. Finally, line RT is located at the rib tip because stress concentration in the beam flange in this region caused fracturing of the beam flange, as demonstrated from the triangular rib-reinforced connections [4,9].…”

“…Numerous specimens have been tested to find ways of enhancing their ductility for use in future steel buildings. Several tests have displayed that connections with pre-Northridge details may fail at low plastic rotation [2][3][4]; in most cases those unreinforced connections fail to develop the plastic rotation of 3% rad required by the 1997 AISC seismic provisions [5]. The specimens typically failed owing to fracture of the beam flange and groove weld, caused by throughthickness cracking originating at the root of the weld access hole.…”

Ductile moment connections used in steel column-tree moment-resisting frames

“…The presence of the WAHs, however, creates concentrations of the stresses and highest fracture potential in the joint that has been addressed in the literature [12,13]. The localized stress concentration initiates cracking in the WAH regions and consequently leads to fracture of the beam flange, as observed in the beam-to-column connections after the earthquake [2,11] or in the laboratory [13,14]. Having the advantage of fabrication in the shop, the proposed column-tree connection was designed without WAH to prevent the possible fracturing of the beam flange caused by the WAH.…”

Optimum drilled flange moment resisting connections for seismic regions

“…Stojadinovic et al [6] conducted a series of parametric tests on pre-Northridge connections and showed that earthquake-resistant design of WUF connections should incorporate both the weld fracture and flange overstress mitigation measures, which can be achieved, for example, by changing the welding process and connection configuration. In a similar study, Ricles et al.…”