Output-only identification of the modal and physical properties of structures using free vibration response

The viability of a complete structural characterization of civil structures is explored and discussed. In particular, the identification of modal (i.e. natural frequencies, damping ratios and modal shapes) and physical properties (i.e. mass and stiffness) using only the structure’s free decay response is studied. To accomplish this, modal analysis from free vibration response only (MAFVRO) and mass modification (MM) methodologies are engaged along with Wavelet based techniques for optimal signal processing and modal reconstruction. The methodologies are evaluated using simulated and experimental data. The simulated data are extracted from a simple elastic model of a 5 story shear building and from a more realistic nonlinear model of a RC frame structure. The experimental data are gathered from shake table test of a 2-story scaled shear building. Guidelines for the reconstruction procedure from the data are proposed as the quality of the identified properties is shown to be governed by adequate selection of the frequency bands and optimal modal shape reconstruction. Moreover, in cases where the structure has undergone damage, the proposed identification scheme can also be applied for preliminary assessment of structural health.

[1]  A. Grossmann,et al.  DECOMPOSITION OF HARDY FUNCTIONS INTO SQUARE INTEGRABLE WAVELETS OF CONSTANT SHAPE , 1984 .

[2]  Franklin Y. Cheng.  Matrix Analysis of Structural Dynamics: Applications and Earthquake Engineering , 2000 .

[3]  Bor-Tsuen Wang,et al.  Modal analysis by free vibration response only for discrete and continuous systems , 2011 .

[4]  A. Grossmann,et al.  DECOMPOSITION OF FUNCTIONS INTO WAVELETS OF CONSTANT SHAPE, AND RELATED TRANSFORMS , 1985 .

[6]  Shyh-Leh Chen,et al.  Wavelet analysis for identification of damping ratios and natural frequencies , 2009 .

[7]  P. Welch.  The use of fast Fourier transform for the estimation of power spectra: A method based on time averaging over short, modified periodograms , 1967 .

[8]  J. Tang,et al.  Rapid identification of structural properties based on mass response method , 2012, Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[9]  L. A. Montejo,et al.  Damping and frequency changes induced by increasing levels of inelastic seismic demand , 2014 .

[10]  M. P. Norton,et al.  Fundamentals of Noise and Vibration Analysis for Engineers , 1990 .

[11]  L. A. Montejo,et al.  WAVELET-BASED IDENTIFICATION OF SITE FREQUENCIES FROM EARTHQUAKE RECORDS , 2006 .

[12]  Yozo Fujino,et al.  Structural parameter identification by use of additional known masses and its experimental application , 2012 .

[13]  Ahsan Kareem,et al.  Wavelet Transforms for System Identification in Civil Engineering , 2003 .

[14]  Diego A. Aguirre,et al.  Wavelet-Based Damage Detection in Reinforced Concrete Structures Subjected to Seismic Excitations , 2013 .

[15]  L. G. Jaeger,et al.  Dynamics of structures , 1990 .

[16]  Curt B. Haselton,et al.  Seismic Collapse Safety of Reinforced Concrete Buildings. I: Assessment of Ductile Moment Frames , 2011 .

[17]  Hoon Sohn,et al.  Wavelet-based active sensing for delamination detection in composite structures , 2004 .

[18]  A. Miyamoto,et al.  Wavelet transform-based modal parameter identification considering uncertainty , 2006 .

[19]  Satish Nagarajaiah,et al.  Output only modal identification and structural damage detection using time frequency & wavelet techniques , 2009 .

[20]  Jinping Ou,et al.  Structural damage identification by adding virtual masses , 2013 .

[21]  Luis A. Montejo,et al.  Spectrum-Compatible Earthquake Records and Their Influence on the Seismic Response of Reinforced Concrete Structures , 2016 .

[22]  Luis A. Montejo,et al.  SYNCHROSQUEEZED WAVELET TRANSFORM FOR FREQUENCY AND DAMPING IDENTIFICATION FROM NOISY SIGNALS , 2012 .

[23]  M. Feldman.  Hilbert transform in vibration analysis , 2011 .

[24]  Patrick Paultre,et al.  Modal identification based on continuous wavelet transform and ambient excitation tests , 2012 .

[25]  Bor-Tsuen Wang,et al.  Modal analysis of mdof system by using free vibration response data only , 2008 .

[26]  Akio Nagamatsu,et al.  Method of Estimating Equivalent Mass of Multi-Degree-of-Freedom System , 1987 .