مهندسی عمران شریف (Aug 2018)
SUGGESTIONS TO REMOVE THE CONTINUITY PLATES OF BOX COLUMNS
Abstract
Three main parameters in steel moment-resisting connection (MRC) design are; stiffness, strength, and ductility. The response of the beam-to-column connections is strongly affected by the panel zone. Wide experimental and analytical studies have been carried out in order to examine the behavior of panel zone Northridge (1994) and Kobe (1995) earthquakes showed that excessive shear distortions could create brittle ruptures at the welds of beam-to-column connection. The results obtained from these Earthquakes have been reflected in the subsequent changes proposed to the design approach in the American and European codes. AISC prequalified connections can be used for columns if horizontal continuity plates are used inside the column. The use of internal horizontal continuity plates as thick as the beam flange plates or stiffeners has been emphasized by FEMA355-D, to provide a good seismic performance for beam-to-column connections. Continuity plates are welded to the column web and flange at the level of tension and compression beam flanges. Performing these plates in connection with I beams to wide flange columns is easy and possible. Three faces of continuity plates in moment frame connection with I section beam and Box column section can weld CJP groove weld but in the connection forth face has many difficulties. This study first discusses the effects of continuity plate in I beam to Box section moment frame connection with top and bottom plate (WFP) then recommend new details for eliminating continuity plate. Studies have shown that the elimination of continuity plate in WFP connections decreased loading capacity, rigidity and energy absorption about 43, 58 and 35 percent respectively. In addition connections are proposed in this study for WFP connection with internal continuity plates, on average leading to reduction in loading capacity, rigidity and energy absorption about 8.9, 11.6 and 9.2 percent respectively. Moreover, I shape continuity plate has better performance than other two mentioned connections.
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