Mechanical and seismic behaviors of bottom-flange-bolted upper-flange-welded through-diaphragm connections

摘要

The through-diaphragm connection to a square steel tubular column is a regular connection type that is used widely in Asian countries. However, connections with traditional welded flange designs often fail through bottom flange to diaphragm weld fractures owing to the unstable quality of on-site intermittent welding. Therefore, a new type of bottom-flange-bolted upper-flange-welded through-diaphragm connection is presented to avoid premature fracture failure at the bottom flange. The construction process of the new connection is more convenient than the traditional construction. In this study, three specimens were designed and tested to investigate the mechanical properties and seismic behaviors of this new connection, and different web connecting methods were considered. The failure modes, hysteretic curves, backbone curves, and energy dissipation abilities were evaluated. Together with finite element simulations, the deforming pattern and load bearing performances were discussed in comparison with the traditional welded flange. The results indicate that the bolt and plate slip would present a slight reduction in the energy dissipation ability of the new connection. However, the strength development is similar to that of the traditional welded flange connection, and the ductility satisfied the seismic provisions in moment frame connections. A two-row regular-bolted web connection can ensure a sound load transfer at the beam web. (C) 2019 Elsevier Ltd. All rights reserved.