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

TL;DR

This paper explores how ambient vibration measurements and the Frequency Domain Decomposition method can be used to estimate the dynamic parameters of buildings, aiding in seismic vulnerability assessment in moderate seismic regions.

Contribution

It presents a detailed analysis of the FDD method's physical meaning and demonstrates its application to evaluate building stiffness and inter-storey drift from ambient vibrations.

Findings

Successful estimation of building modal parameters from ambient vibrations.

Validation of the method through comparison with actual earthquake recordings.

Quantitative assessment of inter-storey drift for seismic vulnerability.

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.