The Finite Element Model Updating Of The Xiangyang Hanjiang Bridge Five Based On Completed Bridge Load Test

Xiangyang Hanjiang Bridge Five is a typical long-span continuous rigid frame bridge, the structure of the arch rib and box beam combining parts is complex. As the controlling project of Xiangyang inner ring, it is of great value to use the load test results to make an updating of the finite element model in the long-term health monitoring. This paper systematically introduces the influences of several key factors in establishing the whole finite element model, and makes a local finite element analysis on the complex parts of the arch foot. On this basis, using the load test results and the artificial neural network method a correction of the initial finite element model is made. Then we mainly analyze and discuss the reasonable rigid zone and structural physical parameters at the stewback of arch bridge. The influence of Young’s modulus on the deflection in static loading test is analyzed. Using the research results above in the fluctuation test combined with the boundary condition factors, the datum of static load test of the artificial neural network are reasonably corrected, finally a more reasonable and reliable finite element model has been got. The following is the specific work carried out in this article:(1) In the first half of the thesis, the reasonable finished state of the whole finite element model of Xiangyang Hanjiang Bridge Five is studied, the impact of the usage of beam elements or plate elements in stewback, pile-soil effect, cable force optimization are discussed, and local stress of ANSYS finite element model is analyzed in detail. By comparing the differences between the calculating results of ANSYS and MIDAS software, some modifiable factors are discussed. The work sets up a good foundation for the later model correction.(2)The analysis and study on arch foot region’s joint stiffness of Xiangyang Hanjiang Bridge Five show that an influence of nodal rigid zone exists at the confluence of beam and arch in continuous rigid frame arch bridges. If it has not been included in the data correction consideration of static and dynamic load test, the structure’s load effect coefficient will produce a large error. Because of the regulations in the existing ‘Building Codes’ for rigid zone is not clear, to determine the appropriate length of rigid region in continuous rigid frame arch bridges needs specific analysis. This paper uses artificial neural network’s powerful adaptive learning ability to train a better domain size under the condition of setting up a group of different rigid domain sizes. Under the domain size the calculating results of the corrected finite element model fit the measured datum of the static loading test.(3) After considering the effect of rigid zone the effect coefficient of most sensors increase to 0.7~0.8. The result has not been highly consistent with the structure of the actual engineering. As an important physical parameter of the structure, the young’s modulus of real value and specification design has certain deviation. Due to the construction, material aging, external environment factors, Young’s modulus of concrete, arch rib and pre-stressed tendon all have to be modified. Based on the sensitivity, the elastic modulus of concrete, steel arch rib and pre-stressed tendon have been taken into consideration as adjustable parameters of model’s modification with rigid domain size. We take the Young’s modulus as the main consideration factor of model’s modification and rigid domain size as deputy factor. They are combined again using the method of uniform design. Using the artificial neural network the datum have been trained. Finally a group of optimal portfolios have been selected. Based on the group of optimal portfolios, the deflection of the finite element model of Xiangyang Hanjiang River Five is closer to the measured values. The calculated results of the first five order’s natural frequency are in good agreement with the measured values of the bridge’s pulsation test, and vibration modes can correspond completely. It indicates that we have got the finite element model which is most consistent with the actual structure of Xiangyang Hanjiang River Five. It can be used as the baseline finite element model of long-term health monitoring system in the bridge’s operation period.