STRUCTURAL DAMAGE ALARMING OF SUSPENSION BRIDGE BASED ON SEASONAL CORRELATION OF BEAM-END DISPLACEMENTS AND TEMPERATURE

摘要

This paper focuses on applying the data of beam-end displacement measured by structural health monitoring system to construct an on-line structural damage alarm technique. The seasonal correlation analysis between displacements and temperature of Runyang Suspension Bridge is performed with regard to the 160 days health monitoring data. The correlation analysis shows that the daily averaged beam-end displacements have remarkable seasonal correlations with the temperature. The seasonal variance of the north and south beam-end displacement caused by temperature is, 37.4cm and 38.8cm, respectively. The statistical technique using 6-order polynomial is used to simulate the correlation between the natural beam-end displacements and temperature. The abnormal changes of measured displacements induced by structural damage are detected using mean value control chart. The mean value control chart exhibit good capability for detecting the damage-induced 0.8cm variances of beam-end displacements. The results reveal that the proposed method can effectively eliminate temperature influence from displacements time series and alarm the abnormal change of displacements caused by structural damage. When it is applied in structural damage alarming, if abnormal samples appear in mean value control chart, firstly, expansion joints should be detected on-site to judge whether the damage occurred to them. Furthermore, if the expansion joints are damaged they must be replaced or the alarming of structural damage state can be made out if the expansion joints are health.