A new methodology for health monitoring of cable-stayed bridges; identifying the major features sensitive to damage/failure

Mohammad Hashemi Yekani, Omid Bahar

In this research a general methodology is presented for health monitoring of cable-stayed bridges. This methodology has two main phases: 1) identifying different damage/failure modes through linear static, nonlinear static and nonlinear dynamic time history analyses; 2) individualizing the features of the considered bridge sensitive to the recognized damage/failure modes. In order to evaluate the proposed methodology as an exemplified the Kobe earthquake is normalized into 1g in the vertical, transversal and longitudinal directions and used as the input of non-linear dynamic time history analyses of the QINGZHOU Bridge. The components are divided into a few shorter frequency ranges. The features and their values sensitive to damages/failures are recognized in each individual frequency domain. Extensive analysis using various earthquake records, the Big Bear, Chi-Chi and El-Centro earthquake records, shows that expected damages and recognized sensitive features in similar frequency domains are exactly the same as those for the Kobe earthquake. Recognized sensitive features in this study are the vertical displacement and acceleration of the main span center, lateral displacement of the top of towers, vertical displacement of some points of the main girder of deck near the towers and also strain of cables. Extensive analysis shows that by using the new proposed methodology and monitoring a few selected features of a cable-stayed bridge various source of its potential damages during strong ground motions are trustfully predicted and controlled in early steps.