Out-of-plane cyclic behavior of steel box-section twin arch ribs for bridges

With the increasing span of steel box-section arch bridges, the stability and ultimate strength of arch ribs under horizontal loading become crucial for earthquake resistance. This paper presents a numerical study on the cyclic behavior of steel box-section twin arch ribs under out-of-plane horizontal cyclic loading to assess the seismic performance of steel box-section twin arch ribs. Seventy-two finite element (FE) models of arch ribs were established and validated based on previous experimental studies. An pseudo static elasto-plastic numerical analysis was conducted to investigate the influence of the inclination angle, rise-span ratio, and width-span ratio on the cyclic behavior of the arch ribs. The results indicate that as the angle of inclination and width-span ratio increase, or as the rise-span ratio decreases, the initial stiffness and ultimate strength of the arch ribs improve. However, this also leads to an increase in internal forces within the transverse brace, resulting in local instability and damage. In addition, the inclination angle of the arch rib and the span-to-rise ratio may influence the yielding sequence of the components. Therefore, while increasing the angle of inclination of the arch rib can enhance the transverse cyclic behavior of the steel box-section twin arch ribs, it is important to consider the potential adverse effects caused by the increased internal forces on the transverse brace.