Detection and Localization of Degraded Truss Members in a Steel Arch Bridge Based on Correlation between Strain and Temperature

Abstract

Taking advantage of the structural health monitoring system installed on the steel truss arch girder of the Dashengguan Yangtze Bridge, the monitoring correlation between strain and uniform temperature at night is obtained, and then the correlation analysis of wavelet packet decomposition is carried out, which can effectively decrease the discreteness of the monitoring correlation. After that, the whole finite-element model of the Dashengguan Yangtze Bridge is simplified into one top chord member, one diagonal web member, and one bottom chord member with imposed displacement movements on the supports. The simulated correlation between static strain and temperature is calculated using the flexibility equation of force method from the simplified finite-element model, which is close to the monitoring correlation, and the first-order derivative of flexibility equation is used to remove the influence of temperature action. Furthermore, the influence of degrading axial flexibility is analyzed, showing that the linear slopes kA∼kH are primarily affected by the degradation of chord members {TCa,−2,TCa,−1,TCa,0,TCa,1,TCa,2,TCa,3}, {TCb,−2,TCb,−1,TCb,0,TCb,1,TCb,2,TCb,3}, {BCa,−2,BCa,−1,BCa,0,BCa,1,BCa,2,BCa,3}, and {CVa,1}, and using the monitoring data, the method of detecting and locating the aging truss members is finally put forward.