Bolted Flange Plate Steel Moment Connections for High Seismic Region Applications

摘要

The structural steel construction industry has the desire to prequalify a bolted moment connection for use in high seismic regions. One type of such connection is the bolted flange plate moment connection in which the beam flanges are bolted to flange plates that are shop welded to the column. This combination of shop welding and field bolting is seen as an economical alternative to costly field welding of the beam flange to column flange. The AISC Connection Prequalification Review Panel is currently reviewing the bolted flange plate moment connection for inclusion in the next edition of the AISC Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications (ANSI/A1SC 358-05). A recent project at the University of California, San Diego (UCSD) investigated the cyclic behavior and design issues associated with bolted flange plate steel moment connections. The UCSD testing further expanded the experimental database in support of the prequalification of this type of connection for high seismic region applications. Three full-scale specimens consisting of W14 columns and W30 to W36 beams were subjected to an increasing amplitude cyclic loading sequence and tested to failure. All three specimens performed well and satisfied the Acceptance Criteria of the 2005 AISC Seismic Provisions for Structural Steel Buildings for special moment frame beam-to-column connections. Specimens achieved an interstory drift angle of at least 0.06 radians before failure by net section fracture. The sources of inelastic deformation included beam, column, and panel zone yielding, similar to typical welded moment connections, and additionally included deformation from bolt slippage and bearing at the bolt holes. During testing, on large drift cycles (5% and 6% drift), significant lateral-torsional buckling (LTB) of the beam and twisting of the column were observed. Twisting of columns, which has been reported in deep columns but not W14 columns, might have been mitigated had a composite slab been included.