System Identification of Instrumented Bridge Using Earthquake-induced Record

A number of seismic response records obtained from instrumented bridge during earthquake provide opportunity to assess structural performance and integrity by evaluating structural dynamic characteristics and its possible changes due to earthquake. In this paper a methodology to identify dynamic characteristics of instrumented bridge based on earthquake-induced vibration is presented. A time domain approach based on input-output mapping OKID-ERA algorithm is applied here and its performance is studied in simulation case to examine the stability of modal parameters. The applicability of OKID-ERA algorithm is verified with earthquake record from Matsunohama Bridge. NOMENCLATURE ( ) z k input vector of ground motion ( ) x k state vector ( ) y k output vector of structure response ( ) v k input vector in observer equation q ,n, m number of input, state, output channel [ ],[ ],[ ],[ ] A B R D system state space matrix [ ],[ ] A B observer state space matrix [ ] V input-output matrix [ ] k Y system Markov parameter [ ] k Y observer Markov parameter [ ( 1)] H k − Hankel matrix ψ , λ poles [ ],[ ] Φ Ω mode shape , modal participation matrix ω ,ζ natural frequency, damping ratio