Experimental Investigation of the Performance of Gusset Plate Moment Connections under Fire Conditions

In this research, the performance of the gusset plate moment connections is experimentally evaluated in a fire condition. To achieve the research goal, 12 specimens are fabricated in a symmetric cross arrangement; accordingly, a single column along with two cantilever beams and gusset plates are considered, and the load is applied at distance from the beginning of the beam. Subsequently, the temperature of the specimens is elevated until the point of connection failure is reached. The effective parameters, including the gusset plate thickness, gusset plate steel grade, vertical load value, gusset plate length, connection type (bolted or welded), gusset plate height, and lateral restraint, are examined. Following the completion of the experiments, time-temperature and temperature-rotation curves as well as failure modes are obtained. Ultimately, the results are compared with the control specimen. The findings indicated that the lateral restraint, the gusset plate steel grade, and the applied load have significant effects on critical and failure temperatures. Lateral restraint and yield strength improvement led to 20% and 10% increase in the failure temperature, respectively. Moreover, elevating vertical load up to three times can cause a substantial 23% reduction in the failure temperature. Last but not least, fire caused a significant change in the connection’s failure modes, where parameters, including length, height, and edge angle of gusset plate, played a crucial role. Finally, by comparing the proposed gusset plate moment connection with previous inquiry prequalified moment connections, it can be concluded that not only the examined connection is cost-effective but also offers satisfactory performance at high temperatures. Noteworthy, it holds the potential for further investigation in future research and application in steel structures.