Seismic performance of cable-stayed bridges under large earthquake ground motions considering the loss of stay cables

Abstract

Stay cables in cable-stayed bridges are essential components to transmit deck loadings. However, cable loss events have been occasionally observed both in service life and under extreme situations like earthquakes. This study systematically investigates the seismic performance of a case cable-stayed bridge considering the loss of one cable or multiple cables during earthquake excitations. It is revealed that the cable loss would lead to the larger seismic demands of the cable-stayed bridge whereas the detrimental effect due to cable loss is highly sensitive to the cable loss location and loss stress. In general, the loss of the longer cable would be more harmful to the bridge system due to the back-stay effect. Meanwhile, the largest seismic response is reached when the maximum cable-loss-induced responses and the maximum earthquake-induced responses occur at the same time. The loss of one cable causes a large increase in force variation of the adjacent cables, which might lead to progressive cable loss. The ultimate states of the bridge are defined concerning the ultimate longitudinal displacement at the deck end, the ultimate deck bending moment, and the ultimate tower bending moment. The case cable-stayed bridge can sustain at maximum the loss of four cables; otherwise the ultimate state of the longitudinal displacement at deck end is exceeded. Due to the significant interactions between the oscillations induced by the earthquake and by the cable loss, the linear superposition method does not apply to the seismic response of the bridge including the cable loss effect.

Keywords

• Cable-stayed bridge
• Cable loss
• Earthquake effect
• Ultimate state
• Sensitivity analysis