Earthquake Engineering Research - HKU Libraries - The University ...

Proceedings of the International Conference on
Advances and New Challenges in Earthquake
Engineering Research, Hong Kong Volume
ACTIVE CONTROL STUDY OF CABLE-STAYED TING KAU
BRIDGE UNDER STOCHASTIC EARTHQUAKE EXCITATION
Y. Q. Ni 1 , J. M. Ko 1 , Z. L. Huang 2 , J. Y. Wang 1
1 Department of Civil and Structural Engineering, The Hong Kong Polytechnic University,
Hung Horn, Kowloon, Hong Kong
2 Department of Mechanics, Zhejiang University, Hangzhou 310027, P. R. China
ABSTRACT
Structural control provides an efficient means for protection of cable-stayed bridges against
earthquakes, wind and other hazards. Although the concept of active control of cable-stayed bridges
has been proposed at the end of the seventies, studies on active seismic response control of cablesupported
bridges referring to detailed bridge models have evolved only in recent years. In this paper,
a stochastic optimal control strategy is developed for seismic response mitigation of cable-stayed
bridges with use of active mass drivers (AMDs). The cable-stayed Ting Kau Bridge in Hong Kong is
selected as a paradigm to demonstrate the seismic control efficacy of the proposed strategy. Simulation
studies show that seismic response of the bridge can be significantly reduced by implementation of
AMDs, and the control design can be performed with use of only a few dominant modes. It is found
that installation of AMDs on top of the bridge towers and at the middle of the main spans can achieve
good control effectiveness. The control effectiveness for the deck displacements and internal forces
under transverse seismic excitation is better than that under longitudinal seismic excitation.
INTRODUCTION
Due to high flexibility and low damping, a long-span cable-stayed bridge is vulnerable to dynamic
loading such as earthquakes and typhoons. Structural control provides an efficient means for protection
of cable-stayed bridges against earthquakes, wind and other hazards. Although the concept of active
control of cable-stayed bridges has been proposed as early as the end of the seventies (Yang &
Giannopolous 1979a,b), substantial research on this subject did not progress in the eighties. Studies of
applying active control to cable-supported bridges have revived in the last decade. While active control
of wind-induced flutter vibration has been extensively studied using both mechanical and aerodynamic
measures, active seismic control of cable-supported bridges has essentially focused on exploring active
cable tendon control and decentralized control techniques by referring to simple structural models.
Studies on active seismic response control of cable-supported bridges referring to detailed bridge
models have evolved only in recent years (Miyata et al 1996; Shoureshi & Bell 1996; Paulet-
Crainiceanu 1998; Schemmann & Smith 1998a,b). A benchmark problem for seismic response control
of the cable-stayed Cape Girardeau Bridge has been recently developed (Dyke et al 2000). A state-ofart
review of active/semiactive control for cable-supported bridges is available (Ni et al 2001a).