Performance of Arched Steel Haunches Equipped with Rib Element under Cyclic Loading

This paper introduces a novel technique called arched steel haunches with rib element (ASHR) for seismic retrofitting of RC frames. In this approach, the arched haunch is equipped with a steel ring or link, as the rib element (RE). A simplified physical model was proposed to approximate their behavioral curves. To evaluate the model’s accuracy, a series of cyclic load tests on arched steel haunches, with and without RE, were conducted. The experimental responses showed that by increasing the RE stiffness, the maximum damping ratio decreased conversely, while the strength, plastic stiffness, and even dissipated energy increased. Accordingly, the tensile and compressive strength increased up to 1.5 and 1.35 times, respectively. However, the elastic stiffness did not vary compared to the reference specimens; the tensile plastic stiffness increased up to three times and, the ultimate secant stiffness in tension and compression enhanced up to 1.56 and 3.9 times, respectively. Moreover, the total energy dissipation upgraded up to 1.39 times with the fusing of the rib elements. It should be noted that the results of this pilot study will be used in future research on the experimental behavior of the reinforced concrete beam-column joints.