Damage Mechanism and Load-Carrying Capacity at Girder End of Existing Steel Girder Bridge Under Seismic Lateral Force

Existing steel girder bridges have often suffered damage at the girder ends during large-scale earthquakes. Against such damage cases, experimental and analytical studies on the failure behavior of steel girder end under lateral force have been carried out so far. However, there are still few study cases focusing on the three-dimensional behavior and load-carrying capacity of the whole superstructure system. In this paper, pushover analyses with nonlinear finite element models were performed for a composite steel I-girder bridge in order to investigate the damage mechanism and load-carrying capacity at the girder end under seismic lateral force in the longitudinal and transverse direction. In addition, parametric studies on the effect of additional reinforcing ribs at the pin support area on the load-carrying capacity was conducted. Pushover analyses clarified the damage behavior at the girder ends, including the plasticization and deformation process of each steel component, and also revealed that the load-carrying capacity in the transverse direction is smaller than that in the longitudinal direction. It was found that reinforcing ribs provide a resistance function against lateral forces not only in the longitudinal direction but also in the transverse direction and improve the load-carrying capacity.