Dynamic parameters of structures extracted from ambient vibration measurements: An aid for the seismic vulnerability assessment of existing buildings in moderate seismic hazard regions

Abstract

During the past two decades, the use of ambient vibrations for modal analysis of structures has increased as compared to the traditional techniques (forced vibrations). The Frequency Domain Decomposition method is nowadays widely used in modal analysis because of its accuracy and simplicity. In this paper, we first present the physical meaning of the FDD method to estimate the modal parameters. We discuss then the process used for the evaluation of the building stiffness deduced from the modal shapes. The models considered here are 1D lumped-mass beams and especially the shear beam. The analytical solution of the equations of motion makes it possible to simulate the motion due to a weak to moderate earthquake and then the inter-storey drift knowing only the modal parameters (modal model). This process is finally applied to a 9-storey reinforced concrete (RC) dwelling in Grenoble (France). We successfully compared the building motion for an artificial ground motion deduced from the model estimated using ambient vibrations and recorded in the building. The stiffness of each storey and the inter-storey drift were also calculated.

Hybrid probabilities and error-domain structural identification using ambient vibration monitoring

“…Errors in measurements include the digitization errors (time stamping) that are negligible, the assumption of white noise input and the precision of the modal analysis method used. The assumption of white noise input is robust as shown by Michel et al [28], with variations lower than 1% even for a short energetic signal. Errors due to the technique used include the precision of the spectral estimation and the mode selection errors that are already included in the variability found across the datasets.…”

“…Assumptions underlying this method, are: a white noise input, a low damping ratio and orthogonal close modes. The method has been shown to be robust to the first assumption [28,29] and the second assumption is generally fulfilled in civil engineering structures. The third assumption, however, is important when dealing with torsion modes.…”

Quantifying the Effects of Modeling Simplifications for Structural Identification of Bridges

“…The technique used here is the Frequency Domain Decomposition (FDD) method (Brincker et al 2001). This technique was already successfully used for civil structures (Michel et al 2008;Goulet, J.-A., Texier, M., Michel, C., Smith, I., and Chouinard, L. (2014). Quantifying the effect of modelling simplifications for structural identification of bridges.…”

Seismic response of an 8-story RC-building from ambient vibration analysis

“…Operational Modal Analysis (OMA) is generally preferred to forced vibration measurements due to the fact that the same modal parameters can be obtained from vibration data in operational rather than laboratory conditions (Reynders, 2012). There are several studies that have used ambient vibration testing for the identification of the dynamic behavior of civil engineering structures (Brownjohn, 2003;Ventura et al, 2003), finite element calibration and updating (Teughels, 2003;Jaishi and Ren, 2005), vulnerability assessment (Guéguen et al, 2007;Michel et al, 2008;Michel et al, 2012) and damage detection (Peeters, 2000).…”