Study On Identification Of Vibration Voiceprint Characteristics Of Long-span Continuous Rigid Frame Bridges Under Vehicle Excitation

Usually, crack damages of long-span continuous rigid frame bridges occur morefrquently and earlier than expected, seriously affecting structure performance anddurability. The subject of this paper is long-span continuous rigid frame bridge, thepaper studies structure damage identification method based on random vehiclestimulation. On the basis of the previous studies, this paper puts forward a systembased on theories of dynamics, wave mechanics and informatics. This system wasestablished by using vibratory mode and voiceprint identification.The main research contents are as follows:The field-tested acceleration data of Yunnan Heichonggou Bridge are analyzedfor the low order natural vibration frequency; and a finite element model of YunnanHeichonggou Bridge is established for calculation of the natural frequency. The resultsof above analysis deny the feasibility and practicality of structural damage detectionmethod based on low order natural frequency change. Moreover, the influence ofprestress change on the dynamic characteristics of the structure is studied to verify ifthe prestress loss could be really identified in the dynamic way.In accordance with the theory of similarity, a scaled-down physical model ofHeichonggou Bridge is designed. And an experimental program was schemed. In theexperiment, the acceleration data under hammer mode and vehicle stimulation modeare measured. Then, a finite element model is established for calculation of thephysical model natural frequency.Modal analysis, spectrum analysis and voiceprint analysis are carried out on thescaled-down model, to study the probabilistic stability of the high frequencies whichreflect the physical characteristics of local structure geometry and physics; in the endthe application of the higher order frequency under vehicle stimulation to long-spancontinuous rigid frame bridge damage identification is explored in this paper.