Title: Modal identification of seismically isolated bridges with piers having different heights
Authors: Georgios Kampas; Nicos Makris
Addresses: Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL 32816, USA ' Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL 32816, USA
Abstract: This paper investigates the modal identification of seismically isolated bridges when the localised nonlinear behaviour from the isolation bearing initiates at different times due to the uneven height of the bridge piers. More specifically, a three-span bridge supported on spherical sliding bearings is examined. Three different states of the same system with different natural periods emerge during an excitation; the linear system (LS), the partially isolated system (PIS) and the fully isolated system (FIS). Firstly, the paper identifies the time intervals that each state performs by using acceleration data. Subsequently, modal identification techniques such as the prediction error method and a time-frequency wavelet analysis are applied on each interval. The LS results are dependable compared to the PIS which is a mildly nonlinear system. The results corresponding to the FIS suggest that it is preferable to apply the modal identification techniques on each interval independently, rather than on the entire response signal.
Keywords: seismic isolation; modal identification; dynamic response; bilinear behaviour; time-frequency analysis; bridges; earthquake engineering; prediction error method; PEM; structural health monitoring; SHM; bridge piers; pier heights; earthquakes; spherical sliding bearings; wavelet analysis.
International Journal of Sustainable Materials and Structural Systems, 2015 Vol.2 No.1/2, pp.113 - 133
Received: 13 Feb 2015
Accepted: 07 Nov 2015
Published online: 15 Aug 2016 *