Experimental investigation of rectangle – I profile joints on weak axis subjected to fire under cyclic loads

Steel structures are crucial research subjects due to their performance under fire and cyclic loading conditions. Ongoing studies aim to enhance our understanding of these areas. Fire can severely damage steel structures, while cyclic loading assesses their durability and flexibility. This study investigates 7 column-beam connection specimens with varying connection types under both fire and cyclic loading conditions. The ISO-834 fire curve was used to simulate fire effects, and the FEMA-350 loading protocol was applied to replicate cyclic loading scenarios. The research considered variables such as the distance of the beam connection points from the column-beam junction and the type of connection. Key parameters including load-carrying capacity, maximum displacement, ductility, rigidity, maximum rotation angle, and energy absorption capacity were measured and analyzed. The findings indicate that increasing the distance of the connection area from the column-beam connection enhances load-carrying capacity. In samples where connections were made on the weak axis, column buckling was observed, whereas buckling was not seen in the beams. The failure modes recorded in these experiments were compared to existing literature, which primarily focused on specimens with strong axis connections. This research provides valuable insights into the behavior of different connection designs under fire and cyclic loading conditions.