| The beam-column moment connections, which were considered having good performance for seismic resistance in steel moment resisting frames, have beendesigned following a codified design procedure. The unexpected numerous brittle connection failures discovered after the 1994 Northridge earthquake invalidated thethen existing design for connections. The observed damages have been widely investigated both analytically and experimentally; there is consensus that numerous factors must have contributed to the brittle connection fractures including local details and parameters.In this paper, the effect of the local geometric details on the behavior of welded-bolted connections is studied through 3D nonlinear finite-element analyses of connection subassemblies. The local geometric details considered include longitudinal length and height of access hole in beam web; material nonlinearity and geometricnonlinearity are included in nonlinear analyses. The finite-element model utilized inthis study is composed of 3D four-node shell; both monotonic loading and cyclic loading are used for analyses. The analytical results provided information on basic performance and the effects of configurations of access hole on the behavior of steel moment connections under seismic loading. The analytical results shows that enlarging the longitudinal size of access hole effectively minimizes the potential of fracture at the groove welds between column and beam flange and the root of access hole. But over increasing the length of the access hole will give rise to the loss of lateral stability of beam. Reducing the height of the access hole only does benefit to the standard connection in common use whose length of the access hole is shorter; thepotential for facture at the root of the access hole is minimized. Based on theanalytical results, recommendations for the seismic design of beam-column moment connections are given. |
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