Performance of Fire Damaged Beam-Column Joints Strengthened with Slurry Infiltrated Fiber Concrete

The reinforced concrete frame's beam-column connections are key areas for efficiently transmitting loads between the structure's linked beams and columns. A novel form of prefabricated concrete beam-column connection featuring several configurations tailored for moment-resisting frames has been created to enhance constructability. It is mentionable that the Slurry Infiltrated Fiber Concrete (SIFCON) method is being prepared for strengthening the corner beam-column Reinforced Concert (RC) joint for the first time. The main purpose of this study is to investigate the structural behaviour of beam-column joints strengthened by normal concrete NC and SIFCON in different areas of exposure and non-exposure to fire and compare it with the reference specimens under static loading. The experimental variables considered in this study include the area of concrete hybridisation (NC and SIFCON) and fire duration. The results showed that subjecting the normal concrete specimens to 30 and 45 min firing resulted in a reduction in load-carrying capacity of 6.8% and 14.5%, respectively, and with increasing burning exposure durations, the stiffness decreased dramatically. Strengthening beam-column specimens with joint SIFCON (JS), L-SECTION SIFCON (LS), and T-SECTION SIFCON (TS) resulted in an improvement in load-carrying capacity in the range between 17.7-45.8% and 14.77-50% at 30 and 45 min fire exposure, respectively, compared to the reference specimens and also resulted in an increase in the stiffness at all load levels, while strengthening the beam-column joint with TS resulted in a superior improvement in load carrying capacity by 45.8% and 50% at 30 and 45 min fire exposure, respectively, compared with the reference NC with an increase in the stiffness value. The experimental outcomes uncover a significant improvement for the strengthened specimens compared with the reference samples. Besides, the findings demonstrate that, in terms of the aforementioned indices, the strengthened specimens were recovered as comparable to the unharmed reference specimens.