Condition assessment of structures under unknown support excitation

A new method is proposed to assess the condition of structures under unknown support excitation by simultaneously detecting local damage and identifying the support excitation from several structural dynamic responses. The support excitation acting on a structure is modeled by orthogonal polynomial approximations, and the sensitivities of structural dynamic response with respect to its physical parameters and orthogonal coefficients are derived. The identification equation is based on Taylor’s first order approximation, and is solved with the damped least-squares method in an iterative procedure. A fifteen-story shear building model and a five-story three-dimensional steel frame structure are studied to validate the proposed method. Numerical simulations with noisy measured accelerations show that the proposed method can accurately detect local damage and identify unknown support excitation from only several responses of the structure. This method provides a new approach for detecting structural damage and updating models with unknown input and incomplete measured output information.

[1]  Duan Wang,et al.  System Identification with Limited Observations and without Input , 1997 .

[2]  Li Jie,et al.  A statistical average algorithm for the dynamic compound inverse problem , 2003 .

[3]  Jian Chen,et al.  Hybrid identification method for multi-story buildings with unknown ground motion: theory , 2006 .

[4]  J. Chen,et al.  Simultaneous identification of structural parameters and input time history from output-only measurements , 2004 .

[5]  Q. W. Yang,et al.  A coupled method for structural damage identification , 2006 .

[6]  Per Christian Hansen,et al.  Analysis of Discrete Ill-Posed Problems by Means of the L-Curve , 1992, SIAM Rev..

[7]  Palle Andersen,et al.  Modal Identification from Ambient Responses using Frequency Domain Decomposition , 2000 .

[8]  Achintya Haldar,et al.  Element-level system identification with unknown input , 1994 .

[9]  Siu-Seong Law,et al.  Damage detection in simply supported concrete bridge structure under moving vehicular loads , 2007 .

[10]  Charles R. Farrar,et al.  Comparative study of damage identification algorithms applied to a bridge: II. Numerical study , 1998 .

[11]  Charles R. Farrar,et al.  A summary review of vibration-based damage identification methods , 1998 .

[12]  S. R. Ibrahim Efficient random decrement computation for identification of ambient responses , 2001 .

[13]  Achintya Haldar,et al.  Element Level System Identification with Unknown Input with Rayleigh Damping , 2004 .

[14]  S. S. Law,et al.  Identification of system parameters and input force from output only , 2007 .

[15]  Xinqun Zhu,et al.  Time-varying wind load identification from structural responses , 2005 .

[16]  Nathan M. Newmark,et al.  A Method of Computation for Structural Dynamics , 1959 .