Seismic Performance of Beam-Column Connection According to Load Velocity

Brittle fracture greatly influences the deterioration of the plastic deformation ability of steel structures. One of the main causes of brittle fracture is high load velocity. Currently, most of the seismic performance evaluation of connections is conducted through static experiments specified in the standard. This experimental method involves applying a constant repetitive load at a low velocity of about 0.5-1.0 mm/s. It exhibits different properties from dynamic loads with high load velocity and irregularities that occur during an earthquake. Accordingly, there is a possibility that the existing seismic performance evaluation did not sufficiently consider brittle fracture according to factors such as decrease in maximum strain due to a high load velocity. Based on this, this study conducted static and dynamic experiments on beam-column connections to investigate the effect of load velocity on seismic performance. Additionally, this study evaluated the effect of load velocity on seismic performance, including hysteresis characteristics, plastic deformation ability, and input energy. The general results of the dynamic experiment showed a decrease in the initial stiffness and maximum strength of the connection compared to the static experiment. But higher yield strength and yield strain angle were observed. A specimen exhibited different failure modes between static and dynamic experiments. Overall, the study highlights the importance of considering the effect of load velocity on the seismic performance of structural materials and suggests that evaluating the seismic performance of structures under dynamic loading conditions, considering the load velocity, can enhance the safety of structures in earthquake-prone areas.