Application Of Beam End Rotation Response In Bridge Detection And Evaluation

There are a large number of Bridges in China,and with the increase of service time,they will eventually enter the aging maintenance period.Damage detection and bearing capacity evaluation of bridge structures have always been the focus of bridge engineering research.It is widely adopted to detect and evaluate the load effects such as strain,deflection and rotation of bridge structures under deterministic load.Beam end rotation of the bridge is relative to the strain and acceleration,which can better reflect the overall deformation effect of the structure.Compared with the deflection,it has the advantage of testing convenience and is an ideal index for bridge testing and evaluation.In this paper,the application of bridge detection and evaluation is studied based on beam end rotation parameters.The main research contents and conclusions are as follows:1.The correlation between deflection response and angular response is established according to bridge geometric parameters and load location information,and intermediate variables are identified in combination with the measured angular response to realize reconstruction of bridge deflection response from rotation measurement point data.The results show that the deflection response reconstructed based on rotation data is highly consistent with the actual deflection response.On the other hand,this method combines load information and bridge geometry parameters,and can reconstruct the deflection response based on a single rotation response,which has good practicality and can provide a new data source or way for bridge detection and evaluation based on deflection.2.The influence line of the actual beam end rotation is extracted from the beam end rotation response under moving load,and based on this,the local damage identification of the bridge is studied.For statically indeterminate structures,the basis function fitting method is used to construct the undamaged basis function and the damaged basis function,so as to realize the structural damage identification without reference information.For statically redundant structures,structural geometric parameters and influence line of bridge beam rotation in undamaged state are introduced to identify the bending stiffness constant of bridge structure,and the structural damage identification under datum information state is realized.3.Construct the amplitude and area check coefficients of the actual angular influence line.The difference between the bearing capacity evaluation index and the static check coefficient is considered under the condition of the overall and local stiffness reduction of the bridge.The research shows that the constructed evaluation index can be used as a good parameter to replace the static check coefficient and realize the rapid evaluation of bridge bearing capacity under moving load,which has the advantages of convenience and economy.