Modal Parameters Identification of Damaged Buildings Based on Assumed Modes Method
A mode-parameter-identification method for damaged buildings in time domain based on assumed modes method is proposed. The problem considered is the following: assumed given is a baseline undamaged N degree of freedom linear structural dynamics model for which the system mass matrix, natural frequencies, and mode shapes are known. The objective is to determine the modal parameters of damaged one under ground motion. The several lower-order mode shapes of undamaged buildings are looked as assumed modes. The damaged system dynamics is then represented by several coupling discrete equations of motion. In these equations, generalized displacements, velocities and accelerations of the system are extracted from measured datum based on its assumed modes. Generalized mass matrix can be got from mass matrix of undamaged buildings and its mode shapes which are determined, generalized damping and stiffness matrixes are undetermined. Using least square method (LS), the generalized damp and stiffness matrixes can be got. Then the modal parameters of damaged buildings can be got solving the eigenvalue problem of the system. To alleviate the problems ill-posedness and improve its noise immunity, the truncated total least squares (TFLS) method is used. Numerical simulation shows that TTLS method has wellposedness and more noise immunity than traditional LS method. The paper conclude that modal parameters of damaged buildings can be extracted from its responses and ground motion using assumed modes method, it is useful for buildings modal identification under no stationary excitation.
Assumed modes method Modal parameter identification Ill-conditioned equation Least Square (LS) method Truncated total least squares (TTLS) method
Lijun Mao Shaolin Chen
Civil Engineering Department Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
国际会议
南京
英文
268-273
2007-10-16（万方平台首次上网日期，不代表论文的发表时间）