Passive Hybrid System for Seismic Failure Mode Improvement of a Long-Span Cable-Stayed Bridges in the Transverse Direction

Abstract

This paper presents a numerical study on the seismic damages and failure modes of a trial designed cable-stayed bridge (CSB) with a central span of 1,400 m under earthquake excitations. A passive hybrid control system is proposed to mitigate the seismic damage and improve the failure mode of the CSB; this is composed of a passive control system and several supplemental nonstructural links used as sacrificial energy dissipation devices. The passive control system, including conventional viscous fluid dampers (VFDs), is presented for comparison with the hybrid system. The results show that the top and bottom regions of the tower are simultaneously subjected to severe damage under extreme ground motion, indicating that the tower experiences an unexpected failure mode with double plastic hinges, whereas the piers experience a typical flexural failure mode, with only one plastic hinge concentrated at the bottom region of the pier in the transverse direction. The effects of the proposed passive hybrid control system on seismic damage control are superior to those of the passive control system with VFDs. As a result, the passive hybrid control strategy can successfully control seismic damage and effectively improve the failure mode of the CSB so that its seismic performance meets damage control targets based on seismic damage criteria.