Cyclic loading of end plate moment connections

Abstract

An experimental investigation of 15 cyclically loaded extended end plate connections was undertaken to assess the significance of some design parameters. The parameters investigated were beam size, bolt layout, end plate thickness, use of extension stiffeners, welding process, and weld preparation. Eleven of the 15 full-scale test specimens were designed to confine failure to the end plate and four were designed to develop the plastic moment capacity of the beam. Of the beam sizes tested (W360×51, W460×97, and W610×125) the W460×97 beam connections provided the most ductility. The relaxed bolt configuration provided more energy dissipation and connection ductility. The use of extension stiffeners improved the ability of the end plates to dissipate energy and increased the connection rotation at yield. An increase in end plate thickness results in an increase in the connection flexural strength. No significant difference in behaviour was observed between the connections fabricated using the shielded metal arc welding process and those fabricated using the flux-cored arc welding process. Bolt bending and loss of preload were observed in all the test specimens. End plate thickness prediction equations proposed by various researchers were evaluated by comparing predicted plate thickness with plate thickness used for the test specimens. New prediction equations that use yield lines in close agreement with those observed in the test specimens are proposed. The proposed prediction equations are able to predict the thickness of the end plate to within 13%. The proposed prediction equations are applicable to stiffened and unstiffened end plate moment connections with various bolt layouts. Extended end plate moment connections showed good potential for use in seismic zones.Key words: cyclic loading, energy absorption, extended end plates, moment connections, steel, yield line.