Research On Hinge Joint Damage Identification Method Based On Vehicle Load And Power Spectrum Sensitivity Analysis

With the rapid development of bridge engineering and transportation industry in China,bridge diseases are becoming more and more serious.Prestressed concrete hollow slab bridge is one of the most commonly used and developed structural forms in the bridge construction technology.Hinge joint is the key to the overall collaborative performance of this kind of structure and the most vulnerable part during service.After several years of bridge operation,the hinge joints will have different degrees of water inflow,cracking and even concrete spalling,resulting in the weakening of the transverse connection between the deck plates,the longitudinal cracking of the deck,and even the stress of the single plate.In order to qualitatively and quantitatively evaluate the hinge joint damage of bridges with different degrees,a hinge joint damage identification method based on vehicle load and power spectrum sensitivity is proposed.The specific research contents and conclusions are as follows:(1)The distribution of random vehicle load is fitted according to vehicle type,and the mixed random vehicle load response spectrum is simulated according to the distribution.(2)The sensitivity matrix of response power spectrum with the position and length of hinge joints as damage parameters is derived;The simulated random vehicle load response spectrum is applied to the hollow slab bridge to obtain its response power spectrum.Combined with the sensitivity method,the location and degree of hinge joint damage are taken as the variables to be identified.The response of a few measuring points under a specific frequency value is selected to construct the statically indeterminate equations about the variables to be identified.The damping least square method is used to solve the equations to obtain the location and degree of hinge joint damage.(3)The numerical simulation of the hollow slab bridge composed of five slabs verifies the feasibility,accuracy and noise resistance of this method.The results show that the appropriate frequency range and response measurement points are selected according to the structural characteristics of the hollow slab bridge,and the method based on the power spectrum sensitivity analysis under the action of random vehicle load spectrum can not only accurately identify the position and degree of the hinge joint of the hollow slab bridge model under different damage conditions,but also realize the synchronous identification of multiple hinge joint damage,and the number of iterations is less and the calculation efficiency is high.Adding different levels of noise to the structure,the proposed method can still accurately identify the location and degree of hinge joint damage.(4)The finite element simulation,modal experiment and long-term health monitoring of Huanghuagou Bridge are carried out,and it is found that the first two natural frequencies of the bridge structure have little difference,and the confidence of the results is verified by the modal confidence criterion(MAC).By analyzing the response power spectrum of the existing monitoring data,it is found that the ambient temperature has a certain impact on the response power spectrum,which provides a certain basis for the next step to study the damage identification of hinge joints excluding temperature.