The identification of structural damage is an important objective of health monitoring for civil infrastructures. System identification and damage detection based on measured vibration data have received intensive studies recently. Frequently, damage to a structure may be reflected by a change of some system parameters, such as a degradation of the stiffness. In this paper, we propose an adaptive tracking technique, based on the extended Kalman filter approach, to identify the structural parameters and their changes when vibration data involve damage events. The proposed technique is capable of tracking the changes of system parameters from which the event and severity of structural damage may be detected on‐line. Our adaptive filtering technique is based on the current measured data to determine the parametric variation so that the residual error of the estimated parameters is contributed only by noise. This technique is applicable to linear and nonlinear structures. Simulation results for tracking the parametric changes of nonlinear elastic, hysteretic and linear benchmark structures are presented to demonstrate the application and effectiveness of the proposed technique in detecting structural damage, using measured vibration data. Copyright © 2005 John Wiley & Sons, Ltd.

In Shanghai, a number of new underground passages are being constructed, often requiring deep excavations. When the excavations are in the vicinity of existing tunnels, it is necessary to assess the influence of these excavations on existing tunnels such as displacements of the lining and additional loads on the lining. This paper presents a finite-element parametric study of tunnel behavior caused by nearby deep excavation. This study investigates the effects of several parameters that may affect the tunnel response. These parameters are: Relative position of the tunnel with respect to the excavation, tunnel diameter, excavation dimensions, and tunnel protection measures. The results reveal that the influence of the excavation on the underlying tunnel is significant in a range of ∼5 × excavation width measured along the tunnel axis; unloading further than 10 m away from the axis of the tunnel has little effect on the tunnel structure. Based on the study in this paper a better understanding of the...