Damage Detection Of Bridge Early-warning System And Experimental Study

Bridge early-warning system aim to send out warning in time when damage occurred to bridge structure, so that could ensure bridge safe operation. Damage detection is the core of bridge early-warning system. The efficiency and reliability of bridge early-warning system are determined by the results of damage detection.In recent years, damage detection methods based on vibration are extensively studied by scholars at home and abroad. Damage detection methods based on bridge dynamic test diagnose and evaluate damage according to the analysis of response data and dynamic parameters.The main work of this paper is as follows.First, two steps of damage detection are determined based on the analysis of characteristic and demand to damage detection method of bridge early-warning system.Second, Extreme Value Index of Wavelet Packet Energy Variation (EVI) and its critical value are proposed. The sensitivity and consistency of EVI and its critical value are analyzed though a finite element model.EVI is taken as the early-warning index in bridge early-warning system.Third, Wavelet Packet Energy Component Curvature Method, Curvature Mode Method and Flexibility Matrix Method are introduced, based on which, the method which use EVI to locate the damage is proposed. Sensitivity and Accuracy tests based on dynamic test are designed, the thought which use EVI to locate damage at first, and then use Wavelet Packet Energy Component Curvature Method to recheck according to comparison of four effects of four damage detection methods.At last, model tests of cable-stayed bridge and truss bridge are designed to simulate the effects of bridge early-warning index and damage location method which used in practical engineering. Thought set different damage situations of cable-stayed bridge and truss bridge, analyzed the effects of damage detection, basis of Practicality of bridge early-warning index and damage location method which used in practical engineering is provided.