Research On Deterioration Identification Method Of Cable Supported Bridge Structure Based On Mobile Monitoring

The mobile vibration monitoring method has the advantages of high utilization rate of acquisition equipment and complete spatial location information,so that it has a broad application prospect in vibration monitoring and deterioration identification of bridge structures.This paper proposes a small mobile monitoring platform consisting of a power car and a small rigid trailer,which is applied to the automatic continuous modal parameter acquisition for cable supported bridge structures.A probabilistic residual fusion index is proposed to identify local structural deterioration based on the high resolution mode shape obtained by mobile monitoring.The following research work is mainly carried out:Acquisition performance analysis and construction design of mobile platform.The platform is decomposed into a power car and a small trailer,and the dynamic characteristics of the small trailer are analyzed.At the same time,the connection between the trailer and the power car is designed to isolate the vibration of the power car.The acquisition performance of the platform is tested,the vibration signal obtained by the vibration pickup mounted on the platform is as same as it is placed directly on the surface of the structure.Fast continuous mode identification of cable supported bridge structures on site.Automatic continuous acquisition and fast modal recognition algorithms are configured for mobile platforms.Just one fixed reference point combined with one or two mobile platforms is needed to realize efficient and continuous identification of bridge deck modal parameters.The platform has been applied to the field modal tests of a tied-arch bridge and a cable-stayed bridge,and the good modal identification results have been obtained.Identification of deterioration of scale model of cable-stayed bridge based on probabilistic residual fusion.Taking advantage of the mode shape with higher spatial resolution obtained by the mobile platform,the structural deterioration index based on the vibration mode and its variation is proposed.Considering that the test error and noise are random but the change of system parameters caused by local deterioration is deterministic,the index of different types and different orders are fused,as a result,the clarity of indicator on the location of deterioration was improved significantly.The index is applied to single blind test and multiple survey of bridge deck,and the sensitive deterioration detection and location are realized for different deterioration conditions.