Seismic behavior of welded high-performance steel beam-to-column joints with different reinforced configurations

Extensive experimental and analytical investigations have evaluated the hysteresis behavior of welded flange-bolted web beam-to-column joints made of high-strength steels subjected to simulated earthquakes. However, the seismic behavior of newly developed high-performance seismic structural steels, which exhibit a combination of high strength and high ductility at the joint level, has been less attentively scrutinized. In this study, four welded beam-to-column joints were designed with standard or reinforced configurations. The reinforced joints included tapered haunch and transition plate connections. Hysteresis tests were conducted on these joints under low-cycle reversal loading to evaluate their seismic performance. The results indicated that the failure modes of these joints were primarily influenced by the welded heat-affected zones. Last, numerical models were developed and validated. The analysis focused on assessing their ductility coefficient, load-bearing capacity, stiffness degradation, and energy dissipation. The reinforced connections proved to be more effective in improving the initial stiffness, load-carrying capacity, and energy dissipation of the joints compared to the standard joints with the same beam and column sections. The initial stiffness of tapered haunch and transition plate reinforced joints were found to be 29.9% and 12.7% higher than that of the standard joint without reinforced configuration. And the equivalent viscous damping coefficient of the standard joint was 23% lower than the transition plate reinforced joint. However, the reinforced joints exhibited a slight reduction in ductility coefficient compared to the standard joints, with decreases of 11% and 2% for the tapered haunch and transition plate reinforced joints, respectively.